Oct. 22, 1946. |_. v. LEWIS 2,409,696 7 REMOTE CONTROL SYSTEM m Filed March 6, 1943 5 Sheets-Sheet l Oct; 22; 1946. 2,409,696‘ L. V. LEWIS REMOTE CONTROL SYSTEM Filed March 6, 1943 s Sheets-Sheet 2 INVENTOR & HI!’ ATTORNEY Oct. 22,1946. L. v. LEWIS ‘ 2,409,696 ‘REMOTE CONTROL SYS'ITEM Filed March a, 194:5 5 ‘Sheets-Sheet. 3 @L ’ INVENTOR‘ [1090’ 1/. [ewz'r Oct. 22, 1946. v|_. v. LEWIS 2,409,696 ’ REMOTE CONTROL SYSTEM Filed ‘March 6/1945 5 Sheets-Sheet 5 w . mymm§§ MWMIR‘MRN QH RmMd§§@MrQ.E“,Ra RM“. Hgmv uwh. “L E.m M .. R Rm W@ m.“$3M, | Patented Oct. 22, 1946 2,409,696 VUNITED STATES PATENT OFFIC 2,409,696 ‘ ‘ REMOTE CONTROL SYSTEM Lloyd V. Lewis, Pittsburgh, Pa., assignorto The Union Switch & Signal Company, Swissvale, Pa., a corporation of Pennsylvania Application March 6, 1943, Serial No. 478,252 1 12 Claims.‘ (Cl. 177-353) My invention relates to remote control systems, and more particularly to centralized tra?‘ic ‘con trol systems for railroads in which a central o?ice is connected with a plurality of ?eld stations by line wires over which code signals are trans~ mitted at times for controlling selected devices at the stations, and at other times for indicating the condition of station devices at the o?ice. My invention is an improvement upon that dis closed in my Letters Patent of the United States 10 No, 2,229,249, granted January 21, 1941, for Be mote control systems. One object of my invention is the provision ‘ of a remote control system which is particularly adapted to the use of existing line Wires without interfering with their joint use for telephone or telegraph communication or for other purposes. To this end the system of my invention employs code signals of the alternating current type in which each code comprises a series of impulses of current of alternately opposite polarity and the time spacing of successive impulses deter mines the code character. One advantage of this type of code is that the line signals may be generated inductively and consequently no line 25 battery is needed. 2 the long steps of the code are registered and for a system capacity of 35 stations seven steps of the code are used. In the system herein disclosed, boththe short and long code elements are regis tered positively and the number of available combinations is greatly increased, six steps for example, being su?icient for the selection of 64 stations. In respect to this feature, my inven tion is an improvement upon that shown in Let ters Patent of the United States to Snavely et al. No. 2,183,155, issued December 12, 1939, for Re mote control systems. Another feature of my invention relates to a‘ reduction in the number of relays required for selecting purposes. The selection of the stations _ is effected by the operation of a group of pilot re lays, and generally requires but one such relay for each selecting step of the code. The opera tion ‘of the pilot relays is so checked as to permit I their utilization in both the picked up and released positions. Another feature of my invention comprises the provision of a pair of relays of the stick polar type arranged to remain in their last operated position when denergized, for registering the short or long character of the code elements. Another advantage is that signals of this type . These relays are operated alternately by the code will pass readily through transformers or repeat elements as received and serve to store their char ing coils, permitting line circuits to be used which acter for delivery to the proper storage relay are not available for battery systems. My system, 30 while the next element in turn is being received. however, does not require the insertion of any Another object of my invention resides in pro apparatus in series with the line, nor is a me visions for allowing only one code to be stored at tallic connection to the line Wires essential. Fur the control oflice at a time, thereby insuring that thermore, the apparatus at the oince and at the a series of codes set up manually in a given order several stations is connected to the line wires in 35 will be transmitted in the same order rather than parallel and the operation of the system is inde in an arbitrary order of code superiority. This pendent of the relative location of the. office and arrangement is of advantage, for example, in the several stations, one advantage of which is the operation of a series of track switches to set that in the event of an interruption due to a up a route and in eifecting the clearing of a sig break in the line service may be quickly restored 40 nal governing traffic movements over the route as by main o?ice switching, for example, by con soon as it is fully set up and eliminates the need for a route circuit network for governing the order of transmission of the codes as required A feature of my invention comprises the pro heretofore. In accordance with this feature of vision of interference preventing means which 45 my invention the character of the code to be necting the line in parallel with a spare line at its opposite ends. . serves when two or more codes are initiated at the same time to effect their transmission sequen tially in a given order, and also to stop the trans- I mission of a code which is interfered with by im pulses of foreign current. The interrupted code. may then be reinitiated manually or automati cally for retransmission in its entirety. 7 Another feature of my invention relates to the more e?icient utilization of the code elements. In the system of the prior patent mentioned, only. transmitted is determined by the momentary operation of a selected starting button without the use of individual code ‘determining or start ing relays vas generally used heretofore. The ap paratus is also arranged that the latter may. be used to store a plurality of codes for transmission in a ?xed order without interference when desired. The system of my invention employs a chain of counting relays similar in number‘ and ar rangement to those Of my prior patent, but in 2,409,696 3 eludes novel arrangements for governing the op eration of these relays to render them responsive only to a particular code, no other selecting re lays being needed except when it is desired to have them respond to more than one code. Another feature of my invention resides in the 4 In the accompanying drawingsi _ Figs. 1A and 1B taken together, show in con densed form the apparatus at the control of?ce' in a typical centralized traffic control system em bodying my invention, Fig. 1A showing the office coding unit and Fig. 1B the associated o?ice storage apparatus. connection of the stick polar relays for register Figs. 2A and 2B, taken together, show the cor ing code character, in series with the counting responding apparatus at a typical ?eld location, relays, whereby each counting relay together with Fig. 2A showing a coding unit which is struc the polar relay energized in series therewith func 10 turally similar to that at the o?ice but which has tions like a polar-neutral relay in providing checks different terminal connections, and Fig. 2B the against improper operation. That is to say, those storage apparatus at a station having only one circuits which include polar contacts also include unit group of devices to be controlled, each such neutral front contacts the closing of which checks being identi?ed as a station. the energization of the polar relay in the normal 15 group Fig. 2C illustrates a modi?cation which is to be or reverse direction and thereby indicates that substituted for Fig. 23 at each ?eld location its contacts are in a proper position. ' where the number of devices to be controlled ex Another feature of my invention resides in im ceeds the capacity of a single station or panel. proved arrangements for controlling a transmit Fig. 3 shows a modification of the office select ter relay for generating the code, in which each 20 ing circuits which may be substituted for a por ‘operation of the relay depends upon the closing tion of Fig. 113, to provide for the storage of con of a different one of a series of successively pre trol codes for transmission in a given order, as hereinbefore referred to. Another feature of my invention relates to the Fig. 4 shows a pair of relays which may be sub provision of improved means for preventing un 25 stituted for any one of the pilot relays P of the due delay in the transmission of codes from the other views to obtain the requisite contact ca pared circuits. different stations under conditions of heavy traf ?c, due to the fact that the stations normally pacity when this exceeds the capacity of a single relay. Similar reference characters refer to similar 30 superiority. parts in each of the several views. IA leading object of my invention is the pro Referring to Fig. 1A, the reference characters ' vision of a system of the desired scope in a form Y and Z designate a pair of line wires which pro which can be readily maintained to minimize vide a line circuit for the centralized tra?ic con service interruptions and which is readily adapt trol system of my invention. It is to be under able to widely different conditions. On the one 35 stood that these wires extend continuously the hand, maintenance is facilitated by mounting the length of the territory controlled by the central relays in one or more unit housings with detach ized traffic control system, and that they may be able connections, while on the other hand, dif used jointly for telephone and telegraph com ferent conditions require a variety of units some munication like the similarly designated line 40 of which may contain idle relays and may be more wires shown in Letters Patent of the United efficiently provided for by the use of separately States to Baughman et al., No. 2,803,875, issued mounted relays wired individually according to December 1, 1942, for Remote control systems. their location. To meet these diverse require The system of my invention utilizes the line wires ments those relays which are invariable, that is to provide a channel for the transmission of low to say, those the functioning of which is required frequency alternating current of the order of regardless of their location or of the scope of the six cycles per second, and communication be installation are mounted in a detachable coding tween the o?ice and stations is effected by means of codes each comprising a series of alternations unit such as is provided in the system of my prior patent, having detachable connections to which 50 or impulses of alternately opposite polarity hav ing a low frequency of the order mentioned, with those storage relays may be connected which vary pauses interposed to provide code character. according to the location. One improvement re The C. T. 0. line channel in its normal idle con sides in the arrangement of the coding unit so dition comprises the line wires Y and Z in series, that it may be used at the office or at any station, only one spare unit being required for each instale 55 with a connection bridged across the line wires through the coils l2 of a low pass ?lter and the lation, while other improvements comprise ar high resistance winding of a line relay R at the rangements whereby the number of variable re office, as shown in Fig. 1A, and also at each sta lays has been decreased. tion, as shown in Fig. 2A, the transmitting appa A further feature of my invention resides in the arrangement of the coding unit or that cer 60 ratus at the office and wat each station being normally disconnected from the line. Each line tain of the steps of the code may be used to pro relay R is of the stick polar type, like relay OR vide additional controls and indications in instal of the above-mentioned Baughman et al. patent, lations in which they are not required for station and is arranged to hold its contacts magnetically selection. Certain features of the system of my invention 65 in their last-operated position when the line is idle and also during the pauses between successive disclosed but not claimed herein, are claimed in impulses of a code, the contacts of each line relay my divisional applications, Serial No. 549,276, have access to the line in a ?xed order of code . ?led August 12, 1944, for Transmitting apparatus I ‘R normally occupying their left-hand position, for remote control systems, and Serial No. 549, 277, ?led August 12, 1944, for Selecting apparatus 70 > for remote control systems. I shall describe one form of apparatus embody ing my invention and various modi?cations there ~ of, and shall then point out its novel features in '; claims. as shown. Each coding unit, such as the one shown in Fig. 1A, includes transmitting apparatus gov erned by its line relay R, consisting of a starting relay ST, a master relay M, a transmitter relay ‘ T and an impulse transformer I3, this apparatus 75 functioning as follows: Relay M is picked up, 5 2,409,098 ‘and is held energized to condition the'coding unit for transmission, by momentarily energizing relay ST. The closing of front contact a‘of relay M then completes a circuit from the supply ter minal B of a suitable