1、INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU TERMINALS FOR TELEMATIC SERVICES T.31 (08/95) ASYNCHRONOUS FACSIMILE DCE CONTROL - SERVICE CLASS 1 ITU-T Recommendation T.31 (Previously “CCITT Recommendation”) COPYRIGHT International Telecommunications Unio
2、n/ITU TelecommunicationsLicensed by Information Handling Services ITU-T RECMN*T.31 95 4862591 Ob02852 887 FOREWORD The IT-T (Telecommunication Standardization Sector) is a permanent organ of the International Telecommunication Union (IT). The ITU-T is responsible for studying technical, operating an
3、d tariff questions and issuing Recommen- dations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn,
4、 produce Recommendations on these topics. The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSC I l Resolution No. 1 (Helsinki, March 1-12, 1993). ITLJ-T Recommendation T.31 was prepared by ITLJ-T Study Group 8 (1993-1996) and was approved under th
5、e WTSC Resolution No. 1 procedure on the 11th of August 1995. NOTE In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. O IT 1995 All rights reserved. No part of this publication may be
6、reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the IT. COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesCONTENTS Introduction and sco
7、pe . 1.1 Facsimile terminals . 1.2 Facsimile DCE 1.3 Scope 1.4 Overview Normative references . Definitions Abbreviations . Facsimile DTE-DCE interchange circuits . 5.1 DTE-DCE communication link data rates . 5.2 Asynchronous to synchronous conversion . 5.3 How control 5.4 Serial data interchange cir
8、cuits . Autodialler services 6.1 Command syntax 6.2 Command execution . 6.3 Response syntax 6.4 Capabilities identification and control 6.6 Call origination . 6.7 Call termination 6.8 Result codes . 6.9 Serial port flow control . 6.10 6.11 Transparent data commands . Facsimile Service Class 1 . 7.1
9、Connection establishment . 7.2 Waiting and silence detection . 7.3 Data transfer 7.4 HDLC framing. transparency, and error detection . 7.5 Facsimile carrier error message response . Service Class 1 commands and responses 8.2 Capabilities identification and control 8.3 Service Class 1 action commands
10、 . 8.4 Service Class 1 result codes 8.5 Service Class 1 parameters . 6.5 Call answering Serial port speed control . 8.1 Command summary Annex A . Interworking with existing facsimile DTE Appendix I . Service Class 1 example sessions . Calling sequence, transmitting a single page facsimile Appendix I
11、I - Recommendations for DTE compatibility Clarification of switching transmit modulation schemes 1.1 1.2 Answering and receiving a single page facsimile . Clarification of switching from HDLC reception to transmission 11.1 11.2 Recommendation T.31 (OW95) Page 1 1 1 1 1 2 3 3 3 4 4 4 4 5 5 6 6 6 7 7
12、7 7 8 8 8 9 9 10 10 10 10 10 11 12 13 15 16 18 20 20 21 23 23 23 1 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesSUMMARY A Group 3 Facsimile Terminal may include a DTE and a Facsimile DCE. This Recommendation describes a Facsimile DCE
13、 that includes physical and data layer functions. The corresponding DTE must implement the T.30 session protocol, and any necessary higher layer functions, such as Recommendations T.4, T.6 or T.434. KEYWORDS Class 1; DCE; Group 3 Facsimile; Modem; Programmable Communications Interface. 11 Recommenda
14、tion T.31 (08D5) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling Services ITU-T RECMN*T=31 95 E 48b259L Ob02855 596 Recommendation T.31 ASYNCHRONOUS FACSIMILE DCE CONTROL - SERVICE CLASS 1 (Geneva, 1995) 1 Introduction and scope 1.1 Facsimile t
15、erminals Group 3 facsimile machines were developed for sending digitized documents over the General Switched Telephone Network (GSTN). These facsimile terminals are now in widespread use around the world. The operation of Group 3 facsimile terminals has been standardized in Recommendations T.4, T.6
16、and T.30. 1.2 Facsimile DCE There are two types of adapters which allow Data Terminal Equipment TE) to communicate as Group 3 facsimile terminals. Some of these adapters are installed inside the DTE, on the processor bus; these are called “FAX boards”. Others are configured as an external “facsimile
17、 DCE, connected to the DTE by a standard serial port (e.g. Recommendation V.24), using serial data interchange, as definedin Recommendation V.4. 1.3 Scope This Recommendation contains protocols for use between a DTE and a Facsimile DCE. It includes automatic calling and answering. This Recommendatio
18、n defines the commands that the DTE may issue to configure and control the DCE, and the responses the facsimile DCE may issue to those commands. This Recommendation is useful for intelligent DTEs and DTE software, facsimile DCEs, and facsimile terminals with digital connection to DTEs. This Recommen
