US2382128A - Telegraph switching system - Google Patents

Description

Aug. 14, 1945.

D. E. BRANSON' TELEGRAPH SWITCHING SYSTEM l Filed Dec. '7, 1943 7 Sheets-Sheet 1 kuni AT Tod/Ngv Auf' 14 1945' D. E. BRANsoN TELEGRPH SWITCHING SYSTEM 'Filed Dec. 7, 19434 7 sxleets--shee'c 2 N m. bri .R .Y s MR f. .23.2 N N NRM M i! i /E .lv 2f #ik P i D. .22:5 hm V.w 36@ B IUUW om 23u: .3.19: Y |IV. :SW6 w n mw v6 om Vwuu-hN QN. \N

:u Sull 3255" A TTORNEV Au" 14 1945 D. E BRAN'soN TELEGMPH swmcnnie sYsTml Filed Dec. '1, 1943 7 Sheets-Sheet 3 unnnllll- Aug. 14, 1945.

D. E. BRANsoN l l TELEGRAPH SWITCHING SYSTEM 7 sheets-sheet `4 Filed Dec. 7, 1943 Aug. 14, 1945.

Il Illll Il Illll Il IIIII Il l.l||| Il Illll Il lllll ll lllll 7 Sheets-Sheet 5 /N VEN TOR D. E, BRA N5 ON ATTORNEY Aug. 14, 1945.

D. E. B RANSON TELEGRAPH SWITGHING SYSTEM H MPH Filed Dec. 7, 1943 '7 Sheets-Sheet 6 v/Al/E/vrclm 0. E. @PAA/50N By wb2/213m.

A TTORNEV D. E. BRANSON TLEGRAPH SWITCHING SYSTEM Aug'. 14, 1945.`

Filed Dec. 7, 1943 7 Sheets-Sheet 7 Y /NVE/VTOR By o. E, RANso/v www f Mm,

A TTOR/VEV Patented Aug. 14, 1945 TELEGRAPH swITcHING SYSTEM David E. Branson, River Edga N. J., .assignor to Bell Telephone Laboratories,

Incorporated,

. New York, N Y., a corporation of New York Application December 7, 1943, Serial No. 513,246

9 Claims. (Cl. 178-4) This invention relates to communication systems and more particularly to automatic telegraph switching systems in which storage controlled telegraph transmitting apparatus at outlying telegraph stations is automatically set into operation for transmitting stored messages from the outlying stations to the central switching station under control of equipment at the central switching station. The object of the present in-,

vention is to provide an improved telegraph switching system having'increased iiexibility in the manner of directing and controlling the transmission therethrough.

In accordance with an exemplaryV embodiment of the invention, the system disclosed in'United States patent application of Branson et al., Serial No. 448,878, filed June 27, 1942, has been improved by` providing multiple outlet4 circuits therefor.

A multiple outlet circuit is a circuit arrangement which may be provided either at'the central switching station or relatively close thereto to which a large volume traflc is directed by a central switching equipment.v In accordance with the present invention means have been provided, ior said stations to which the volume of traflic thereto is suiiicient to fully load more than one transmission path and receiving instrument located at said station, to direct messages to said stations over a plurality of paths.

In accordance with the system disclosed in the said Branson application, means are provided to enable the operator or Aattendant-,at the central switching station to start at will the transmitter associated with the lines extending from the central switching station, provided that line is not engaged inthe transmission of a vmessage from some transmitter to the central switching station. Means are also provided tointerrupt vtransmission fromany transmitter to a centralswitching station and thereafter initiate transmission from any other transmitter. In that application means are also: disclosed for automatically testing they transmitters for stored material available for transmission to the central switching station and initiating transmission exemplary system described in said application,

over the transmitter provided to transmit such message material in rotation one at a time. i

A system disclosed in the said copending Branson et al. application ,provides apparatus vfor automatically directing messages received from one or two transmission'paths individual to each outgoing line are selectable by the switching equipment and each path is provided with storage equipment for storing-messages directed to said line 'for the subsequent .transmission over said line-one at a time'. l

In accordance with the present invention, an additional and Ydiilerent ycircuit is provided to handle messages directed through the switching equipment to some stationor stations which receive alarge number of messages. In accordance With'the exemplary embodiment of the invention-described herein, a. plurality of outgoing lines are provided `which enable `a plurality of transmission paths tov extend from the switching Asystem to a receiving device individual to eachV 4path extending'to Vthe local station over which a large lvolume of tralc is directed. These l additional vtransmission paths are adapted to cooperate with the switching equipment of the system disclosedin said Branson et al. application without requiring alteration thereof and without requiring the use of storage equipment in any of the additional paths.