local source of current over ‘of relay L2 over back contacts 0 and b of relays Li and LB and the local winding of relay R to terminal C. Relay R will thereby be restored to normal, reenergizing relays Ll, LP and LB, and ‘then the timing relays will release in the order back contact 01 of relay T and through the lower L2, LP, LB and LI. Each code consists of sixteen primary coil of transformer I3 to the common impulses and hence relay R. is operated to nor return terminal C of the local source. At the mal by the ?nal impulse and the timing relays same time, the closing of front contact 01 of relay release in the order last mentioned at the end M connects the secondary winding of transformer 10v of each code. A code may be initiated only when i3 across the line wires Y and Z through the coils relays LI and L2 are both released, and it follows l2 and [2a of a low-pass ?lter and the closing of that successive codes are spaced by an interval front contact 0 of relay M completes the first of a which is materially longer than any interval be series of circuits governed by the associated line tween successive impulses of a code. relay R‘ in a manner hereinafter described, by 15 Each line relay R also controls a chain of means of which relay T is operated periodically at counting relays l to 8 and [6 for counting the intervals spaced in accordance with the desired code impulses, and in series therewith controls code. Each time relay‘T picks up, the operation a pair of stick polar relays KSI and KS2 which of its contact d reverses the direction of the cur are operated to normal or reverse to register rent through transformer [3. The periodic oper 20 code character in accordance with the time ation of relay ‘T thus causes transformer It to spacing of the impulses. When relay R reverses deliver induced impulses of alternately opposite in response to the ?rst impulse of a code, the polarity to the line circuit, the time spacing of energization of relay LI as above described com ‘which characterizes the code. Each code nor pletes a circuit from terminal B at the right mally comprises sixteen impulses, providing ?f hand contact 22 of relay R over front contact b teen code elements of selectable character. of relay Ll through the upper winding of relay ' Each line relay R, controls a group of slow re KSI, back contact a of relay LB, front contact 9 lease timing relays Ll, L2, LP and LB, corres of relay Ll through relay l to terminal C. Relay l therefore picks up and relay KSI is held nor ponding to the similarly designated relays of my prior patent. The timing of these relays is gov 30 erned by means of electronic recti?ers as shown, in the manner explained in the patent, the recti ?ers also serving to prevent contact sparking and to minimize contact wear. mal, as shown. Relay LB then picks up and shifts the circuit for relays KS! and I to the branch path extending from the right-hand ter deenergizecl, and during the remainder of the 50 impulse. minal of relay KSI over front contact a of relay LB, back contact I) of relay 2 and thence over the In response to the ?rst impulse of a code, each . front contact a and winding of relay I to ter line relay R reverses, and its right hand contact minal C. a completes a circuit from terminal B over back If the ?rst element of the code is short, relay contact a of relay L2, back contact 0 of relay LB, KSi‘ is left deenergized with its contacts normal through relay Ll to terminal C. Relay Ll then as shown, when relay R is operated to the left by picks up and its contact a completes a circuit for 40 the second impulse, but if the ?rst element is long, relay L2, whereupon relay L2 picks up and com relay Ll releases before the second impulse is pletes circuits over front contacts 0 of relays L2 received and the closing of its back contact 0' and L! to Dick up relays LP and LB, which relays, shifts the circuit for relay l to include the lower as will be apparent from the drawings, are ar winding of relay KSI in place of its upper wind ranged to pick up simultaneously and to release ~15 ing thereby reversing the direction of energize successively following the release of relay Li or tion of relay KS! to cause the contacts of relay L2. When relay L2 picks up, its contacts a and KS6 to move to the right. In this case relay d shift the circuit for relay Ll to the left-hand KSi is’ left deenergized with its contacts re contact a of relay B. so that relay Ll becomes versed when relay R is operated by the second code relay Ll is energized by relay R over front contact 0 of relay LB when relay R is in its normal position, while relay L2 is'energized over its own front contact a when relay R is reversed. q ' In response vto the second impulse of a code, relay R closes a circuit fromjerminal B at its left-hand contact 22 over front contacts 6 of relay LB and b of relay L2 through relay KS2, ,RelaysLi and L2 remain pickedv up during the 55 back contact a of relay 8, front contact b of relay brief intervals between ‘successive impulses con I through relay 2 to terminal C, whereby relay 2 stituting the short elements of the code, and one is picked up and relay KS2 energized in the nor or the other of these relays releases during each mal direction as shown. If relay L2 releases be pause constituting a long element and they thus fore the third impulse is received, relay KS2 will serve to indicate code character. Relay LP is 60 be reversed thereby, that is, relay KS2 is left de deenergized upon the release of relay Ll or L2 and governs the length of the‘ long code elements ‘transmitted by the associated transmitter relay energized in its normal or reverse position de pending on whether the second element is short or long, while the third element is being received. T. Relay LB is a bridging relay which remains Relays 3 to 8 are provided with circuits gen picked up for the duration of a code and controls 65 erally similar to those for relays l and 2 various local circuits as hereinafter pointed out. and are arranged to pick up one at a time in Since relay R is normally deenergized, it may the same Way in response to the corresponding happen that it will be reversed accidentally when impulses of the code, each in series with relay the system is in its normal at ‘rest condition as, ‘ KS! or KS2‘ as described. for» example, by an impulse of foreign current. 70 When relay 8 picks up, a chain repeat relay ‘If this occurs, relays Ll, L2, LP and LB will pick CR is energized over a circuit extending from up as described and then relays Ll, LP and LB terminal B at the front contact f of relay LB will release in that order, relay L2 remaining ' over contact 0 of relay‘ 8 and the winding of relay picked up to close a local restoring circuit for relay ‘R. extending from terminal B at front contact or CR to, terminalC, and relay CR, picks up com pleting a stick circuit at its contact a whereby 2,409,696 7 relay CR is held energized until the end of the code. Contact I) of relay CR prepares a circuit for energizing relay l next inv order after relay 8, and relays l to ‘i operate through a second cycle in response to impulses 9 and 15 of the code. Contact e of relay CR serves to cause relay [6 to be operated in place of relay 8 in re sponse to the sixteenth or ?nal impulse. It will be understood that on each step except the last, relay KS! or KS2 is positioned to normal or reverse in accordance with the short or long character of the corresponding code element and is held deenergized in its last operated position to store the code character for the duration of the next succeeding code element. As explained 15 in more detail hereinafter, contacts b of relays KS are included in circuit portions leading over Wires 56—59 to coding unit terminals which may be adiustably connected externally to those terminals which lead over wires 22-21 to the right-hand terminals of the counting relay winde ings. These circuit portions provide selectively controlled connections to the common terminal C of the locaLsource which serve during the ?rst 8 lamps, of which only the one for station No. 1 is shown, this including a starting button IPB for initiating the transmission of a control code con taining the code call for station No. 1, a switch lever SW and a signal lever SIG for controlling the switch and signal relays at station No. 1, the levers being operatively associated with the coding unit by the energization of a selector relay OIS. The indication lamps of the panel are con trolled by a group of indication relays K, which are operatively associated with the coding unit by the energization of a delivery relay OID, energized in response to an indication code re ceived from station No. 1. Each code call comprises a distinctive combi nation of long and/ or short steps, four steps pro viding sixteen such code calls. The o?ice coding unit is arranged to transmit control codes of sixteen steps or code elements, in which the ?rst and second are short; steps three to six, com prising the code call, either short or long; and steps seven to ?fteen either short or long, to selectively control nine devices at the selected station, step sixteen governing the return of the apparatus to normal at the end of the code. In the speci?c arrangement chosen for illustration the code call for station No. 1 comprises four long steps; the seventh step is used to control a maintainer’s call signal lamp MC, at the selected station, by closing a key M03, and steps eight, nine and eleven are used to control the relays WS, LI-IS and RHS in accordance with the positions of the control levers SW and SIG. The remaining steps, not needed for control pur cycle of operation of the counting relays to pre vent their continued response to a code to which the apparatus is not adjusted to respond and to check the positions of the pilot relays P of Fig. 1B. During the second cycle of operation of the counting relays, the closing of contacts 0 and d of relay CR connects wire 56 to wire 58, and wire 5'1 to wire 59, and thus renders the operation of the counting relays independent of the position of contacts b of KSI and KS2, and during this cycle the pole changer contacts a and c of the 35 poses, are made short steps. Each code call is set up for transmission by relays KS control the polarity of the current sup positioning a group of four pilot relays, P3 to plied to a series of circuits prepared by the clos P5, Fig. 1B, in a distinctive pattern, the contact ing of front contacts 1‘ and g of relay CR, com d of each of these relays controlling relay T to pleted externally by suitable connections to the coding unit terminals over wires 46-55, which 40 generate a long step of corresponding number if the relay P is picked up and to generate a short as shown in Fig. 1B control the indication relays step if such relay remains released. K. Relay KSI also controls relay E in accordance The step by step transmission of a control code with the character of the ?rst element of the to station No. 1, in response to the operation of code, which is made a short element in each con trol code transmitted from the office and a long 45 the starting button IPB will now be described, assuming the control levers to occupy their velement in each indication code transmitted from normal positions as shown. a ?eld station. The energization of relay E con The transmission of a code by any coding ditions the coding unit to function as a receiver. unit may be initiated only when the coding unit The application of the apparatus of my in vention to a speci?c installation will now be ex 50 is in its normal at rest condition, so that relays plained, assuming for sake of illustration that it is employed in a centralized traffic control LI and L2 are both deenergized. In that case terminal B at back contact 0 of relay L2 is con nected over back contact d of relay Ll to wire l1, and a code may then .be initiated by connecting track plan in Fig. 2B. This group comprises a,“ 55 wires ii and I5 together to complete a circuit to pick up the starting relay ST. Assuming that track switch IW and a group of signals LH and button IPB is operated, under the condition de which as indicated diagrammatically on the scribed, the connection from terminal B at wire drawings are arranged to be controlled by code ll will be extended over contacts I) to e of button by the operation of a group of polar stick relays including a switch control relay WS and the 60 lPB to wires 13 to 16 and thence through the upper windings of each of the relays P3 to P6 signal control relays LHS and RHS. It is to be to terminal C. Relays P3 to P6 pick up, as re assumed that the installation includes not more quired for the code call of four long steps identi than sixteen such locations, each having a coding fying station No. 1, and extend the connection unit arranged as in Fig. 2A and connected by from terminal B at wire I1 over their contacts line wires Y and Z with one at the control o?lce, 0 to wire [5 and thence through relay ST to arranged as in Fig. 1A. At the location of switch terminal C. Relay ST picks up, and completes a IW, the coding unit