19、dation assumes that the DTE and DCE are connected via serial asynchronous connection using V.24 circuits. However, the protocols defined may be implemented in any environment that provide a character serial bidirectional data stream, including processor bus attached “fax boards”, local area networks
20、, Small Computer Systems Interface (IS0 9316), IEEE 1284 parallel ports, etc. The adaptation of the protocols and procedures to these alternative communication schemes is beyond the scope of this Recommendation. 1.4 Overview A system including a DTE and a facsimile DCE partitions Group 3 facsimile f
21、unctions between the two devices. There are several levels in the communications path where a functional partition can be made. This Recommendation describes protocols for use at one of those levels, Service Class 1. Each level is described as a “Service Class” based on the functions performed by th
22、e DCE. 1.4.1 Service Class 1 Clause 7 describes a set of services at the physical and data link layers: waiting, signalling, and HDLC data formatting. T.30 session management and T.4 image data handling are done by the DTE. 1.4.2 Service Class 2 Recommendation T.32, Asynchronous Facsimile DCE Contro
23、l, Service Class 2, describes a facsimile DCE which provides a set of services described by Recommendation T.30. The facsimile DCE makes and terminates calls, manages the communication session, and transports image data. The DTE prepares and interprets image data in compressed form, as described in
24、Recommendation T.4. Recommendation T.31 (OW95) 1 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling Services ITU-T RECMNUT.32 95 4862592 Ob02856 422 W 2 Normative references The following ITU-T Recommendations, and other references contain provisi
25、ons which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; all users of this Recommendation are therefore encouraged to investigate the possi
26、bility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid IT-T Recommendations is regularly published. - ITU-T Recommendation T.4 (1993), Standardization of Group 3 facsimile apparatus for document transmission. - IT-T Recommen
27、dation T.30 (1993), Procedures for document facsimile transmission in the general switched telephone network. - ITU-T Recommendation T.32 (1995), Asynchronous facsimile DCE control - Service Class 2. - CCITT Recommendation T.50 (1992), International Reference Alphabet (IRA) (formerly Intemational Al
28、phabet No. 5 or IA5) - Information technology - 7-bit coded character set for information interchange. - CCIT Recommendation V.4 (1988), General structure of signals of Intemational Alphabet No. 5 code for character oriented data transmission over public telephone networks. - ITU-T Recommendation V.
29、8 (1994), Procedures for starting and ending sessions of data transmission over the general switched telephone network. - CCIT Recommendation V.17 (1991), A 2-wire modem for facsimile applications with rates up to 14400 bids. - CCIT Recommendation V.21 (1988), 300 bits per second duplex modem standa
30、rdized for use in the general switched telephone network. - ITU-T Recommendation V.24 (1993), List of definitions for interchange circuits between data terminal equipment (DTE) and data circuit-terminating equipment (DCE). - CCIIT Recommendation V.25 (1988), Automatic answering equipment ador parall
31、el automatic calling equipment on the general switched telephone network including procedures for disabling of echo control devices for both manually and automatically established calls. - ITU-T Recommendation V.25 ter (1995), Serial asynchronous automatic dialling and control. - CCIT Recommendation
32、 V.27 ter (1988), 4800/2400 bits per second modem Standardized for use in the general switched telephone network. - CCIIT Recommendation V.29 (1988), 9600 bits per second modem standardized for use on point-to-point 4-wire leased telephone-type circuits. - CCIT Recommendation V.33 (1988), 14400 bits
33、 per second modem standardized for use on point-to-point 4-wire leased telephone-type circuits. - ITU-T Recommendation V.34 (1994), Amodem operating at data signalling rates of up to 28800 bids for use on the general switched telephone network and on leased point-to-point 2-wire telephone-type circu
34、its. - IS0 21 1 1: 1985, Data communication - Basic mode control procedures - Code independent information transfer. 2 Recommendation T.31 (08/95) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling Services3 Definitions For the purposes of this Re
