1、INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU TELEGRAPHY ALPHABETICAL TELEGRAPH TERMINAL EQUIPMENT S.16 (03193) CONNECTION TO THE TELEX NETWORK OF AN AUTOMATIC TERMINAL USING A V.24 DCUDTE INTERFACE ITU-T Recommendation S.16 (Previously “CCITT Recommenda
2、tion”) ITU-T RECMN*S.Lb 93 W 4862593 0540350 9bT W FOREWORD The IT Telecommunication Standardization Sector (IT-T) is a permanent organ of the International Telecom- munication Union. The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them
3、with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), which meets every four years, established the topics for study by the IT-T Study Groups which, in their turn, produce Recommendations on these topics. ITU-T Recommenda
4、tion S.16 was revised by the IT-T Study Group IX (1988-1993) and was approved by the WTSC (Helsinki, March 1-12, 1993). NOTES 1 As a consequence of a reform process within the International Telecommunication Union (ITU). the CCITT ceased to exist as of 28 February 1993. In its place, the IT Telecomm
5、unication Standardization Sector (ITU-T) was created as of 1 March 1993. Similarly, in this reform process, the CCIR and the IFRB have been replaced by the Radiocommunication Sector. In order not to delay publication of this Recommendation, no change has been made in the text to references containin
6、g the acronyms “CCITT, CCIR or IFRB” or their associated entities such as Plenary Assembly, Secretariat, etc. Future editions of this Recommendation will contain the proper terminology related to the new IT structure. 2 telecommunication administration and a recognized operating agency. In this Reco
7、mmendation, the expression “Administration” is used for conciseness to indicate both a O ITU 1994 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing
8、from the . ITU-T RECMN*S.lb 93 = 4862593 0590353 8Tb CONTENTS 1 General . 2 DCE/DTE interface 3 Signalling . Modes of operation - Timing diagrams . 4 Annex A - Automatic call by DTE . Annex B - Automatic call by DTE . Annex C - Teleprinter + DTE . Annex D - Answering by DTE . Annex E - Teleprinter a
9、nswering References . Recommendation S.16 (03/93) Page 1 1 2 4 5 6 8 9 10 11 i ITU-T RECMN*S.Lb 93 = 4862591 0590353 679 = Recommendation S.16 Circuit condition ON OFF CONNECTION TO THE TELEX NETWORK OF AN AUTOMATIC TERMINAL USING A V.24 DCEYDTE INTERFACE Voltage level Recornmendation Recommendation
10、 V.28 v.10 Logic level Signal Condition O 2 +3 v 2 +0,3 V Start A 1 2-3 v 5 -0,3 V stop Z (Former Recommendation V.ll, Mar dei Plata, 1968; amended at Geneva, 1980; Malaga-Torremolinos, I984 and at Helsinki, 1993) 1 General 1.1 This Recommendation describes a method of originating and answering call
11、s on the 50-baud telex network by means of an automatic terminal that uses interchange circuits defined in Recommendation V.24 I for the interface between the data terminai equipment (DTE) and the data circuit terminating equipment (DCE). In addition this Recommendation covers manual calling with au
12、tomatic switching to data processing or other off-line equipment and reply by teleprinter with automatic switching to a DTE. 1.2 A distinction is drawn between the two types of automatic calling in national telex networks - dial selection (using dial puises in accordance with Recommendation U.2 2) a
13、nd keyboard selection using 50-baud teleprinter signals International Telegraph Alphabet No. 2 (ITA2)I. 2 DCEIDTE interface 2.1 The interchange circuits used for the interface between the DCE and the DTE are defined in Recommen- dation V.24 i and comply with the technical specifications in either Re
14、commendation V.28 3 or Recommenda- tion V.10 4. Thus the correspondance between the voltages and the significant states is as shown in Table 1. TABLE 1K.16 Correspondence between significant states 2.2 The circuits used for automatic reply (see Figures 1 and 2) are CT 102, 103, 104, 107, 10812, 125
15、and 132. 2.3 The circuits used for automatic calling with dial selection (see Figure I) are those listed in 2.2 supplemented by CT 202, 206, 207, 208, 209, 210, 21 1 and 213. The 200-series circuits are not connected directly to the DCE but to an automatic calling equipment (ACE) built into the DCE,
16、 which explains the presence of CT 202 to 213. These circuits may be used by a single DTE connected to a single DCEYACE. Recommendation S.16 (OY93) 1 ITU-T RECMN+S.Lb 93 m 48b2591 0590354 505 m 2.4 supplemented by CT 202, which is connected directly from the DTE to the DCE. The circuits used for aut
17、omatic calling with keyboard selection (see Figure 2) are those listed in 2.2 2.5 Where a DTE has access through a DCE to several telex lines of the public network, the DCE shall select for each call attempt one telex line and one only (which need not be the same one as for the preceding attempt) an