connections are arranged circuit from terminal B over its front contact c, precisely in Fig. 2B, this location being identi shown at the right in Fig. 1A, over back contact ?ed as “station No. 1,” the connections at the other stations being differently arranged so that 70 1‘ of relay M to wire 2| and thence over con tacts e of relays P3 to P6 in series, through relay each is responsive to a distinctive code call. OlS to terminal C. Relay OIS picks up, and At the office, the coding unit connections are the closing of its front contact 7‘ connects ter arranged as shown in Fig. 1B, and include a con minal B at contact I of button IPB to wire 28 to trol panel for each station containing the usual . complement of control levers and indicationg 75, complete a circuit over front contact a of relay system for contr‘olling spaced groups of traf?c governing devices such as the one shown in the 9 2,409,696 ST, back contacts g and h of relays LB and E through relay M to terminal C. The energiza wire 6! a short odd-numbered code element will be generated for the reason that relay T will be tion of relay M over the circuit just traced ener shunted as soon as the corresponding counting gizes the impulse transformer l3 and connects it to the line as already explained. relay' picks up. If the connection is made to wire ll, a long element will be generated, relay T being held energized after the counting relay has picked up until relays Li and LP release and the connection is completed by the closing of It is to be un derstood that when transformer I3 is energized over the branch including back contactd of relay T the resultant line impulse is of normal polarity to operate each line relay R to the left, and when “rack contact b of relay LP. _ it is energized over front contact (1 of relay T 10 The even-numbered code elements are similarly the resultant impulse is of reverse polarity to controlled by external connections to ‘wires Ell operate each line relay R to the right.' The and ‘Ill. The second element, for example, will initial impulse due to the closing of contact a be a short element when wire 32 is connected to of relay M therefore tends to operate the relays wire 60 because‘ a circuit will be closed to pick up R to the position they already occupy and is not relay T, at back contact (1 of relay l as soon part of the code, its purpose being to insure the as relay l is released following the energization proper initial magnetization of transformer l3. of relay 2. If on the other hand wire 32 is con When relay OI S picks up, the opening of its nected to wire 70, a long element will be gener back contact is extinguishes any of the indication ated, relay T remaining deenergized until relays lamps of the panel, such as lamp NH, which may 20 L2 and LP release toclose the pickup circuit at be lighted, thereby indicating to the operator back contact c ofrelay LP. that the code has been initiated. When relay It follows therefore that after relay T is initi M picks up, it completes a stick circuit for the ally picked up by the operation of relay ST it pilot relays P extending from terminal B at front continues to operate periodically to generate a contact 6 of relay M to wire I 9, and through the 25 code, provided relay M remains picked up and the lower winding and front contacta of each of the associated counting relays respond. Each time relays P3 to P6, to wire I 8, and thence to ter relay T picks up it is held energized over its minal C at back contact 0 of relay E. The clos stick circuit until the associated line relay R re ing of front contact I of relay M connects ter- ' verses to pick up an odd-numbered counting re minal B directly to wire 2!, to hold relay OIS 30 lay, contact d or e of which connects terminal picked up, and the operated starting button IPB B over wire 6|, or‘ ‘H to the left-hand terminal of may now be released. relay T to release it by short circuiting its wind As soon as relay M picks up, relay T becomes ing. Each time relay T releases, relay R is ‘oper energized over the circuit extending from ter ated to normal to pick up an even~numbered minal B at contact 0 of relay M, contact b‘ of 35 counting relay, whereupon the last operated odd relay ST, through the winding of relay T and numbered relay releases to prepare a pick-up resistor 29 to terminal C, and relay T picks up to circuit for relay T closed over wire 60 or 10. deliver the ?rst impulse of the code to the line In the control code being described, the ?rst to reverse all line relays R in unison, each of step is short, due to the fact that relay T is which operates its timing relays and counting 40 shunted by the connection over front contact (1 relay l as already described. In the coding unit of relay I and wires 31 and BI, Fig. 113,‘ as soon as which is transmitting the code the energization relay I picks up, the code being thereby distin of relay LB transfers relay M to a holding circuit guished from an indication code transmitted from having one branch extending from terminal 13 a ?eld station which, has a long ?rst step. The over the normal contact 5 of relay R and‘ back 45 second step is made a?xed short step by a con contact I) of relay T, and another branch extend» nection over back contact (I of relay I- and ‘front ing from terminal 13 over the reverse contact I) contact (1 of relay 2, over Wires 32 and‘ 66, over of relay R and the front contact b of relay T; which relay T is picked up in response to the re thence over front contacts I) and g of relays M lease of relay I. The front contacts d of relays and LB, back contact 71. of relay E‘ and the winding 50 P3 to P5 are nowclosed, so that wires 33 to 35 of relay M to terminal C. Relay ST becomes are connected to wire lllor ‘H and‘ the closing of deenergized but is made sufficiently slow‘ release thecircuits including the front contacts a! of re by the provision of a recti?er unit‘as- shown so lays 3 to 6 is delayed until relay LP releases on that although its energizing circuit is; opened each of the steps three to six, thereby making when relay‘Ll picks up, it remains picked up 55 these steps long. Assuming key MCB to be open, long enough to permit relay LB; to pick up to relay P‘! will occupy its released position, and the complete the stick circuit for relay _M. When ‘seventh step will be made short due to the con relay T picks up it is held energized independently nection from wire 3'! over back contact (I of relay of relay ST over a stick circuit including its own front contact a. When relay I picks up, a con nection extends from terminal B at contact 0 of relay M over back contact I) of relay CR and front contact (1 of relay I to wire 3!. The wires 3! to 45, inclusive, provide external connections Pl’, to wire 6|. 60 The code transmission continues through the seven steps as described only if the code delivered to the line by which relays KSl‘and KS2’ are operated, is of the corresponding pattern. Un less the ?rst step is short, the o?ice relay E picks for completing a series of circuits, closed one at a 65 up as hereinafter described, and its back contact time by the counting relays, for controlling the periodic operation of relay T to determine the desired. character forv each. of the elements one to ?fteen, respectively, of the code. Any of these h opens the circuit for relay M to stop further transmission, Unless relay KS2 remains normal to register a short secondstep, relay 3 is not operated, its circuit extending from its right wires connected to terminal B over a contact 70 hand terminal over wires 22 and 56 to terminal (1 or e of an odd-numbered counting relay may cat the normal contact I) of relay KS2. Simi be connected externally to wires 6| or ‘H to extend larly, the operation of relay 4 is dependent upon the connection of terminal B to the‘. left-hand the reversal of relay KS! to register the long terminal of relay T so as to shunt the relay to third step, the circuit for relay 4 extending from cause it to release. If the connection is madeto 75 wire 23 over ‘front. contact b of relay P3 to wire aroma 59 and thence to terminal C over the reverse con tact b of relay KSI. Relays 5 to ‘I are controlled 12 operate until the sixteenth step is reached, in When relay CR picks up on the eighth step, its contact 22 transfers the control of relay T from unison with the of?ce relays, and when relay CR picks up on the eighth step, a branch of its cir cuit is closed from terminal B over front contact I) of relay E to wire 9, thence through relay MCR to terminal C, over the pole changer contacts e and ,f of relay P1, whereby relay MCR is ener gized in the normal direction if relay P1 is re leased, and in the reverse direction if relay P1 is picked up. It is to be understood that relay MCR is of a the d contacts of the counting relays to a series of eight similar circuits extending from contacts e of relays 8 and l to ‘I, respectively, to wires 38 to 45 extending over contacts b to z‘ of relay OlS, to light lamp MC when energized in the reverse direction, and assumes the released position when energized in the normal direction, remaining in over similar circuits including front contacts b of relays P4 to P6, while relay B is controlled over a circuit including back contact b of relay Pl. It follows therefore that the office relay 8, and relay CR controlled thereby, is operated only if steps one to seven of the control code are of the desired character. for controlling the character of steps eight to magnetic stick type and that it closes its contact its last operated position when deenergized. Assuming the- eighth step of the code being ?fteen in accordance with the positions of the received to be short, relay KS2 will occupy its levers of the selected panel in the same manner normal position and the polar stick relay WS 01' as the preceding steps are controlled by contacts d of the relays P, as above described. The cir 20 Fig. 2A will be energized momentarily in the nor mal direction at the beginning of the ninth step cuit for step eight, for example, extends from over a circuit extending from terminal B at the wire 38 over contact b of relay OIS and lever right-hand contact I) of relay R, contact (1 of SW to wire 60 or ‘I0, and is therefore made a short relay LB, normal contact a of relay KS2, contacts step if lever SW is normal and a long step if lever SW is reversed. The signal lever SIG controls 25 g of relays CR and E, contact f of relay I, wire 48, relay WS, wire 46 and thence to terminal C the character of steps nine and eleven, both of at the normal contact 0 of relay KS2. If lever which are made short when lever SIG is normal SW had been reversed to make the eighth step as shown. Step nine is made long and step eleven long, relay KS2 would be reversed, and relay short when lever SlG occupies its left-hand posi tion, and step nine is made short and step eleven 30 WS would be energized in the reverse direction on the ninth step. Relays LHS and RHS are long when lever SIG occupies its right-hand po similarly controlled in accordance with the char sition, as will be clear from the drawings. The acter of steps nine and eleven, respectively, as remaining steps, in the speci?c arrangement de reflected by the position of relay KSI, these re scribed, are made short steps by the provision of direct connections from contacts d and f to i 35 lays being operated to normal or reverse on steps ten and twelve, as will be clear from the drawings. of relay OIS to wires 60 and SI. Each station coding unit is adapted to be con The transmission of the code being described is terminated with the dropping of relay T to ditioned to transmit indication codes in response begin the sixteenth step, during which the ap to the energization of a code storing stick relay, paratus returns to its normal at rest condition. 