35、commendation, the following definitions apply: 3.1 data to operate a DCE or facsimile DCE. In practice, these are computers of any size. DTE, Data Terminai Equipment: A DTE is any terminal or computer capable of providing commands and 3.2 A DCE is any device that connects a DTE to a communications n
36、etwork. This Recommendation focuses on DCEs which connect to the General Switched Telephone Network (GSTN). This class of DCEs includes DCEs compatible with the V-Series modem Recommendations and facsimile DCEs described below. DCE, Data Circuit Terminating Equipment: 3.3 DTE and the GSTN. A Class 1
37、 facsimile DCE includes the following functions: Facsimile DCE: A facsimile DCE is a device which provides facsimile communication facilities between a 0 control functions; 0 interchange circuits to the DTE; 0 HDLC data link layer functions; 0 V-Series signal converters; 0 autodialler functions; GST
38、N interface. 3.4 by the facsimile DCE. The specific implementation of these functions is beyond the scope of this Recommendation. Facsimile DTE: A facsimile DTE must provide those Group 3 facsimile functions and services not provided 4 Abbreviations For the purposes of this Recommendation, the follo
39、wing abbreviations are used: CCK International Telegraph and Telephone Consultative Committee IEEE Institute of Electrical and Electronics Engineers IRA International Reference Alphabet (Recommendation T.50) IS0 International Organization for Standardization IT-T International Telecommunication Unio
40、n - Telecommunication Standardization XON IRA DC1 character, used to enable data flow on the opposite circuit XOFF IRA DC3 character, used to disable data flow on the opposite circuit 5 Facsimile DTE-DCE interchange circuits A facsimile DCE described by this Recommendation uses an asynchronous seria
41、l connection between the DTE and the DCE. Serial data is formatted in 10 bit character frames, including a start bit, 8 data bits, no parity and 1 stop bit (see Recommendation V.4). Use of this protocol on other DTE-DCE interfaces is beyond the scope of this Recommendation. Recommendation T.31 (OW95
42、) 3 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling Services5.1 DTE-DCE communication link data rates 102 103 The DTE-facsimile DCE communications link shall provide full duplex character data at rates fast enough to accommodate the transfer of
43、 synchronous T.30 Phase C data. A data rate greater than or equal to 18000 bitis (e.g. 19200 bitfs) is the minimum rate needed to support 14400 bitfs V.17 Phase C data. With flow control, it is not necessary, and not recommended, to change the DTE-DCE communications link data rate during facsimile o
44、peration. Mechanisms to set the DTE-DCE serial rate are described in 6.10 and 6.2.10N.25 ter (IPR parameter). Signal ground Transmitted data 5.2 Asynchronous to synchronous conversion 104 Group 3 data communication is bit-synchronous. The DCE must delete, start and stop elements from these character
45、s before transmission and add them to received octets. Bit sequencing is maintained between the DTE-DCE interface and the DCE-remote station interface, as specified in Recommendations T.4 and T.30. Received data 5.3 Flow control Flow control is necessary to match the DTE-DCE data rate to the line si
46、gnalling rate and to the requirements of Group 3 data transmission. (For example, provision must be made for minimum scan line times.) Provision of in-band unidirectional DClDC3 (T.50 1/1 and 1/3) flow control is mandatory; flow control using V.24 circuits 106 and 133 is optional. This Recommendatio
47、n specifies a mandatory command to configure DCE flow control, the +IFC command from 6.2.12N.25 ter. The response times of the DCE to indication of a DTE not-ready condition and of the DTE to indication of a DCE not- ready condition are for further study. These times should be kept as short as pract
48、ical. DCEs should accommodate latency in the DTE recognition of the DCE not-ready indication by accepting several characters on Circuit 103 after the indication is given. NOTE - A facsimile DCE may provide additional data buffering beyond the needs of flow control. 5.4 Serial data interchange circui
49、ts 5.4.1 Mandatory circuits The required circuits are shown in Table 1: TABLE lK.31 Mandatory serial data interchange circuits I V.24 circuit I Description I 4 Recommendation T.31 (OW95) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling Services5.4.2 Optional circuits The optional circuits are shown in Table 2: TABLE uT.31 I 133 I 1 o5 Ready for receiving Request to send Ready for sending Data terminai ready Data channel received line signai detector Calling indicator Provision of additional circuits is optio