18、d in no case is the DCE allowed to present the same call simultaneously on more than one telex line. The calling and answering procedure and signalling between DTE and DCE are identical, after connection to a telex line, with those that are used when a DCE is connected to one telex line only, which
19、are described in the diagrams below. 2.6 If several DTE are connected to the telex network through the same DCE, each DTE shall make its call attempts to the network using the procedure described in this Recommendation. On the other hand, when it is in the answering position for a call coming from t
20、he telex network, the DCE is responsible for handling the calls intended for the DTE concerned using the procedure described in Recommendation F.71 5 on the interconnection of the telex network with private teleprinter networks. As soon as the DCE has selected the DTE concerned, the answering signal
21、 to the call at the DTEJDCE interface and the signalling on the telex line will be identical to those used in the case of a single DTE as described in the diagrams below. 2.7 In the timing diagrams below (see Annexes A to E), the ON condition in the interchange circuits is denoted by a solid line an
22、d the OFF condition by the absence of a line. For CT 103 and 104,* means that the DCE connects them to line and 0 means that the DCE disconnects them from the line. 3 Signalling 3.1 These interfaces may be used with the three following types of telex signalling: - type A (keyboard selection); - type
23、 B (keyboard selection); - type B (dial selection). 3.2 The signalling between the DCE and the national telex exchange is not standardized by the CCITT. The signalling protocol shown in the timing diagrams (see Annexes A to E) are only examples to indicate the interdependence between the signalling
24、on the subscriber lines and the status of the interchange circuits. 3.3 Automatic calling with type B signalling and dial selection is described in Annex A. Automatic calling with either type A or B signalling and keyboard selection is described in Annex B. The other annexes are common to all types
25、of signalling. 3.4 The SSSS sequence (four times combination No. 19 in ITA2), if required, is transmitted either after the exchange of answer-back codes and through-connection, if network-controlled, or, otherwise, after reception of the call-connected signal. The purpose of the SSSS sequence is to
26、indicate that the exchange of “data” is about to start and that no further “telex” signals that might disturb the exchange of data should be transmitted or interpreted. It enables the equipment that is required for the exchange of data, which may then commence after a 500 ms delay, as specified in R
27、ecommendation S.15. This sequence may be omitted where an exchange of messages in ITA2 is to take place, providing disabling of the answer-back function is not considered necessary. 3.5 the DTE. In the event of reply by teleprinter, the last character of the SSSS sequence initiates automatic switchi
28、ng to 3.6 operation. A special data signal may be sent by the DTE to cause the distant terminal to return to the telex mode of 3.7 interpret at least the following service signais: OCC, ABS, NA, NP, NC, NCH, DER. The DTE must comply with Recommendation U.40 6 concerning ineffective attempts. It must
29、 be able to 2 Recommendation S.16 (M3) ITU-T RECflN*wS.lb 93 4862593 0590355 441 r L r CT2C i Digit signal (22) I CT 209 I Digit signai (23 ) I CT102 i signai ground Automatic calling cT103 : Data (transmitted) CT104 i Data (receiwd) I I L r CT 211 Digit present I CT108R ; Data temiinal ready CT 107
30、 Data set ready r equipment (ACE) I T CT 125 I Calling indicator CTlZ I Return to nondata mode CT 2C ! Call request I 7 L I I I I I CT 206 I Digit signal (20) L CT207 i Digit signal (21 ) CT210 i Present nexi digit CT 213 ! Pwer indication 1 Control Urit Data circuit termmating equipment (DCE) FIGUR
31、E VS.16 Interface for automatic calling (dial selection) FIGURE 26.16 Interface for automatic calling (keyboard selection) NOTES to Figures 1B.16 and US.16 I is ready to receive the selection information. 2 therefore transmitted serially by the DTE on CT 103. 3 clearing of a call. 4 automatic callin
32、g, the simultaneous ON condition of CT 125 and 202 informs the DTE that it must abandon its call attempt to permit acceptance of the incoming call. 5 designated CT 108/1, would fulfil the functions of CT 108/2 and 202. CT 106 and 109, which are unnecessary for telegraph operation, have been suppress
33、ed. CT 107 indicates that the DCE With keyboard selection, the selection signais (start-stop iTA2) are of the same type as the “data” signals. They are CT 10812, which is mainly used to indicate that the DTE is ready to receive a call, also serves, when OFF, to initiate CT 203 is not essential since
34、 the proceed-to-select signal is indicated by CT 107 and, in the event of call collision in CT 202 may also be suppressed by assigning the calling function to CT i 08/2. The latter, which should then be Recommendation S.16 (03/93) 3 ITU-T RECMN*S-Lh 93 = 48b2591 0590356 388 4 Modes of operation - Ti