40 such as the relay ICS of Fig. 2B. Relay H5 is the ?rst to release, then relays L2, When relay I CS is energized, it connects wire LP and LB release. Relay LB releases relays M, l1 over its front contact I) to wire IE, to which CR and LI, and relay M releases relays P3 to P6 the starting relay ST of Fig. 2A is connected, and OIS, and ?nally, relay Ll releases. ‘and this relay ST when energized completes a 45 ' Considering now the mannerin which the con connection from terminal B over wire 28 and its trol code just described is selectively received at front contact a to pick up relay M. The ener station No. 1, and referring to Fig. 2A, since a gization of relay ICS thus corresponds to the coding unit like that shown in this view is pro operation of the starting button IPB in the con vided at each ?eld location, each of which is ‘trol code already described, that is to say, it is similar to that of Fig. 1A except for its external 50 effective When the system is at rest, to pick up connections, it follows that the line relays R and relays ST and M to initiate the transmission of the timing relays at all stations operate in uni an indication code by relay T at station No. 1. son with the corresponding o?ice relays in re Relay ICS may be picked up in response to sponse to the control code, likewise relays I, 2 changes in the condition of any of the indicating 55 and 3. relays at station No. 1, as hereinafter described in Each station coding unit is conditioned to detail; but it is also picked up upon the delivery function as a receiver by the energization of its ‘of a control code to station No. 1 over the circuit relay E on the second step, as hereinafter de extending from terminal B at wire 9 through its scribed. At station No. l, relays 4 to ‘I pick up on the 60 upper winding to terminal C. The transmission of a control code to station corresponding steps because wires 23 to 2B of No. 1 will thus be followed by a transmission of Fig. 2B are connected to wire 58 or 59 and the an indication code from station No. 1, in which circuits for relays 4 to ‘l are similar to those estab the operation of the station transmitter relay T. lished for the corresponding of?ce relays when of the line relays R and of the timing and count 65 relays P3 to P6 are picked up, as already de scribed. It is to be understood that at each other sta tion one or more of the wires 23 to 26 is con nected to wire 56 or 51 instead of to wire 58 or ing relays controlled thereby are generally similar to those already described. The indication code comprises sixteen steps in which the ?rst is made a long step by connecting wire 3| to wire 1!, as 59, as illustrated in Fig. 2C, for example, and 70 shown in Fig. 2B, instead of to wire 6|. Wires 32 to 31, in Fig. 2B, provide connections similar to consequently at each such station the operation those provided for the office relay T in the con of the counting relays terminates before reach trol code described. Consequently steps two and ing the eighth step of the code containing the seven will be short and steps three to six long, code call for station No. 1. At station No. 1, however, the counting relays 75 the connections of wires 33 to 36 to wire ‘In or 2,409,696 13 14 ‘H providing for the transmission of the code call 2, LI and LP in‘ each coding ‘unit. Since the connection for shunting relay T at each ?eld station includes wires 3| and "II, it will remain of four long steps identifying station No. 1. ' It is to be understood that at each other station one or more of the wires 33 to 36 is connected open and the station relay T will remain picked ' to wire 60 or 6|, as illustrated in Fig. 2C, for Or up until the associated relay M is released to example, to effect the transmission of different disconnect transformer 13 at that station from code calls. the line, leaving the office transmitter in control When the coding unit of Fig. 2A is in the trans to continue the code. It has already been mentioned that the coding relay M is connected to wire 19, preparing a 10 unit at each ?eld location is arranged to receive circuit which may be completed at contact a of control codes as identi?ed by a short ?rst ele relay R7 through the upper winding of relay ment bysuitable connections for relay E. Thus P1 to terminal C, whereby relay P1 may be con in Fig. 2A, wire ll is‘connected to wire [4, and trolled to make the seventh step short or long, since relay KS! remains in its normal ‘position, in accordance with the position of an indicating the‘station relay E is energized in multiplewith relay RT. The circuit by which relay P1 is held relay 2 at the beginning of the second step over energized in the receiving condition is ineffective a circuit extending from terminal B at the left mitting condition, terminal 13 at contact’ e of when relay P1 is subject to control by relay R1. wire I 8 being connected to terminal 0, at‘ back contact c of relay E. Steps eight to ?fteen of each indication code may be used to indicate the condition of eight other station devices by suitable connections to wires 38 to 45. As shown, wires 38 to 42, con trolling the transmission of steps eight to twelve, hand contact b of relay R, front contact e of relay LB, normal contact a of relay KSI, wires 20 l4 and II, contact 0 of relay l and the upper are connected to contacts (2 of the indicating re lays NWP, LHR, RWP, RHR and TS, while wires 43. 44 and 45 are connected to wires 5!, 60 and SI, respectively, so as to make these steps short. Since all the connections. except the one for the ?rst step, are similar to those for the o?ice relay T already described, no further description of the detailed operations involved in transmitting an indication code is deemed necessary. Since the first‘ step is long, relay E at the . transmitting station is not operated. This is also true of relay E at each other ?eld station, and consequently none of these are conditioned to re ceive the code. Since each transmitter has access to the line when it is free, it may happen, that two or more are set into operation at the same time. If this occurs, interference is avoided by stopping the de livery of impulses to the line by any coding unit which is transmitting a code if its line relay Pt? ' is operated by a received impulse during a pause in the operation of the associated transmitter T. If relay R is thus operated ‘to a position out of step with the relay T it controls, the stick circuit for relay M is opened at contact b of relay R, releas- ‘ ing relay M to disconnect the transmitter from the line, the coding unit then being in condition to transmit its code in its entirety when the ‘line is again free. winding of relay E to terminal C. Relay E there~ fore picks up, and completes a stick circuit over its contact a and lower winding. extending to terminal B at contact f of relay LB. By referring again to Fig. 1A, it will be seen that the o?ice coding unit is conditioned to receive indication codes having a long ?rst element by connecting wire H to wire 47, in which case the pick-up circuit for the oi?ce relay E extends to terminal B over the reverse contact a of relay KS]. As already explained, relay KS1 occupies its reverse position during the second step only if the ?rst element of the code is long. Referring now to Fig. 1B, it is to be understood that the key MCB controls the character of the seventh step of a control code initiated by the operation of any one of the buttons IPB to lliPB, to operate a maintainer’s call signal at the se lected station, and the operationof this feature will now be described. Assuming that key M013 is closed, and that button lPB is operated, a con trol code will be initiated as already described. When relay M picks up, a circuit is closed from terminal B at its front contact 6. Fig. 1A, over wire [9 and the contact of key MCB. Fig. 13, wire ‘l1 and the upper winding of relay P1 to terminal 0. Relay P'l therefore picks up, and its contact (I shifts the connection of wire 31 from wire 6! to wire 1!, causing relay T to generate a long sev enth step during which relay Ll releases to re verse relay KSI, the control code being in other respects‘ similar to the one already described in detail. ‘ ‘ ‘ ' At station No. 1, the release of relay Ll on Since the line relays R are of the, stick polar‘ 55 the seventh step completes a circuit from termi type, relay R at a station WhiCh‘is transmitting nal B at contact 1‘ of relay LB, Fig. 2A, over back a long code element is temporarily deenergized contact a of relay CR, front contact e of relay E, and in condition to respond to an impulse re back contact e of relay LI, contact 0 of relay '1, ceived from the line as required for the operation‘ wire 51 through the lower winding of relay FL of this feature. 60 of Fig. 213, to terminal C, so that the station re It will be readily apparent, therefore, that the lay P1 picks up completing a stick circuit over its use of'the line is allotted to the different stations contact a and wire l8, extending to terminal B in accordance with the relative superiority of at front contact 0 of relay E. ' their code calls, a short element taking precedence At the oflice and at station No. 1, a circuit is over a long element in each instance. Control 65 prepared for relay 8 extending from wire 21 over codes transmitted from the o?ice are given pre front contact b of relay Pl.’ wire 59 and the re cedence over indication codes transmitted from verse contact b of relay KS! to terminal C, so the stations by the provision of a short ?rst ele that relays 8 and CR pick up on the eighth step ment in each control code and of long ?rst and at station N0. 1, terminal B is connected to element in each indication code, as already eX~‘ wire 9, energizing relay MGR in the reverse di plained. Thus when a control code and an indi cation code areinitiated at the same time, the line relays at the oflice and at each station will ‘be operated by the second impulse of the code rection over front contracts e and ,f of relay P1 to light lamp MC, as required. The remain ing operations are similar to those occurring on the corresponding steps of the control code al delivered by the of?ce relay T, energizing relays‘ 75 ready described. ‘ 2,409,696 15 In describing the step-by-step operation of the system, it has been assumed that the apparatus of Fig. 1B has been arranged for sixteen stations, using the elements three to six of the code in different combinations of long and short elements to provide the sixteen code calls. Step two of a circuit including wires 41 and H over which relay E, Fig. 1A, picks up. On the second step, the code is made a ?xed short element by con necting wire 32 to wire ‘Ell. A pilot relay P is provided for each of the steps three to seven, having a contact d for controlling the transmis the closing of front contact e of relay E prepares pick-up circuits for the relays P which may be traced from terminal B at contact 1‘ of relay LB, back contact a of relay CR, front contact e of relay E, back contact e of relay Ll or L2, con tacts c of relays 2 to 1 and the corresponding wires 62—61, through the lower windings of re lays P to terminal C. In the case of relays P2 to P6, the connection to terminal C includes wire [9 and back contact e of relay M. Since the third step is long in the code being described, relay P3 will pick up over wire 63 and front contact 0 of relay 3 in response to the clos ing of back contact 6 of relay Ll on that step, and relays P4, P5 and P6 will pick up over corre sponding circuits on steps four, ?ve and six. Since the seventh step is short, relay P1 remains sion; that is to say, each of these steps is made long or short according to the position of the associated relay P. Relays P2 to P6 maybe arranged in sixteen different ways to complete a circuit from wire 2| over their contacts e to i to select any one of sixteen S relays, as indicated by the references OIS to OIBS, in Fig. 1B. - By the addition of a pilot relay P2 to the group of relays P3 to P6, to control the character of the second step, the number of stations which the system is adapted to control is doubled, five steps providing code calls for thirty-two stations. Relay Pl, as shown, provides an additional con trol or indication element in each code, but this released. A stick circuit is completed by each relay P relay may be used for station selection by arrang ing its circuits like those for relays P3 to P6, and it follows that the system may employ codes hav ing either ?ve selecting steps and nine function control steps, or six selecting steps and eight function control steps, the latter arrangement providing for the control of sixty-four stations. For the control of sixteen stations, as shown, the circuits controlled by contacts 6 to z' of the relays P consist of two sets of circuits for eight S relays each, selected over front and back con tacts e of relay P3. Similarly, to control thirty 16 received impulses and controls the associated tim ing relays, and that relays l and 2 respond as in the codes already described. Since the ?rst step is long, relay KSI is operated to reverse in series with relay l and its right-hand contact a prepares which picks up in response to the closing of back contact e of relay Ll or L2, which includes its own front contact a and extends over wire l8 to terminal B at front contact 0 of relay E. A check to insure against the failure of the relays P to assume the positions required for the code call being received is provided by the con nections for the counting relays 3 to 8 which ex 35 tend to terminal C over wires 22-21 and con tacts b of the relays P, wires 56-—59 and contact b of relay KSI or KS2. In response to each long element, relay KSI or KS2 is reversed and com pletes a connection to terminal C over wire 58 to wire 2| over front and back contacts, respec tively, of a relay P2, may be used. To obtain the 40 or 59 and front contact I) of that one of the re lays P which is picked up by the same long ele requisite number of contacts one or more addi ment, to prepare ‘a circuit for the counting relay tional relays may be provided for any of the next to be operated. If the element is short, steps. Thus for the two sets of sixteen circuits relay KSI or KS2 remains in its normal posi mentioned, relay P4 may be replaced by a pair of relays HA and HE, having their windings 45 tion and the relay P is not operated, and the circuit prepared