The foregoingand otherv objects and features of the presentminvention, the novel features of which are specically-set forth in; the claims appended hereto,l mayxbe more readily understood from the following description when read with reference tothe attached drawings in which: i Fig. lla shows a `manner .in which Figs. 2, 3 and 4 should be arranged adjacent one another to show in outline form various circuits and equipment of an exemplary system in. accordance with the `present' invention aswell as to illustrate the routes for thetransmission vof messages through the system;

Fig. 1b shows the manner inwhich Figs. 5, 6, 7 and 8 should be arranged adjacent one another to show the circuit larrangements in detail in an exemplary form of the invention;

Figs. 2, 3 and 4 when arranged as shown in Fig. la show a typical telegraphsystem embodying an exemplary form of the present invention;

Figs. 5, 6, 7 and 8 s how the circuit details of an exemplary embodiment of the invention which cooperates withLthe system disclosedin the above-identiiied application in Bransonet al.

Referring now Ato Figs. 2, 3 and 4` when `arrangedas shown in'Fig. 1a, Fig. 2 shows two `typical'party linesand the stations and `control `equipment associated therewith. One party line is designated 2|0, which comprises a `receiving systems.

channel 211 and a transmitting channel 212. Party line 210 is arranged to operate as a full duplex party line. That is, a party line in which messages may be transmitted to any one of the stations at the same time messages are being transmitted from that or any other station of the party line.

Similarly, party line 260 comprises a receiving channel 261, a transmitting channel 262. Party line 262 may be operated on a half duplex basis; that is, transmission may take place over a party line in only one direction at a time, namely,"

either from any one of the stations of the party line or to any one of the stations of they party line, but not in both directions simultaneously.

Both the transmitting and receiving channels ployed in telegraph signals. Various party lines` and channels thereof may include or comprise any or all of the foregoing transmission systems in any or all combinations of said transmission These transmission systems may also include the usual types of repeating, regulating, controlling and interconnecting equipment normally employed in the respective systems and employed in interconnecting thev various types of systems. Transmission Systems of the various types which comprise partyA lines are operated in a usual and well-understood manner so' a description of the operation thereof need'not be included herein because it would serve no useful purpose and only tend to obscure the other elements of r the features of the present invention.

Each ofthe party lines shown in Fig. 2 extends to a plurality of outlying subscribersV or way stations. It is to beV understood'that it is within Athe scope of this invention to extend lines individually from any one or lmore of the outlying" stations to the central switching station; In this case, certain of the control equipment associated with each of the party lines need not be provided as will be readily apparent to those *I skilled in the art. v

Each of the lines which extends to more than one outlying station is provided with control equipment located at or near the outlying station of the party line. may be provided which is individual to each of the outlying or way stations in case the way stations are rather widelyl separated or the convtrolmay be provided common to a group of outlying stations which are located more closely together. Furthermore, certain control equipment may be individual to certain stations while other control equipment provided for the same partyfline may be common to a vplurality of outlying` stations. A Y

K In the exemplary embodiment of the invention disclosed herein three separate and distinct sets of switching and control systems sometimes referred to as secondary switching vcircuits are aS- It should be under- For example, these i The control equipment sociated with each of the party lines shown in Fig. 2. For example, party line 210 extends to the switching and control circuits or secondary switching centers 213, 214 yand 215. Control equipment 214 is individual to station 219. Control equipment 215 is common to stations 216,

211 and 218, while control equipment 213 is common to stations 220 to 224,*inclusive. l

Each of the outlying stations isi provided with a receiving instrument, a transmitting instrument and control equipment. In the specific system described herein the transmitting equipment comprises a keyboard perforator for perforating paper tape with the signals to be transmitted and a device for transmitting said message in accordance with perforations on the tape.

For example, at station 216 the receiving instrument and keyboard perforator are illustrated diagrammatically and designated 225 in Fig. 2. The transmitting distributor is designated 235, whiley control equipment is designated 236. Similar equipment is provided at the other stations. In addition station 219 is provided with a receiving recorder or perforator 229 for reperforating paper tape in acordance with messages received fromY the system. This reperforator is provided at those stations at which other telegraph lines or circuits terminate so that messages intended for these vother stations connected to these other lines may be recorded at station 219'and then later automaticallyy transmitted over the proper linewithout requiring the time of an operator or attendant to retransmit the message.

In order to transmit messages over the'system, the attendant, or subscriber at the outlying or way stations perforates the message on the paper tape for later transmission over the system. Preceding each message, an address code or group of switching signals is perforated in the tape and following `each 'message an end-of-message or disconnect signal is perforated in the tape. Following the end-of-message signalfthe subscriber can perforate any address signal followed'by another message intended'for the station designated by the address. Following this message and each of the messages, an operator'will then perforate a disconnect signal. In addition, the operator or attendant will usually perforate an end-oftransmission signal in the tape after the disconnect signal following the last message available for transmission from the station.

The attendant or operator at the outlying station will then insert a tape in the transmitter for transmission over the system. At a later time, the transmitter is started to operate automatically or under control of the operator at the central switching station. Thereafter the .message is transmitted to the central switching .station and recorded thereat.