35、ming diagrams 4.1 The various modes of operation and equipment configurations are illustrated in the annexes below as follows: Annex Subject A Automatic call by DTE B Automatic call by DTE C (dial selection) (keyboard selection) Teleprinter + DTE (manual call with manual or automatic switching to DT
36、E) D Answering by DTE E Teleprinter answering (with automatic switching to DE) Signalling (dial selection) Types A and B (key board) All types Type 3 All types All types 4.2 The following abbreviations and signs are used in Annexes A to E: Ah3 Telex answer-back code DCE Data circuit terminating equi
37、pment DTE Data terminal equipment ms Millisecond SSSS S Second WRU * 0 - Transfer sequence (see 3.4 above) “Who are you? signal (combinations Nos. 30 and 4) CT 103 and 104 connected to line CT 103 and 104 disconnected from line A broken line indicates that the circuit may be either ON or OFF 4 Recom
38、mendation S.16 (03/93) Annex A Automatic call by DTE (Dial selection) (This annex forms an integral part of this Recommendation) Call phases Free line Call from DTE DCE sends call to nehnrork DCE receives call-confirmation and proceed-to-select siyal DCE switches CT 21 O to ON CT 206,207,208 and 209
39、 DTE switches CT 21 1 to ON DCE sends first digit to network DCE switches CT 210 to OFF DTE switches CT 21 1 to OFF DCE switches CT 21 O to ON DTE presents the end-of-number (EON) signals DTE swlches CT 21 1 to ON DCE switches CT 21 O to OFF and holds until call is cleared DTE switches CT 21 1 to OF
40、F DCE receives the call-connected signai, switches CT 107 to ON and connects CT 1 O3 and CT 104 through to line If no answer-back signal is received after 3 s, DTE transmits WRU signal DTE presents the first digit on .- DTE receives ma) DTE sends ssss sequenceb) Exchange of data may start after 500
41、ms If calling DTE wishes to revert to the normal telex, mode. the DTE sends a special data signal. Where a) the AB simulator is located in the DTE, the sirnulator is reenabled, b) the A/B simulator is located in the DCE, DTE switcha CE 132 ON. Normal telex transmission may start after 2 5 Clearing f
42、rom calling DTE) DCE receives clear-confirmation Free line DTE receives clear request from called DTE) DCE returns clear-confirmation Free line Subscriber lines Interchange circuits L X ,I I II I his must not respond to the WRU signal. a) If an A/B simulator is provided in the DCE, the b, This SSSS
43、sequence is recognized by: a) the DTE, il the A/B simulator is located in the DTE; b) the DCE, il the A/B simulator is located in the DCE. In either case, the NB simulator is disabled. If the NB simulator is located in the DCE and is disabled, it is re-enabled. T0900990-94/d Recommendation S.16 (03/
44、93) 5 ITU-T RECflN*S.Lb 93 4862.593 0590358 150 = Annex B Automatic call by DTE (Keyboard selection) (This annex forms an integral part of this Recommendation) Call phases Free line Call from DTE, DCE sends call to network DCE receivec callconfirmaton and (where appropriate) proc b) the DCE, if the
45、A/B simulator is located in the DCE. in either case, the AB simulator is disabled. r I I j Q I b, If the AA3 simulator is located in the DCE and is disabled, it is re-enabled. Toso 101 &94/& Recommendation S.16 (03D3) 7 Annex C Subscriber lines $8 nM Lm Teleprinter + DTE (Manual call with manual or
46、automatic switching to DTE) (This annex forms an integral part of this Recommendation) Interchange circuits 103 104 107 10&2 125 132 202 Call phases Free line The operator calls the telexcentre DCE receivec call-confination signal The operator sends selection signals and sets up call in the usual wa
47、y The telex terminal equipment receives called temiinalS A/B The operator sends CCCC squence Manual or automatic switching to DTE Exchange of data may start after 500 ms Clearing from calling DTE DCE receivec clear-confirmation Free line Calling telex operator clears: Manual switching to the telex l
48、ine Operator clears DCE receiws clear-confirmation Free line Clear request from called DTE DCE sends back clear-confirmation Free line 1 F IMmc u 8 Recommendation S.16 (03/93) i Subscriber lines Annex D Interchange circuits Answering by DTE (This annex forms an integral part of this Recommendation)
49、Call phases Free line Incoming call DCE returns call-confirmation DTE receites WRU signal DTE sends AB If AiB ezhange is initiated bythe network, DTE receives callklg terminals A/B DTE receiws SSSS sequence Exchange of daba may start after 500 ms Clearing from calling DTE DCE raurns clearconfirmation Free line Called DTE clears the call DCE receivec clear-confirmation Free line When DTE is not ready to receiw a call: %e line ncoming call ICE returns call-confirmation f CT 108i2 is not switched to ON in the 2 s following the switching CT 125 to ON, DCE cl