for the next counting relay in connected in parallel and their contacts a in se cludes wire 56 or 51 and a back contact b of the ries, as shown in Fig. 4, likewise relays P5 and P5. relay P. In case a pilot relay such as P2 is Any of the thirty-two circuits thus provided may omitted, as in the case being described, the cor be branched over front and back contacts of re responding wire such as wire 22 is connected lay P‘! to provide circuits for two~S relays, as is directly to wire 56 or 58, and as shown, relay 3 obvious. responds to the third impulse only if the second The pilot relays have a dual function. When two stations, two sets of circuits for sixteen S relays, each set like the one shown, but connected the coding unit is in the receiving condition,‘ with relay E picked up, the relays P are picked up one at a time in response to corresponding long ele ments of the code as received, and current is supplied to wire 2| by relay CR to pick up the selected relay S on the eighth step of the code. The relays P also serve to condition the coding ‘unit to transmit a code. That is to say, they may be set up in any desired combination and the corresponding S relay energized when the system is at rest by the operation of a starting button or code determining relay to initiate the transmission of a code, in which case the P relays determine the pattern of the station code call, as already mentioned. The step-by-step operation of the apparatus of Figs. 1A and 1B in receiving an indication code will now be described. It will be assumed that the code received is one transmitted from station No. 1 as above described, in which steps one and three to six are long steps, and steps two and ~seven to ?fteen are short, and it will be under step is short, . .It follows that relay 8 responds to the eighth impulse of a code to pick up relay CR only when the relays P have been set up in a, combination representing the code call received by the relays l to ‘I and KS. If the ?rst code element is long, as assumed so that relay E is picked up, relay 8 completes a circuit extending from terminal B at contact 1‘ of relay LB, contact 0 of relay 8, contact b of relay E, back contacts 0 and j of - relays ST and M, to wire 2|, and thence as already described in connection with Fig. 13 over front contacts e of relays P3-P6 and the winding of the selector relay OIS to terminal C. Relay OIS is thus energized in multiple with relay CR and the closing of front contact a of relay CR completes a stick circuit for holding both of these relays picked up until the end of the code. When relays OIS picks up, a branch of its circuit extending from terminal B over con tact b of relay E to wire 9 is closed at contact a of relay OIS through the winding of relay OID to terminal C, whereby relay OID is energized. 75 stood that the o?ice line relay R responds to the ! ' i 17'. 2,409,696 The closing of contact a, of relay 0! D then com pletes a circuit for operating the indication relay K1 in accordance with the character of the sev 18 the apparatus of Fig. 1B, with reference more particularly to the upper right-hand portion of that view, which-shows circuits controlled by the enth element, this circuit having a connection to buttons for controlling the relays P2‘~—P6 as re terminal B at wire 9 whereby relay ‘Kl is ener quired by various code calls. The front contacts gized in thenormal or reverse direction accord b to e, etc. of buttons PB, which provide a con ing to the position of contacts e and f of relay P7. nection from wires ‘H to wire l3—16, correspond The indication relays may be ‘of the ordinary to the long; elements in each of the ?fteen code stick polar type, but preferably are of the type cajlls setup by the operation of buttons IPB to shown in Letters Patent of the United States to 10 IEPB. The sixteenth code call, assigned to but Agnew No. 2,301,992, granted November 1'7, 1942, for Electrical relays,.whic-h relaysare operable to their picked up and released positions by cur rent of normal and reverse polarity, respectively, and are adapted to' remain in their last operated position when deenergized. Contacts b to z‘, inclusive, of relay OiD prepare circuits for operating the relays K connected ton IBPB, does not require the energization of any of the relays P3 to P6. It follows that the code combination assigned to each of the panels may be readily identi?ed from the drawings. Terminal B is connected to wire I‘! only when the system is at rest, or at the end of a relatively long time interval following the sixteenth im pulse of a code, as already explained, under which thereto in accordance with the character of steps condition the operation of any of the buttons eight to ?fteen of the code. For example, the 20 except IEPB extends the connection from ter operation of relay R to the right in response to minal B to one or more of the wires 'l3-'-'l6 and the ninth impulse connects terminal B to contact thence through the upper windings of the corre a of relay KS2, which relay is then held deener sponding relays P to terminal C, thereby ener gized in its normal or reverse position to store the gizing a relay P for each long element of the character of the eighth element. Relay l picks selected code call. The energized relays P by up, completing a circuit from terminal B to closing their contacts 0 complete a connection terminal 0 over contacts a and c of relay KS2, from wire I‘! to wire I 5 toipick up relay ST. The including contacts g of relays CR and E, contact operation of button IBPB completes a connection 7‘ of relay l, wires 48 and 45, contact b of relay from wire I‘! over its contact b to wire IE to 01D and the winding of relay NWK, whereby 30 pick up relay ST without operating any of the relay NWK is energized normal or reverse to cor relays P, the code call for this button comprising respond with the position of relay KS2. The op four short steps. eration of relay R to the left in response to the When relay ST picks up, a circuit is closed tenth impulse opens the circuit for relay NWK from terminal B at its front contact 0 over back and connects terminal B to contact a of relay contact 1‘ of relay M to wire 2| to pick up the KS], and also restores relay KS2 to normal and relay S which corresponds to the combination energizes relay'2, while relay KS2 is held deener~ set up by the relays P, opening back contact it gized in its normal or reverse position to store of the operated relay S to extinguish the indica the character of the ninth element. Relay '2 tion lights of the selected panel. If the relays P completes a ‘circuit from terminal B to terminal have been positioned properly this panel will be C over‘contacts a. and c of relay KSl, including the one containing the operated button. That contacts 1‘ of relays CR and E, contact 1‘ of relay is to say, relay 015 will be energized only if 2, wires 49 and 4'1, contact 0 of relay OID and the each of the relays P3 to P5 pick up in response winding of relay LHK, whereby relay LHK is to the operation of button I PB, whereupon ter energized normal or reverse to correspond with ‘ minal B at contact f of button IPB will be con the position of relay KSl. nected over contact 9' of relays OIS to wire 28 The operations occurring during the remain and thence over contact a of relay ST, to pick ing steps of the code are similar to those ole up relay M, thereby setting relay '1‘ into operation scribed, as will‘be readily apparent. It follows to transmit the code as already described. that on steps eight to thirteen, respectively, re It is to be understood that the connection to lays K'I, NWK, LHK, RWK, RHK and TK will wire 28 over contact 1‘ of each of the starting but each be operated to a position re?ecting that of tons IPB to E?PB includes contact 9' of the cor the corresponding indicating relay at station‘No. responding S relay. It follows that relay M will 1. Steps thirteen to ?fteen are ?xed short steps not pick up if, due to a fault, the pilot relays in the code Ibeing described, but additional indica- . 55 P do not occupy the positions required for the tion relays Kl3 to Kl5 may be provided for indi code call identifying the operated starting button. cating the character of these steps if required. When relay M picks up, its front contact 6 The operation of relay R to the left in response connects terminal B over wire [9 and the lower to the sixteenth impulse picks up relay l6, and windings and contacts a of the energized relays contact b of relay l6 completes the circuit for 60 P2 to P6 to wire l8 and thence to terminal C operating relay K|5 to a position in accordance at back contact 0 of relay E, and it follows that with the character of the ?fteenth element. Re. the operated button may be released as soon as lay l? is not provided with a stick circuit and relay M picks up to initiate the code. releases after a short interval. Relay R. re The condition of relays P2 to P6 cannot be dis— mains in its normal position, consequently relays turbed by further operation of any of the starting L2, LP and LB release in that order. Relay LB buttons PB because when a code is being sent releases relays CR, E, OIS and OID, and relay or received, terminal B is disconnected from E releases the energized P relays, thereby placing wire l7. the apparatus in condition to receive a new code. As previously explained, when relay M is picked Relay LB also deenergizes relay Ll, which is the 70 up, wires 3l—3'l afford connections over contacts last to release. The release of relay L'l connects d of the counting relays to wires 60, 6! , ‘iii and 'H terminal B to wire ll, thereby placing the ap for governing the operation of relay T to generate paratus in condition ‘to initiate the transmission the ?rst seven elements of the code, the character of a new code. ' . , . . of the variable elements being determined by the Considering now the transmitting condition of positions of the contacts d of the pilot relays P 2,409,696 19 in the circuits. At the beginning of the eighth step, contact b of relay CR picks up to shift the circuits for relay T to contacts e of the counting relays and wires 38-45, and thence over contacts I) to i of that one of the selector relays 01S to OIGS which is energized, and contacts of the 20 ilarly, when button 3PB or APB is operated, the opening of back contact at of the operated button prevents the energization of wire ‘E5 by operation of any higher numbered button. In place of back contacts in the sets of code determining contacts, back contacts of the P relays may be used with the same e?fect; thus back contacts I control levers of the corresponding panel to wires and g of relay P3, which open in response to the (ill, 6|, I!) and ‘H, or directly to wire 6|] or 6| operation of relay P3 by any of the buttons when a control step is idle, and determines the 5PB—8PB, prevent the energization of wires ‘M character of the ninth to ?fteenth elements, in 10 and 15 by operation of any higher numbered but the manner already pointed out. ton. It will be clear from the drawings that the When relay T drops in response to the ener sets of code determining contacts are connected gization of wire 45 to transmit the ?nal impulse to the conductors 13-1’! in such an order that of the code, it remains released. Relay R there they are eiiective only‘one set at a time, in a fore remains in its normal position, and relays ?xed order of code superiority. ' l6, L2, LP, LB and LI release in that order. It is believed that the modi?cation of the code Relay LB releases relays M, CR and the energized determining circuits to provide code calls of ?ve selector relay S, and then relay M releases the or six steps as required for the control of addi energized relays P. Relay Ll, which is the last tional stations will be obvious from the circuits to release, connects terminal B to wire H to 20 as shown. Thus, for example, to control thirty render the buttons PB e?ective to control the two stations, two groups of sixteen contact sets initiation of the next code. each may be used, each similar to the one shown It is to be noted that each operation of relay '1‘ except that in one group each set will have an to generate either a short or long code element additional contact for energizing relay P2, while 25 is dependent upon the closing of a circuit over the contacts of the other group will be connected one of the wires 31-31 or 38—-45. A failure oi over back contacts I to i of relay P2, as indicated any of the circuits to close would make the ele by dotted lines in Fig. 1B. ment inde?nitely long, allowing the timing relays In certain applications of the centralized traffic to release as at the end of the code to reset the control system of my invention, particularly in transmitting apparatus in its normal condition. 