The circuits yof the central switching station are illustrated in Figs. 3 and 4. Fig. 4 shows the originating position or station of the central switching'station comprisinga keyboard perforator 411, monitor receiving instrument 410, transmitter or transmitter-distributor 412, control relays'413 and a director circuit 414.` Fig. 4 also shows a miscellaneous intercept' circuit 421 and a receiving reperforator 426 and tape receptacle 425. A willful intercept-circuit 424 is also shown. This intercepting circuit is provided with a repeating instrument 420 comprising a recorder Vor reperforator 421,` transmitting device'4'22, and a director circuit 423. Fig. 4 also'shows multiple outletcircuits in accordance with the present invention. In the illustration Alx1-Fig. 4, three channels of transmission all" included in the multiple outlet circuits 45B, 4.5i, :452 are provided. These channels extend to' corresponding receiving teletypewriters '460, 46| and 462. Receiving teletypewriters 460, 1461 and 462 may-belocated at the centralswitching ystation or they may be located a short' distance from-the central switching system and connected thereto by means of transmission channels v741i), '411 and 412.

' Each ofthe party `lines terminating atV 'the switching ofiice or central switching station is provided with an incoming `line circuit .322, a receiving only circuit 323, storage repeater 324, and the associated transmitter 325. The incoming line vcircuit 323 causes the messages intended for the centrall station to be recorded on thereceivingk only instrument 323 and causes the messages intended for other stations to be recorded and -reperforatedA by perforator 326. ADirector circuit 321 is associated with transmitter 325 and serves to connect transmitter325 selectively to any of the outgoing line circuits, the lines of which terminate in the central switching station, under control of address characters Areceiving each message.

Each of the party lines is alsoprovided with a transmitter start circuit such as 318, an outgoing line circuit 'and equipment for transmitting messages over party lines.

Briefly, messages directed' to stations over party line 21.8 are transmitted to storage vrepeaters associated Vwith line 2|0 undercontrol of director circuits associatedwith the lines upon 1 Awards the station of the ultimate address.

Figs. 2 vand 3 also show a trunk circuit 29!! comprising two transmission channels 290 and 29|V extendingto a dista-nt central switching station k295. with this ltrunk circuit is substantally the same as that associated with each of the `party lines and ldescribed'above. -except that no transmitter start circuits are provided for the trunk circuits.

Operation of the various circuits Vreferred to above, except the multiple outlet circuits, is described in detail in the above-identified copending patent'application, ,Branson et al., which applieation is hereby made a part of the 'present application as it is fully Aincluded herein. Inasmuch as the respective circuits, referred to above, forming parts of the system disclosed here-in operatein substantially the same manner as described in said identified application of Branson et al., repetition of a more detailed description thereof is not instilled.

Turning now t the detailed showing in Figs; 5, 6, 'l Vand when arranged as shown in Fig lb, it will benoted that Fig.5 shows in outline vform certain portions of the director` circuit together with 'a representation of another Idirector vcircuit, a sequence circuit, and an intercept circuit. Fig. 6 shows the connections to the cross bar switchassociated with two director circuits. Fig. 7 shows the multiple outlet circuit arranged Terminal equipment associated withthree recorders or outlets while .Figfll shows the connections of said circuits with cross bar switch.

It will be readily' understoodby persons skilled in the art that Fig. 7, together with' the connections to the cross bar switcha's shown in'Fg. '8, may be readilyadded tothe system disclosedin the above-identified patent applicationv of Branson et al., by merely addingL these two ilgures either above or below the Iig-uros already .in said application or between any of the I'horizontal rowsof figures of said application providingthe necessary leads are added to andcarriedV across the respective ligure as required.A Such an .additionmay be made -without any change in `fthe disclosure of said Branson et al., application V'and without anyother alteration of any of the circuits disclcsedtherein whereupon 'the `circuits. of said application will operate as described there-` in and cooperate lwith the circuits vdescribed vherein and the circuits disclosed herein will 013-; erate as will be described.. 1 In the exemplary'embodiment--of the `inven-y tion disclosed vin Fig. '7, three printers 125, 14'5 and 155 comprise `three outlets of a multiple outlet circuit. It will be readily understood that any suitable number of such outlets may be pro.- videdas are required by various traililc and other considerations; YIn the usual installationallof the outlets of any lgiven multiple outlet circuit will be located atothe same place and usually in the same room `adjacent one another; This location may be in the same building or even the same room as the central switching'equip-ment. However, this location Will usually be at some short distance from the central switching center .and` connectedjthereto by means `of individual trunk circuits.

While in the ,usual installation all of .-the recording devices associated with the multiple-out let --circuit will be located at the same place and in the same room, it is not necessary that they .be so located. For example, one or more oli-the outlets may be located at some distance from the other outlets :and arranged for night service or for .service at any -other specified interval -by appropriete operation of make-busy keys as will be described hereinafter. i

Furthermore, the circuit connections f to the outlets will usually be all the same fora -given multiple outlet circuit. However, -such arrangement is not necessary and as shown in` Fig. '7,

three diierent modifications of the circuits `ex. tending from the central switching center to the receiving instruments have been shown for purposes of illustration. A v i,

The receiving device may be any suitable type printer or reperforatorv or otherreceiving instrument. In` the exemplary embodlmentvof the invention described herein it is assumed to be a printer oi the type disclosed in United States Patent 1,745,633, granted to S; Mortonet al.,