30 connection with the control of train movements A similar release at the receiving station pre on single track railroads, it may be preferable to vents the registration of the uncompleted ele“ provide for the storage of codes at the control ment. of?ce so that when several starting buttons are It may readily occur that an indication code operated in a rapid sequence the codes will be will be initiated by a station at the same time transmitted in order without further attention, that a control code for a different station is as in the system of my prior patent. This may initiated. Normally the control code will take be accomplished by the provision of a code de precedence by reason of its short ?rst element, termining relay CS for each panel, each con but if due to a fault, the short ?rst element is trolled as shown in Fig. 3. not properly transmitted the station transmitter In this modi?cation the contacts I) to ,f of each will retain control of the line to deliver a long starting button are replaced by similarly func ?rst element. If this occurs, the o?ice relay E tioning contacts of the associated relay CS in the will pick up in response to the'second impulse circuits of Fig. 1B, each starting button having as in the case of a normal indication code, re only a single contact a. In this modi?cation a leasing the of?ce relay M by the opening of back 45 storing relay such as OICS is picked up at once contact h of relay E. Those relays P at the o?ice in response to the operation of the associated which were picked up to initiate the code will button IPB regardless of the condition of the now release, due either to the dropping of relay coding apparatus, and is then held energized over M or to the reversal of polarity of the current 50 the stick circuit extending to terminal B at back supplied to their stick circuits over wires l8 and contact 111. of the associated selector relay OIS. 19, when relay E picks up. It follows that the When wire I‘l becomes energized, contacts I) to f oi?ce apparatus will be conditioned at the be» of the lowest numbered one of the operated re ginning of the second step to respond to the lays CS will be eiiective to operate the P relays received code, that is, to pick up the relay P for 55 as required to pick up the associated selector any of the steps two to seven in accordance with relay S and to connect terminal B to wire 28 the code as received. It may also happen that two or more starting buttons are operated at the same time. The to initiate the code as described in connection are so arranged, however, that irrespective of the number of sets operated, only one set of code determining contacts is effective to determine is picked up and its contact m inserts back con with the circuits of Fig. 13, as will be readily apparent. In response to the operation of relays code determining contacts controlled by the 60 P3 to P6 by relay OlCS for example, relay OIS starting buttons and connected to wires 72-46 the code and no interference occurs, due to the provision of novel circuit arrangements as will now be explained. By reference to the drawings it will be seen that each odd-numbered button PB has a front contact e for energizing wire 15, and that wire 16 must be deenergized to set up the combination for any even-numbered button. Each of the lat ter has a back contact e in the connection to wire '58 which opens when the button is oper tact a of relay IS in the stick circuit for relay OICS as shown in Fig. 3, whereby the circuit is opened to release relay OICS in response to the 65 transmission of the sixteenth impulse of the cor responding control code, to allow the next ener gized relay CS in order to initiate the next code to be transmitted. A contact 7‘ of the associated delivery relay 0 ID 70 provides a connection to terminal B which serves to prevent the release of relay OICS by relays OIS and I6 at the end of an indicationcode, in the event that the starting button IPB is operated and relay OICS picked up, during the reception ated, to prevent the energization of wire 16 by ' operation of any higher-numbered button. Sim 75 of an indication code. 2,409,696 21 ' ‘Referring now to ‘Fig. 23, it has ‘already been explained that this view together with Fig. 2A shows an arrangement suitable for use at a ?eld location having a limited number of controlled devices within the capacity of a single o?lce con trol panel such as the one shown in Fig. 13, these devices ‘being those required for the control of a singletrack switch IW, and a group of signals LH and RH, located atone end of a passing siding on a single track railroad, as indicated by the track plan shown. Suitable circuits for the safety con trol of such devices are well known, one arrange ment being shown, for example, in my prior pat ent hereinbefore referred to, and accordingly these circuits are shown herein only in diagram matic form, to indicate how a typical group of tra?ic governing devices may be controlled by 22 relays, comprising a change relay ‘ICH, a storing relay ICS, and a. station sequence relay SS, as will now be described. It has already been explained that an indica tion code is initiated by picking up relay ICS to connect wire I 1 to wire l5, and that relay lCS may be picked up by manual control by trans mitting a control code to station No. '1. An indi cation code is also initiated automatically, in re— sponse to a change ‘in position of any of the in dicating relays which control the character of steps seven to ?fteen of the code. In the speci?c ' arrangement shown, a relay R1 controls the char acter of the seventh element, the eighth and tenth elements are controlled in accordance with the positions of contacts d of switch indication relays NWP and RWP, and the signal relays LHR and RHR similarly control the ninth and eleventh elements. The track relay TR for the detector code by means of stick polar relays. Wires 464-55 leading to the coding unit of Fig. 2A provide cir cuits for the control of eight stick polar control 20 track section including switch IW‘ controls the relays, of which but three are required for the character of the twelfth element by the operation simple layout shown, namely, the switch control of a storing relay TS. relay WS which governs the operation of the Relay ICH, as shown, is normally held ener~ switch machine ISM, and the signal control re gized over a stick circuit extending from terminal lays LHS and RHS which govern the signal re~ 25 B at contact b of relay RHR over contacts b of lays Llm and RHR, to clear the signals for the the indicating relays mentioned, and the front desired direction of trai?c movement and for contact a and winding of relay ICH to terminal putting the signals manually to stop. C. Relay iCH is released in response to» a change It has also been explained that the apparatus in position of any of these relays to extend the of Fig. 2B is arranged as required at station N o. 1 by connecting wires 22-4‘! to wires 56-59 in such a manner as to render the counting relays selectively responsive to the code call set up by operation of the starting button IPB of Fig. 1B. It will be apparent that the operation of the counting relays will be discontinued on one step or another of any control or indication code con taining a different code call. More particularly, the station relay E responds to a short ?rst ele ment, indicating the oilice as the place of origin, and relay CR responds only if the second element is short and elements three to six are long, indi eating station No. 1 as the intended destination, and if relay P‘l corresponds in position to the character of the seventh ‘element as received. since the station coding unit in this case responds selectively to only one code call, selector and de livery relays corresponding to relays OIS and 30 connection from terminal B over its back contact a. and front contact a of a relay SS through the lower winding of relay ICS to terminal C. Relay SS is a slow pick-up relay normally energized over wire I1 and consequently is released when the line is in use and becomes reenergized follow ing the release of relay Ll at the end of a code. ‘ Relay ICS therefore picks up in response to the closing of contact a of relay SS, after the line has been free for a time su?icient to enable relay SS 40 to pick up, and the closing of front contact b of relay ICS connects terminal B at wire I‘! to wire IE to pick up relay ST. In Fig. 2A, wire 28 is connected directly to terminal B, so that relay M picks up at once to initiate the code. When relay 45 LB picks up in response to the ?rst code impulse, a circuit is closed from terminal B at front con tact f of relay LB over back contact a of relay CR to wire l0 and thence over contact 0 of relay lCS OlD are not required, the closing of the contacts through relay I CH to terminal 0, whereby relay f and g of relays CR and E in the circuits includ 50 ICI-I is picked up to reestablish its stick circuit. ing wires 46-55 being suiiicient to indicate the Relay ICS is held energized until the ?nal step selective response of the coding unit. In‘other of the indication code is transmitted, over a stick respects the circuits for controlling the stick polar circuit'including its contact a and wire 20, ex relays such as WS are similar to those for the in tending to terminal B at‘ back contact a of relay dication relays K of Fig. 13, as will be readily " 55 l6, and thus maintains the coding unit in condi apparent. , tion to initiate an indication code repeatedly, if Although the apparatus of Fig. 2B is arranged necessary, until such code is transmitted ‘in its speci?cally for use at only one location, namely, \ entirety. at station No. 1, it will be readily apparent that Relay CR disconnects terminal B from wire ID similar arrangements may be provided at each on the eighth step, consequently a change in the other location for which nine controls or indi 60 position of any of the indicating relays occurring cations suii'ice, and at each such location one ‘or after relay CR picks up is eifective to release relay more of the wires 23 to 25 will be connected to ICE to effect the transmission of a second code. wire 56 or 57 instead of to wire 58 or 59,'the con An indication code follows each control code nections at each such location being arranged in ‘ received by the station, even though the control a distinctive pattern to render the counting relays code causes no change in the position of any of selectively responsive to the code call set up by the the indicating relays, for the reason that during corresponding one of the starting buttons PB. each contro1 code received, the delivery wire 9 Furthermore; the connections of wires 33‘to 36 is connected to terminal B as already explained, by which relay T is controlled will be arranged at ‘ each station in a pattern corresponding to the 0 and as will be clear from Fig. 2B, relay ICS is thereby energized over its upper winding to estab~ connections for the counting relays at that sta~ lish the stick circuit including its lower winding. At the end of a control code, ‘wire 9 remains con tion. ‘ . ' The initiation of indication codes by the ap paratus of Fig.2B is governedby a group of three ‘ nected to terminal B until after relay It releases‘ to reestablish the connection to terminal B at 2,409,696 23 wire 20, consequently relay ICS remains picked up. Relay TS provides means for insuring the trans mission of an indication of the occupancy of the track section controlling relay TR, even though the section is vacated before the indication is transmitted. Relay TS picks up in response to the release of relay TR and if relay TR then picks up again, relay TS is held energized over a stick 24 The circuits for operating the stick polar relays such as relay 5W8 di?er from those of Fig 2B in that they are selected over contacts of the associated delivery relay 5D, and they are conse quently similar'to those for the indication relays K of Fig’. 1B, already described. The step-by-step operation of the apparatus of Figs. 2A and 20 in response to a control code transmitted to station No. 5, for example, will be described. circuit including back contact b of relay [CI-I 10 now Assuming the system to be in its normal at rest condition, the operation of the office starting but ton 5PB picks up relays P2, P4 and P5 of Fig. 1B, mission of the corresponding “track occupied” energizing relay ST of Fig, 1A to pick up relay code, provided relay TR is then energized. When 05S, thereby connecting terminal B to wire 28 to relay ITS releases, its contact ‘b operates to re pick up relay M of the office coding unit to initiate lease relay iCH to effect the transmission of a the code, which differs from the one already de "track clear” code. scribed in detail, by having a short fourth step. In installations having a large number of sta It is to be understood that the coding unit for tions and controlling heavy trailic it may happen stations 5 to 8 is the only one responsive to codes that the number of changes occurring is suffi 20 having a long third step and a short fourth step cient to keep the apparatus in continuous opera and consequently the only one at which relay 5 tion for considerable periods of time, resulting in picks up. Relay E, Fig. 2A picks up in response undue delay in the delivery of codes from inferior to the short ?rst step and prepares a circuit closed stations if the stations are given access to the line when relay Ll releases on the long fourth step, in a given order of code superiority as described. 25 over wire 65, to pick up relay P5, Fig. 2C, Relay Relay SS provides means for preventing undue Ll reverses relay KS1, and the closing of front delay under this condition. Assuming for ex contact I) of relay P5 connects wire 25 to wire 59 ample, that several stations initiate codes at the extending to terminal C at the reverse contact I) same time, it will be evident that the codes will of relay KSI so that relay 6 of the station coding be transmitted in a ?xed order“ each relay CS 30 unit picks up in'unison with the office relay 6, which picks up at the beginning of the series of which is energized over a similar circuit. In a codes being released at the end of its code, until similar manner, relay P6 of Fig, 2C is picked up all are released. When wire I‘! becomes energized on the sixth step to prepare a circuit for relay 1. at the end of each code, a relay ST will be picked At the o?ice and at the location of stations Nos. up to initiate the next code before relay SS 5 to 8, relay I picks up on step seven, and then on has had time to close its contact a. Consequently step eight, relays 8 and CR pick up, and at the until relay ICS picks up, and then over front con - tact d of relay lCH, releasing after the trans no additional relays CS can be picked up. In other words, each station unit is allowed to trans mit only one code if some other station has a code stored for transmission, for the reason that its relay CS cannot be picked up in response to a change in station conditions unless the line has been free for an interva1 somewhat longer than ?eld location terminal B is connected to wires 21 and 9 to pick up relays 5S and 5D, in turn, and to operate relay MCR in accordance with the 40 character of step seven. The closing of contact a of relay 5D completes a circuit from terminal B through the lower winding of relay 50S to ter minal C, so that relay 50S picks up. The closing of contacts I), c and e of relay 5D connects relays 5WS, 5LHS and 5RHS to the wires 48, 49 and 5| leading to the coding unit to prepare circuits for operating these relays in accordance with the character of steps eight, nine and eleven, re 50 spectively, as already described. When the the normal interval between successive codes. Referring now to Fig. 20, this view together with Fig. 2A shows the apparatus required at a ?eld location at which the number of controlled devices exceeds the capacity of a single o?ice panel, as for example, would be the case in the control of a remotely controlled interlocking as indicated by the track plan in Fig. 11 or my prior ‘ ' sixteenth step is reached, the apparatus restores to normal in the usual manner, but relay 5CH patent. In Fig. 20 as shown, it is assumed that remains picked up over a stick circuit extending the location includes four groups of devices each from terminal B at back contact is of relay 58 similar to that of Fig. 2B, comprising stations Nos. 5 to 8, inclusive, of which only station No. 5 is .55 over its own front contact a and lower winding to ' terminal C. shown. If button 8 PB had been operated in place of The code combination required for each of the button 5PB, for example, steps ?ve and six of the different stations may be readily ascertained from code would have been short steps and relays P5 the connections of the starting button contacts as ' shown in Fig. 1B. In View of the description of 60 and P6 would have remained released, resulting in the operation of a selector relay 8S and the that view and of Fig. 23 already given, it will be ' corresponding delivery relay 8D, not shown, to readily apparent that the apparatus of Fig. 2C deliver the code to station No. 8. If, however, is connected to respond to the code calls set up due to a fault, relay P5 or P6 at the station fails by the operation of buttons 5P to 8P, in which step three is long and step four short. These ‘65 to pick up on the corresponding long steps of a code for station No. 5, relay 8S is not operated code calls differ one from another only in respect ‘ for the reason that in that case the station count to steps ?ve and six, and the two relays P5'and ing relay 6 or I will not be operated. P6 provide circuits for the selection of four relays The transmission of indication codes by the 58 to 88 similar to the correspondingly numbered 70 apparatus of Fig. 2C is effected by the provision selector relays 05S to 08$ of Fig. 1B. of a pair of relays such as the relays 50H and 50$ With the apparatus of Fig. 2C in the receiving for each group of devices, together with a single condition it is clear that any one of the four codes relay SS, which relays function like the corre to which it is adapted to respond will su?ice for the operation of the maintainer’s call signal MC, accordingly this feature is arranged as in Fig, 23. I 75 sponding relays of Fig. 2B. In Fig. 20 each relay CS is provided with addi 25 2,409,696 tional contacts for operating the station pilot re lays P over circuits similar to those controlled by the starting buttons PB in Fig. 1B, in other words, ' energized communication circuit comprising two line‘ wires, a‘ plurality of line relays of the stick polar type each arranged to be held locally in its they function as described in connection with re ~ normal or reverse position when deenergized and lay OICS of Fig. 3, except that the check circuit including wire 28 is omitted. It follows that if having a winding connected across the line wires, one such relay being located at the of?ce and one at each station, ‘a plurality of code transmitters relay 503 is picked up, the release of relay Ll at the end of the control code described completes including one at the oflice and one at eachista~ tion each effective when initiated to deliver to the line wires a code of‘impulses of alternately op a circuit from terminal B at wire I‘! over contacts 02 and 'e of relay 5C8, wires 15 and 16 through relays P5 and P6 to terminal 0 so‘ that relays P5 and P6 pick up, extending the connection of ter minal B over their contacts 0 to wire l5 to pick posits polarity characterized by the relative lengths of the time intervals between successive impulses, each impulse acting to operate said line up the station starting relay ST, which inturn picks up relays 5S and M to initiate an indication relays in unison to normal or reverse, code re 15 sponsive means controlled by each line relay in code in which steps one, ?ve and siX are long and 7 steps two and four are short, to select the otlic'e . accordance with the characteriof said codes, and means‘ controlled locally by each line relay for panel for station No. 5, and in which steps seven restoring such relay to its normal position in the to ?fteen are controlled by a group of indicating event the relay remains reversed for a prede relays selected by relay 58. It will be clear that 20 termined time interval which is longer than any in Fig. 2C, the connections from wire I‘! to wires of the time intervals in- said code. 75 and ‘H3 are so arranged that if the relays 508 to 8C5 are all energized at the same time, the corresponding codes will be‘transmi‘tted one at a 2. In a remote control system, an mice‘ and one or more stations connected by a normally de _ energized communication circuit comprising two time in order without interference. Relay SS, in - ‘line wires, a plurality of line relays of the stick Fig. 2C controls the connection to terminal 0 for polar type each arranged to be held locally in its the upper winding of each of the relays 5C8 to normal or reverse position when deenergized and BCS, and functions as described in connection having a winding connected‘ across the line wires, with Fig. 23, so that codes for indicating changes one such relay being located at the o?ice and one occurring after the relays CS have been picked up 30 at each station, a plurality of code transmitters‘ will be stored by the relays CH and the corre~ including one at the crime and one at each station‘ spending relays CS cannot be reenergized until each including an impulse transformer normally ‘ each of the relays CH energized at the beginning of the series has transmitted its code. In the event the office and one or more stations initiate codes at the same time, the transmission of the second impulse by the o?ic'e transmitter to make the ?rst step short will open the stick circuit for each ?eld station relay M, if closed, and will also pick up relay E at each ?eld location, and’ at each location such as that of Fig. 2C at which one or more relays P have been picked up, these relays will be released due to the reversal of the polarity of the current supplied to their stick circuits as already explained in connection with the similar relays of Fig. 13. Consequently only’ the o?ice transmitter remains in operation and the apparatus at each station is in proper condition to respond to a control code containing the disconnected from the‘line wires, and a master relay, means controlled by each master‘ relay when energized for connecting the associated im pulse transformer across the line‘ wires and for periodically‘ energizing said transformer to ‘de liver to the line wires a code of impulses of alter= nately opposite polarity characterized by the time spacing of successive impulses, each impulse act' ing to operate the line relays in unison to normal or reverse, code responsive means controlled by each line relay in accordance with the time spac-v ing of said impulses, and means controlled by each line relay acting to automatically‘ restore the relay to its normal‘ position if it is operated to its reverse position by an impulse which is not followed by other impulses to constitute a code. 3. In a remote control system, an oi?ce and corresponding station code call. In Fig. 20, the 50 one or more stations connected by a normally de energized communication circuit comprising two selecting relay 8S similar to relay 58 shown, but line‘ Wires, a plurality of line relays of the stick this relay will not be operated unless the corre polar type each arranged to ‘he ‘held locally in sponding code call is received so as to enable the‘ its normal or reverse position when deenergized counting relays to respond to the ?rst eight im 55 and having a winding connected across said line pulses of the code. ' Wires, one such relay being located at the of?ce release of the P relays prepares a circuit for a ' In view of the similarity of Fig. 2C to Fig. 1B, _ it will be readily apparent that additional relays ~P controlled over one or more of the steps two to seven of the code may be provided to expand the capacity to eight, sixteen, thirty-two, or‘ sixty~ four stations, at the same ?eld location, and that any of the code calls not used at a given location may be used at other locations. Although. I have herein shown and described only one form of remote control apparatus en - bodying my invention and several‘ modi?cations and one at each station; a transmitters including one at at each station each effective deliver to the line Wires‘ a plurality of code the of?ce and one when initiated to series of induc tively generated impulses of alternately op posite polarity each’ impulse ‘acting to operate the line relays in unison to normal or reverse, said codes being characterized by pausesgfollow ing certain‘ of the impulses during which the‘ line relays are held locally in their last operated posi tions, code‘ responsive means controlled by each thereof, it is understood that various changes and line relay in accordance with the character‘ of modi?cations may be made therein within the codes, and means‘ controlled by each relay scope of the appended claims without‘ departing 70 said acting to automatically restore the relay to its from ‘the spirit and scope of my invention. normal position if it is‘operated to a reverse posi-v Having thus described my invention, what‘ I tion by an impulse which is not followed by other claim is: impulses to constitute a code. 1, In aremote control system, an oi?ce and one 4'. In a remote control system,‘ an oi?ce and or more stations connected by a normally de 75 agstation connected by two line wires, ,a‘line; re 2,409,696 27 lay of the stick polar type connected across said line wires at the o?ice and also at said station, a code transmitter at the oiiice and at the station 28 line relay associated therewith is operated by an impulse delivered by another transmitter during a pause in the operation of said associated trans mitter. '7. In a remote control system, a plurality of sta line wires a series of inductively generated im tions connected by two line wires, a two position pulses of alternately opposite polarity to operate polarized line relay having access to said line the line relays, said codes being characterized by wires at each station, a code transmitter at each pauses following certain of the impulses during station having a contact operable to normal and which the line relays are held locally in their reverse positions to deliver codes of impulses of 10 last operated positions, and means for discon alternately opposite polarity to said line wires to tinuing the delivery of impulses by each code operate the line relays to normal and reverse each effective when initiated to deliver to the ' transmitter during any pause in its operation when transmitting a code if the associated line relay is operated during said pause by an im pulse received from said line wires. 