' February 4, 1930, or 1,904,164, grantedto S. Mortonet al., April 18, 1933, the Vdisclosure of which patents are hereby made part of the' application as if fully .included herein. -As shown `in Fig. '7, printer 12 5- is connected to the centralv switching station by means of a loop or transmission path 1.0i. Loop 101 ext-ends to a repeating relay '124 at the central switching 'center'. Thus,' theiarrangement shown in Fig. 'l ismore suitable for the longer loops. y

The printer is shown connected to-'the cen. tral switching station, also `by `a single -loop 104. In this case the loop is not shown'providedlwith' repeating relay. Consequently, the transmission circuits which cooperate with receiving equipment 165 as shown in Fig. '1 is more suitable for loop circuits of intermediate length, that is, loop circuits somewhat shorter than suitable for `operation as shown by loop Recording instrument 145 is shown connected to the central switching equipment by means of two loops 102 and 103.v The loop circuit 103 coinprises the transmission circuit for the transmission Iof telegraph signals, while the loop 102 is provided for certain control functions which will be described hereinafter.

It will be readily'understood by persons skilled inthe art that repeaters may be connected in loop 104 and also in 103 and 102 if it is so desired. However,v where the distances are short, repeaters will not be employed in these loops as a general rule.

Make-busy keys 121, 141 and 161 are provided for the respective instruments 125, 145 and 165. The make-busy keys will be normally operated to positions shown in the drawings when it is desired to receive messages on the associated receivers. However, when it is desired to cause all the messages to be directed to the other printers of the multipleA outlet circuit, thefmake-busy keys associated with the printers not to receive messages will .be operated to the position opposite to the` positions shown in the drawings. When these keys are so operated, they will cause the messages to be directed to other printers of the multiple outlet circuit or to the intercept circuit 503 if the overiiow key 110 is operated as will be described hereinafter.

Receiving instrument 145 is provided with an additional set of contacts 149 which operate once for each character or code combination received by the printer 145. Contact 149 is employed for control purposes as willbe described hereinafter.

Assume for purposes of illustration that a message addressed to the multiple outlet station at which printers 125, 145 and 165 are located arrives at the transmitting point of the transmitter 528 associated with director 50|.

As set forth in detail in the above-identified application of Branson et al. when the first code of the address arrives over the sensing pins of the transmitter and is sensed it causes the rst fan relays l520 of director 50| to be positioned in l accordance with this code combination. The rst fan relays 520 have been represented symbolically by box 520 in which one relay is shown. Persons skilled in the art however will readily understand that the rst fan relays comprise a group of relays which are positioned in accordance with the elements of the first code of the address codes.

Upon the setting'of the first fan relays 520 in accordance with the first address code one of the code relays 524, 525, y526, etc., will be operated.' Assume for purposes of illustration that relay 525 Will operate. Upon completion of the circuit through the winding of relay 524 the operation of relays due to current flowing in this circuit of the director will cause the succeeding address code stored in the tape of the associated transmitter to be scanned. In addition, relay 523 will operate and transfer thecontrol circuits from the first group of fan relays 520 to a second group of fan relays 52|. Thereafter the relays of this second group of fan relays will be positioned in accordance with the second address code stored in the tape. As in the case of the first group of fan relays the second group of fan relays will generally comprise a group of relays each of which is positioned in accordance with certain elements off-the codeemployed. While only one relay is shown within box 52|, persons skilled in the art will readily understandv this symbolic representation of a group of relays which may be positioned in accordance with a code combination.

Upon the operation of the first and second fan relays acode point 550 is selected in a circuit extending from conductor 550 through the contacts of relay 524 and the second group of fan relays 52| to the test and control circuits 522 of director through the operated contacts of relay 523.

Code point 550 is connected through a crossconnection 55| to anrintercept key 552. vAssume for purposes of illustration that the intercept key 552 is in its normal position as shown in the drawings. Under these circumstances the circuit from code point 550 then extends through the break contacts of key 552 and over conductor 5I I to contacts of relay 1I| of the multiple outlet circuit. Assume first that none of the channels of the multiple outlet circuit are busy. Consequently, relay 1II will be released so that conductor 5II then extends through the back contacts of relay 1I I and the right-hand break contacts of relay 1I4 over conductor 8|3 to battery through the winding of hold magnet 841 of the cross bar switch.

When the multiple outlet circuits are idle, as shown in the drawings, battery will be connected to conductor 5I l. However, when these paths are busy, as will be described hereinafter, ground is connected to conductor 5I I. The test and control circuits 522 first test this lead for a busy condition and if the circuit is idle, as assumed, the test and control circuits 'are'advanced` Next the test and control circuit 522 in cooperation with the sequence circuit 504 will cause the operation of the selector magnet |.l 'I'he operation of the selector magnet Will'then again cause the' test and control circuits to advance and again test lead 5I I, this time for' the polarity of the potential connected thereto and also for the impedance connected between this lead and the source of potential connected thereto. If only a single hold magnet is connected to lead 5II, the test and control circuits 522 as well as other circuits of the director are advanced and cause direct ground to be connected to lead 5| I.

The application of ground to lead 5I I completes a circuit for the operation of the hold magnet 841. The operation of magnet 841 at the time the selector magnet 60| ofthe cross bar switch is operated causes the contacts at the cross-point to -be operated and extend a plurality of circuits or leads between the first channel and the multiple outlet circuit shown in Fig. '1 and the director 50 I.

The operation of the hold magnet 841 in addition completes a circuit for the operation of relay 1 I3 from ground through the operated contacts of hold magnet 841 over lead 8I5 land the left-hand break contacts of relay 1'I4 to battery through the Winding of relay 1I3.

The operation of relay 1I3 connects ground to lead 8 I 6 which extends through the operated cross bar contacts to lead 6I6 and thence through the winding of relay 532 to battery. The dotted line indicates other switching contacts. VRelay `532 of the control relays and circuitsV of director 50| then causes the director circuits to advance which, in turn, releases a sequence circuit 504 land the selector magnet 60 I. The releaseV of selector magnet 60|, however, does not! cause the operated part of the present application.

contacts at the cross-point ofthe cross bar switch to' release. Instead, these contacts arel maintained closed so long as the hold magnet 841- remains operated. v The operation of relay 532 causes the director relays and control equipment to advance and apply ground to conductor 6 I4 through the marginal .relay 529 thereby completing a circuit through the `cross-point contacts and over lead 814 for the operation of relay 1I4. Relay 1|4 in operating completes a circuit for maintaining the hold magnet 841 operated and transfers the holdingcircuit of relay 1I3 `from conductor .8l5 to conductor 5I I. Upon the further advance of the director circuit ground will be removed lfrom conductor 5|| and permit. relay 1|f3 to release. The release ofv relay 1|3 completes a circuit for the operation of relay ,1|2 through the left-.hand .break contacts of relay 1|3 and overjconductor 8|6'and .the cross bar contacts of lead GIG `and operated contacts of relay 532 to ground over lead SI1 and the operated cross bar contact.

Relay 1|2 in operating completesan obvious circuit for the operation of relay 1I Relay 1II in operating completes a circuit for maintaining itself operated over `lead 8| 5 under control of the hold magnet 841. Relay 1|| in operating also causes busy lamp 122 to light to indicate to the attendant at the central switching point that the irst channel of the multiple outlet circuit is busy. Relay 1I| in operating also transfers lead 5I| from the contacts of relay 1| 4 to the contacts of relay 13| and relay 134 thus conditioning the second channel of the multiple outlet circuitfor .the reception of another message should one rbe directed to this station during the time the `first channel is busy.

.Operation of relay 1I2 as described above also connects .ground to lead 8I| which extends through the operated cross bar contacts and over conductor 6|| to the winding of relay 53| and under certain circumstances to the winding of relay 530. Relay 53| of the director circuit 50| operates at this time and causes the director circuit to advance and rst transmit the address characters which preceded the message to station or printing equipment 125 and thereafter the message.

As descri-bed in detail inthe above-identified application of Branson et al., the entire address is transmitted over conductor SI2 preceding the message while only the latter portion of the ad.- dress is transmitted over .lead GIU preceding the message. As shown in the drawings, the transmission path 8I2 which extends through the upper winding. of the repeating relay 124 is connected through the operated cross bar contacts to conductor 6|2. Consequently asshown in the drawings, the entire address will be transmitted to the receiving equipment 125 preceding each message. As will be readily understood by persons skilled in the art,'if it is desired to transmit only a`Yportion of the address to the lreceiving equipment 125 the transmission conductor will be arranged to extend from the upper winding of therepeating relay 124 and through the cross bar switch contacts to lead'6l0. Both arrangements are described in greater. detail in the `aboveidentied Branson et al. application forming a As indicated above, signals are transmitted from the transmitter 529 associated with director 58| over conductor. i I2 through the operated cross bar contacts and conductor 8|2 to the upper Winding of. repeating relay 124. Relay 124 repeatsthe signals over conductor 10| to the selector magnet `12.6 of the receivinginstrument 125. Receiving instrument 125 will then record the message.

Relayfollows the signals and repeats them to the busy lamp.y 12| which lamp flashes during the transmission of signals' over conductor` 10 thus indicating tothe attendant-that the signals arev lbeing repeated Aover this conductor. Relay 41291s connected inseries with, loop 10|. Relay 1,29, hOWevei.- is a differential relay having its winding so connected that duringjnormal operation of the system kthe same current ows through each winding ofthe. relay in such a direction as toneutralize the eiect of current flowing through the. othenwinding of this relay. Consequently,

relay 129 ,does not respond to the transmission of any signals overthe loop 10|. Relay 129 does not operate` during idle periods during which relay 124 ,is maintained on its marking contact as shown in the drawings because the same curvrent flows through both windings of relay 129.