5. In a remote control system, an office and a station connected by a normally deenergized com munication circuit comprising two line wires, a line relay of the stick polar type at the office and at said station each arranged to be held locally in its normal or reverse position when deenergized and having a winding deriving its energization from impulses delivered at times to said line wires, a code transmitter at the office for deliver ing impulses to said line wires to momentarily~ energize said line relays, means at the o?ce for actuating said code transmitter periodically to deliver to the line wires a series of impulses of positions, the codes being characterized by pauses between selected impulses during which the line relays are deenergized, means associated with each line relay for maintaining it in the position to which it is operated by each impulse, until the next impulse is received, and interference pre venting means controlled by each line relay and by the associated transmitter relay comprising a circuit which is closed either over their normal contacts or over their reverse contacts as long as the line relay responds to the code operation of such transmitter relay but which is opened when the line relay is operated by an impulse re ceived during a pause in the operation of the as sociated transmitter relay, the opening of said circuit being effective to discontinue the operation of said transmitter relay. alternately opposite polarity, stepping means con 8. In a remote control system, two coding units trolled by the oi?ce line relay for counting 3O each including a receiver selectively responsive to the impulses and for controlling said code trans multiple element codes including selecting ele mitter, thereby interposing pauses following cer ments and a transmitter controlled by the associ tain of the impulses during which the line relays ated receiver for transmitting such codes, a plural are held locally in their last operated positions, ity of pilot relays in each coding unit including code responsive means comprising stepping means 35 one for each selecting element of a code, a plural controlled by the station line relay to count the ity of selecting relays in each coding unit includ impulses, and means selected by said stepping ing one for each different combination of said se means which is selectively controlled in accord lecting elements in a code, energizing circuits for ance with the time spacing of the impulses. said selector relays including contacts of said pilot 6. In a remote control system, a plurality of 40 relays, there being one such circuit for each differ stations connected by a normally deenergized ent arrangement of said pilot relays in their communication circuit comprising two line wires, operated or released positions, a ?rst relay in an impulse transformer normally disconnected each coding unit selectively responsive to a ?rst from the line wires effective when operated to re verse and normal positions to supply impulses of 45 element in a code provided such element is of a particular character identifying the code as one reverse and normal polarity to the associated im transmitted by the other coding unit, means rend pulse transformer, located at each station, a stick ered effective when said ?rst relay is energized for relay at each station effective when energized to energizing each pilot relay of the associated coding connect the associated impulse transformer to the line wires and to operate the associated trans 50 unit or not depending upon the character of the corresponding selecting element being received, mitter relay repeatedly to reverse and normal and for then energizing that selector ‘relay the positions to deliver a code of impulses of alter circuit for which includes a closed contact of each nately opposite polarity through such impulse pilot relay, means in each coding unit effective transformer to the line wires, each such code be ing characterized by pauses following certain of 55 only when such coding unit is in a normal at rest condition for operating the pilot relays the impulses, a line relay at each station of the as required to prepare the circuit for a parti stick polar type operable to reverse and normal cular selector relay of such unit and for then positions in response to such impulses, means for energizing such selector relay, and means holding each line relay locally in its last operated normal or reverse position during said pauses, 60 controlled by the operated selector relay for setting the associated transmitter into operation starting means for each stick relay effective only to transmit a code having a ?rst element to which when said communication circuit is in its normally said ?rst relay of the other coding unit is respon deenergized condition for picking up such stick re sive, and selecting elements of which the char lay to set the associated transmitter relay into operation to deliver its code, and lockout means Ci 9"' acter is determined by the positions of said pilot relays to thereby energize the corresponding pilot effective in the event a plurality of said trans relays and selector relay of the other coding mitter relays are set into operation at the same unit. time to discontinue the operation of all but one, 9. In a remote control system, an of?ce and a comprising a holding circuit for each stick relay plurality of stations connected by a normally including its own front contact and contacts of deenergized communication circuit comprising the associated line and transmitter relays by two line wires, a code transmitter at the office which one stick relay is held energized for the and at each station, each comprising an impulse duration of its code, and each other stick relay is transformer normally disconnected from the line released to terminate the delivery of impulses Wires and a transmitter relay effective when 75 by the associated transmitter in the event the 29 2,409,696 operated to reverse and normal positions to sup ply impulses of normal and reverse polarity there to, a plurality of stick relays including one at the o?ice and one at each station each serving as a master relay which when energized connects Cl 30 said receiving means is responsive, circuits con trolled by said master relay for maintaining the energized pilot relays and said selector relay the associated impulse transformer to the line wires and operates the associated transmitter relay repeatedly to reverse and normal positions to deliver a code of impulses of alternately oppo site polarity through'the transformer to the line 10 wires, each such code being characterized by pauses following certain of the impulses, a plural ity of line relays of the stick polar type including one at the oilice and one at each station, each picked up until the end of such code, and means controlled by said receiving means for governing the character of the selecting elements in the transmitted code in accordance with the positions of said pilot relays and for governing the char acter of said additional element in accordance with the position of a movable device selected by the energized selector relay. 11. In a remote control system, a coding unit for transmitting and receiving codes each of which includes a group of selecting elements ar responsive to the codes supplied to said communi 15 ranged in different patterns in different codes, a cation circuit, means associated with each such group of pilot relays in said unit including one relay for restoring it to its normal position when for each selecting element, which assume ener said communication circuit is in its normal de gized or released positions in distinctive combina energized condition and for holding it in its last tions to register the code patterns, two circuits operated position during each pause in a code, a 20 for energizing each pilot relay, means effective pick-up circuit for each master relay including when a code is being received by said coding contacts ‘closed only when no code is being de unit for completing one circuit for each pilot re livered to said communication circuit, and a lay the energization of which is required to regis stick circuit for each master relay which includes ter the code pattern being received, such relays its own front contact and which has two branches one of which is closed only when the associated transmitter and line relays are both in their nor mal positions and the other only when these relays are ‘both in their reverse positions, so arranged that each master relay is held energized for the duration of the code delivered by the asso ciated transmitter but only if the associated line relay is not operated by an impulse delivered by being thereby energized one at a time as the selecting, elements are received, starting means for each different code for initiating the trans mission of a code by said coding unit, each effec tive if operated when no code is being received by said unit to complete the other circuit for each pilot relay the energization of which is required to set up the code pattern identifying the oper ated starting means, and means for controlling another transmitter during a pause in such code. 10. In a remote control system, a coding unit for controlling selected devices at the same or at a distant location by distinctive codes, each of which includes a group of selecting elements and an additional element, each of one character or the character of each selecting element in the transmitted code in accordance with the position each in response to a corresponding element of said one character in the received code, stick cir I relay is required for the corresponding code cuits controlled by the receiving means for hold ing each energized pilot relay picked up until the when said coding unit is in a normal inactive of the corresponding pilot relay. 12. In a remote control system, a coding unit for transmitting and receiving codes each of which includes a ?rst element of distinctive char another, the selecting elements being arranged 40 acter and a group of selecting elements arranged in diiferent patterns to select diiferent devices, in different patterns in different codes, a group of said coding unit comprising a series of pilot pilot relays in said unit, including one for each relays including one for each selecting element, a selecting element, which assume energized 'or plurality of selector relays including one for each released positions in distinctive combinations controlled device, a master relay, and code re to register the code patterns, starting means ceiving and transmitting means; means respon for selecting the diiferent code patterns for sive to the operation of said receiving means when transmission each including means for ener said transmitting means is idle for selectively gizing each pilot relay by current of a energizing said pilot relays only one at a time given polarity if the energization of , such end of such code, a circuit including contacts of all of the pilot relays closed after the last selecting element is received for energizing the selector re lay for the code pattern indicated by the positions of said pilot relays, means controlled by said selector relay for controlling the corresponding pattern, said starting means being effective only ‘condition, means for energizing said pilot relays one at a time by current of the opposite polarity each in response to a different selecting element of a given character in a received code to register the code pattern of such code, a stick circuit for each pilot relay closed when such relay is picked up and supplied with current of the proper po device in accordance with the character of the Cl) larity to maintain such relay picked up until the additional element in such code, a plurality of end of the corresponding code, and means con locally controlled contact sets including one for trolled by the ?rst element of a code received each di?erent code pattern each effective if oper when one or more of said pilot relays have been ated when said receiving means is idle to selec picked up to transmit a code having a given pat tively energize said pilot relays as required to form the corresponding code pattern and to com plete circuits for the selector relay for such code pattern and for said master relay, means con trolled ‘by said master relay when energized for initiating the operation of said transmitting means to deliver a code to the line circuit to which ' tern, for reversing the polarity of the current sup plied to their stick circuits whereby such‘ relays ‘ are released and placed in condition to be re energized in accordance with a different code pattern. ‘ LLOYD V. LEWIS.