If,v however, the attendant for any reason Wishes to-interrupt the transmission of messages overv the system the attendant may operate the busy key 121.` Operation of rthe busy keyV connects groundto the upper conductor of loop 10| and interrupts the current ilowing over the lower conductor of this loop thus unbalancing relay 129. Atthis time no current will flow through the lefthand winding of relay 129 but current will ow through the right-hand winding of relay 129 and -causerelay 129 to operate and complete an obvious circuit for the operationof relay 123.

Operation of relay 123.during the time a messageis being transmittedvto the recording device ,completes a circuit for the operation of relay 1 I5. The operationof relay 123 also interrupts the operating or holding circuit of relay 1 I 6 which previously `extendedthrough the back contacts of relay 142.3. A` short interval of time later relay 1| 6 will release and complete aV circuit for the operation of relay 1|1. Relay 1|1 operates and completes a circuit for the operation of the .trouble lamp 1|9 andin addition connects `ground to the alarm circuit lead 190.

The operation of vrelay 1 I 1v also short-circuits resistance 128 which is connected in series with conductor. 8|4 extending through the operated cross bar contactsand lead 6I4 andthe winding `of themarginal relay 529 to ground'. Upon the .short-.circuiting of resistance 128 marginal relay 529-will operate and stop the operation of transmitter 528 in th'e manner described in the aboveidentiiiedBranson application and also indicate to the4 attendant at the central switching station thetransmitter from which the message is, being transmitted to recorder 125 at the time key 1.21 is operated. l

After the attendant atthe vcentral switching center hasdetermlned thesource 'of trouble or service requested by the 'outlying subscriber the 'circuits maybe restoredand transmission resumed as describedin the vabove-identiiied patent application ofBran'son et al. which forms a part of I vthepresent specification.

'Attheend of the message the director circuit 50 will respond to the end-of-message signal by 'advancing 'and interrupting the circuit of relay the operated cross 6I6 to ground. Inl

in its marking position so that it is unable to send any further signals over lines 10| to the receiving instrument 125.

Relay 1|2 in releasing also vremoves ground from lead 8H extending to the director circuit. The director circuit is advanced in response to the i removal of ground from lead8|| and 6|| and in 841 will then release and cause the cross bar switch contacts at the cross-point to open. The release of the h'old magnet 841 interrupts the locking circuit of busy relay 1H thus permitting this relay to release and connect lead 5|| to the winding of the hold magnet 841.

Y The release of magnet 841, the release of the cross bar switch contacts, as well as the release i of relays 1| I, 1|2-and 1|3, restore the rst channel of the multiple outlet circuit to its normal or idle condition.V When the next message-is directed to the multiple outlet circuits by the particular code combination assigned to' thesestations, circuits will function as described above and cause the message to be transmitted to the receiving machine 125. Y

The attendant or subscriber may operate the station busy key 121 associated with the recording device 125 at a time during which no signals are being recorded or received thereby. When key 121 is operated at these times relay 129 will operate, as described above, and complete a circuit for the operation of relay 123. The operation of relay 123 at this time completes a circuit for the operation of relay 1|| from battery through the left-hand winding of relay 1| l, the right-hand outer break contacts 0f relay 1|2 to ground through the operated contacts of relay 123. Relay 1|| in operating transfers lead 5|| from the winding of. hold magnet-841 to the winding of hold magnet 848.

It is also possible for the attendant at the central switching station to make the iirst channel of the multiple outlet circuit busy by operating busy key 1|8. The operation of this key again completes a circuit-.for the operation of relay 1| vfrom battery through the left-hand winding of relay 1H to ground through the right-hand operated contacts of key 1I8. As long as key 1|8 or 121 remains operated relay 1|| will remain operated and prevent messages from being `transmitted to recording instrument125.

Assume now for purposes of illustration that during the time relay 1|| is operated either due to the fact that messages are being transmitted to the recording instrument 125 or due to the operation of key 121 or due to the operation of key 1|8 a message is directed to the multiple outlet circuits. That is, it is preceded by an address code which designates the multiple outlet y circuits or station. In this case the lead 5|| will extend through the operated contacts of relay 1 I I'and the break contacts of relay 13| to battery through the winding of magnet 848 and the righthand break contacts of relay 134. Consequently, when the message addressed to the multiple outlet station arrives at the transmitting point of the transmitter 528 of director 50| or at the corresponding point of any of the otherdirectors the busy condition of the second channel .will be tested and magnet 848 operated during the time the selectory magnet 60| of. crossv bar switch is operated. Thereafterthemessage will be directed to the receiving instrument 146'in4thesame ass'aias manner as described above with reference to the transmission of messages to the receiving instr'ument 125.

As indicated above, the modification of the cirlcuit shown extending to recorder 145,is more f ated once for each code combination received by the recording device 145. In the modification shown extending to the recorder 145 the operation of-relay 132, which corresponds to the operation of relay 1|2 described above,.interrupts the operating circuit of relay 136. Relay 136, however, is a slow-release relay and requires an appreciable time before it releases and closes its contacts. Operation of relay 132 also extends a` circuit from battery through the winding of relay 135 and the right-hand outer operated contacts of relay 132 to the right-hand contact of universal contactsv 149. As described in the above-identified application of Branson et al. a short interval of time after relay 132 operates the circuits of the director will normally advance and cause the transmission of signals over conductor 6|2 and thence over conductor 832 through the operated cross bar switch contacts. will then be transmitted to the selector magnet 146 of the recorder 145 and cause the universal contact 149 to operate. During the normal operation of the system the universal contact 149 will be operated before relay 136 releases. The operation of these contacts completes a circuit for the operation of relay 135 and relay 135 in operating completes a circuit for maintaining itself operated from battery through its winding, the righthand outer operated contacts of relay 132 to ground through the left-hand operated contacts of relay 135.

The operation of relay 135 then extends a circuit from the winding of relay '|36 to the lefthand contacts of universal contacts 149. Consequently, lwhen the universal contacts 149 lare restored to their normal position at the end of each code combination a circuit will be'completed through the winding of relay '|36 thus tending to maintainy relay 1136 operated. Relay 136 is suflicientlyslow in releasing so that it will'be Amaintained operated by the closure of thelefthand contacts of the universal contacts during the transmission of signalsto the recording device 145. Consequently, transmission will proceed in the normal manner.

However, if for any reason the director Vcircuit does not transmit signals to the recording instrument vor the recording instrument does not respond to signals transmitted to it and cause the operation of universal contacts as described above before the release of relay 136, relay v136 will release and complete a circuit for the operation of relay 131 from battery through the winding of relay 131 and break contacts of relay 136 to ground through the right-hand inner operated contacts of relay 132.'v The operation of relay 131 completes a circuit for lighting the trouble lamp 139 and also connects ground to the lead extending to the alarm circuit. Inl addition, the operation* of relay 131 vshort-circuits resistance `148 These signals as eaizs connected in series with lead Bl 4 extendingto the director circuit and causes the operation .of relay 529 of the, director circuit which, asdescribed above and also in vthe above-identified application of Branson etal., causes the director cir-f. cuit to stop and light trouble lamps whereupon the trouble may be corrected by the attendant and the message transmitted to the proper station'.

The `operation of the busykey 141 duringthe time the message is being transmitted to the recording instrument 145 produces no eiect until after the transmission is completed. However,

after the message has been fully received and the circuit returned to its normalcondition or if the busy key is operated during the time the recorder 145 is idle a circuit will be completed for the operation of relay 13| from battery through the left-hand winding of relay 13| and the right-hand outer break contacts of relay 132 to ground through the operated contacts of the make-busy key 141. Relay 13| will thus be maintained operated as long. as the busykey 141 is operated. The' operation ofrelay '13| in. turn transfers the selecting lead extending-from the intercept key 552 to the break contacts of relay 15| associated` with the third channel ofthe multiple outlet circuit. Hence, no message Will be directed to the recording instrument 145 as long' as key 141 is operated.

The attendant at the central switching. station may operate the busy key ,138 which will cause the operation of relay 13| and thus prevent any.

messages from being directed to the recording instrument. 145. Y

If both the recording instruments 125 and 145 are busy receiving messages or one or both of the make-busy keys associated with them have been operated and another message is directed to the multiple outlet circuit lead 5|| extends,

through the operated contacts of relays 1|| and 13| through the break contacts of relays 15| and 154'to battery through the windingA of the hold magnet 849.` Consequently, this message will be directed over the third channel 104 to the recording instrument 155. The features of the invention incorporated in the circuits of the third channel operate in substantially the same manner as those described above with reference to the rst channel'excepting that no repeating relay is shown connected from the transmission channel 104 extending to the recorder 165.

l'f all of the recorders 125, 145 and 165 are busy relays 1I I, 13| and 15| Will likewise be operated. At this time lead 5| I will extend through the operated contacts of these relays to ground through the break contacts of the overilow key 110. Under these circumstances the director circuits, with the messages directed to the multiple outlet circuit in the transmitting and selecting positions, will wait until one or the other of the channels becomes idle at which time that channel will be seized and the message transmitted to the associated recording instrument. During the times of overload it may be sometimes esirable to provide an additionalnchannel to receive certain messages directed to the multiple outlet circuit. If it is desired the overflow key 110 may be operated at these times and extend lead 5|| through the operated contacts of relays 1H, 13| and 15| to lead 5l0 extending to the intercept circuit 503. Then if a message is directed to the multiple 'time all three of the recorders associated therewith are busy the succeeding message will be directed to the intercept circuit 503 where it may outlet circuit during thel individual tto each of said belaterV transmitted `to one of the recordersassociated with `the multiple outletcircuit. f l

vOf. courseifit isdesired to take the multiple outlet circuitcompletelyout ofserviceiit ispossible to operate the ransfer all `of the [messages preceded .by an address code` designating the multiple outlet/circuit to the intercept circuit. i.

VIt will alsobe apparent to those skilled in the arti-that. during nights and on Sundays and holidaysbusy, keysof one or more of .themultiple outlet4 recorders Amay be operated or the busy keysat the central stations associated with the respective channels may be operated whereupon all of the messages preceded by the address code designating the multiple outlet circuit or station will be automatically directed tothat machine orthose machines which do not have thek busyV keyi operated. In thismanner it is possible to haveamachine set aside `ata remote location for receiving urgent messages outside of. business hours.v Conversely, during business hours the machines at the location most suitablewduring business hours. ,It is of course possible to have machines at more than two locations when` de sirable. Y 4

What is claimed is: i l i 1. In* a telegraph system, a switching'station, means at said station for selectivelydirecting messages to telegraph lines inaccordance 'with address signals preceding: eachmessage, a. pluralityof receivingy printers, a telegraph channel printers extendingJ from said switching station, said switching apparatus for selecting any of said channels 7Vto individual `printers* which are idle in response to av common` address code and apparatus adjacent each of said printers .for conditioning said switching equipment to prevent rthe selection ofthe respective printer.

2. In a telegraph switching system in wh'ich messages are automatically directed to transmission channels in accordance with addressfcodes preceding the messages,.a plurality of transmission channels assigned a common addressl code, switchingapparatus vfor directing messages to said channelsindividually-in response to said common code and apparatus operative incident to the busy condition of one or more of Said plurality of channels for preassigning in apredetermined and preferential order others of said channels to which succeeding messages areindividually directed.

3. In a telegraph switching system in which messages are automatically directed to receiving printers in accordance with address codes preceding the messages, a plurality of receiving printers assigned a common address code, switching apparatus for directing messages to said printers individually in response to said common code,` apparatus controlled by the busy condition of the individual printers `of said pluralityof printers for determining the printer to which said messages are individually directed, and manually controlled means individual to at least certain of sai-d printers for preventing the direction of messages thereto by said switching equipment.

4. In a telegraph transmission system, a plurality of telegraph transmitting and receiving devices, switching apparatus responsive to directing codes preceding messages :for selectively directing the associated message to said .receiving devices, said switching apparatus including intercept key 552 and thus apparatus including 8 means for directing messages preceded by predetermined directing signals to any one ofV a group of receiving devices, and apparatus controlled by the busy condition of the-individual devices vof said igroup for preassigning one at a time and in apreferential order the receiving devices of said group` to which the next message will be directed.`

5. In a telegraph transmission system, a plurality tot; telegraph transmitting and receiving devices, switching apparatus responsive to directing codes preceding messages for selectively directing the associated message to said receiving devices, said switching apparatus including meansfor directing messages preceded by predetermined directing signals to any one of a group of receiving devices, apparatus controlled bythe busycondition of the individual devices of said group for determining the particular one of :said receiving devices of said group to which any given message is directed, and a manually controlled switching means adjacent one or more of thereceiving devices of said group for preventingthe transmission of messages thereto b-y saidlswitchin'g apparatus.

6. 1n a 'telegraph transmission system, a plurality of telegraph transmitting and receiving devices, switching apparatus responsive to directing codes preceding messages for selectively directing the associated 'message to said receiving devices, said A switching apparatus including means for ldirecting messages preceded by predetermined directing signals to groupof receiving devices, apparatus controlled ley-thev busy condition of the individuall devices of said group for determining the particular one of said receiving devices of said groupto which any given message is directed, and manually controlled switching apparatus adjacent one or more of. said receiving devices for making the associated receiving device test busy and to cause the transmission of messages to other receiving devices `of said group.

7. ,In` a telegraph system, a plurality of receiyingdevices assigned a common plurality. of codes, switching apparatus responsive to address codes preceding messages for automatically and selectively directing the associated message to receiving devices assigned the any one of a address of a` y code, apparatus respective address codes, a single leadassociated with said plurality of receiving devices assigned saidcommon address code, means included tin said! switching apparatus for selecting said common lead in response to saidvcommon address code, apparatus controlled by the busyY conditions of saidplurality of receiving devices assignedl a common address code for automatlcallyassociating'said lead with an idle one o-f said receiving devices, and means for initiating the connection of said idle receiving device to said switching apparatus over said single lead.

. 8'. 'In a telegraph system, a plurality of receiving devices assigned a common vaddress of a plurality of codes, switching apparatus responsive to address codes preceding messages for automatically and selectively directing the associated vmessage to receiving devices assigned the respective address codes, a single lead associated with said plurality of receiving devices assigned said common address code, means included in said switching apparatus for selecting said common lead in response tolsaid common address controlled by the busy `condition of a respective receivingdevice of said plurality of receiving devices assigned a `common address code for automatically associating said Vleadv with an idle one of said receiving devices.

9, In a telegraph system, a plurality of lreceiving devices assigned a common address code, switching apparatus responsive to address codes preceding messages for automatically and selectively directing the associated message to receiving devices assigned the respective address codes,

a single lead associated with said plurality of receiving devices assigned said common address code; means included in said switchingapparatus for selecting said common lead in response to said common address code, apparatus controlled by the busy condition of a respective receiving device of said plurality of receiving devices assigned a Acommon address coderfor automatically associating saidv lead with idle ones of said re- -ceivingdevices one at a time in a predetermined order, and means for initiating the connectiony of said idle receiving device to said switching apparatus over said single lead.l

DAVID E. BRANSON.

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