1、NEMA Standards PublicationNational Electrical Manufacturers AssociationANSI C12.21-2006Protocol Specification for Telephone Modem CommunicationANSI C12.21-2006 Revision of C12.21-1999 American National Standard Protocol Specification For Telephone Modem Communication Secretariat: National Electrical
2、 Manufacturers Association Approved May 2, 2006 American National Standards Institute, Inc. ANSI C12.21-2006 NOTICE AND DISCLAIMER The information in this publication was considered technically sound by the consensus of persons engaged in the development and approval of the document at the time it w
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17、withdraw this standard. Purchasers of American National Standards may receive current information on all standards by calling or writing the American National Standards Institute. Published by National Electrical Manufacturers Association 1300 North 17th Street, Rosslyn, VA 22209 Copyright 2006 by N
18、ational Electrical Manufacturers Association All rights reserved including translation into other languages, reserved under the Universal Copyright Convention, the Berne Convention for the Protection of Literary and Artistic Works, and the International and Pan American Copyright Conventions. No par
19、t of this publication may be reproduced in any form, in an electronic retrieval system or otherwise, without the prior written permission of the publisher. Printed in the United States of America ANSI C12.21-2006 ii This page intentionally left blank.ANSI C12.21-2006 iii Contents Page 1 Scope1 2 Ref
20、erences .1 3 Definitions and Syntax1 3.1 Definitions.1 3.1.1 C12.21 Client1 3.1.2 C12.21 Device2 3.1.3 Table.2 3.2 Document Syntax .2 4 Protocol Details 2 4.1 Order of Transmission2 4.2 Layer 7 - Application Layer.3 4.2.1 Data Structure 3 4.2.2 Protocol Specification for Electric Metering .3 4.2.2.1
21、 Request Codes .3 4.2.2.2 Response Codes.4 4.2.2.3 Identification Service .5 4.2.2.4 Read Service.9 4.2.2.5 Write Service.9 4.2.2.6 Logon Service .9 4.2.2.7 Security Service 9 4.2.2.8 Logoff Service .9 4.2.2.9 Authenticate Service .10 4.2.2.10 Negotiate Service11 4.2.2.11 Wait Service 11 4.2.2.12 Te
22、rminate Service .11 4.2.2.13 Timing Setup Service 11 4.2.2.14 Disconnect Service .12 4.3 Layer 6 - Presentation Layer 12 4.4 Layer 5 - Session Layer12 4.5 Layer 4 - Transport Layer.12 4.6 Layer 3 - Network Layer .12 4.7 Layer 2 - Data Link Layer .13 4.7.1 Basic Data Information.13 4.7.1.1 Fixed Sett
23、ings13 4.7.1.2 Variable Settings .13 4.7.2 Packet Definition 13 4.7.3 Duplicate Packets.15 4.7.4 CRC Selection15 4.7.5 Acknowledgment15 4.7.6 Retransmission.16 4.7.7 Time-out .16 4.7.7.1 Channel Traffic Time-out.16 4.7.7.2 Inter-Character Time-out.16 4.7.7.3 Response Time-out.16 4.7.8 Turn-around De
24、lay .16 4.7.9 Collision16 4.8 Layer 1 - Physical Layer.16 5 Compliance.16 Annex A - Communication Example (Layer 7 and Layer 2) .18 Annex B - Packet Transmission Example.20 Annex C - Service Sequence State Control22 Annex D - Modifications and Extensions to C12.19- 1997 .24 ANSI C12.21-2006 iv D.1 R
25、DATE Type.25 D.2 Table 03 ED_MODE STATUS Table .27 D.3 Table 07 - Procedure initiate Table 30 D.4 Decade 90: Telephone Control Tables.31 D.5 History and Event Log Codes.48 D.6 Default Sets for Decade Tables .49 D.7 Indices for Partial Table Access .50 Annex E - CRC Examples.53 E.1 Trace.53 E.2 C Cod
26、e Example 54 Annex F - Error Handling 55 Annex G - Data Encryption Standard57 G.1 Usage .57 G.2 Legal Issues57 G.3 Implementation .58 G.4 Code Example 61 G.5 Trace Example63 Annex H - I Command Operational Description65 Annex I - Compatibility 66 I.1 Backward Compatibility With Previous Versions of
27、the Standard66 I.2 Forward Compatibility With Next Versions of the Standard .66 Annex J - Historical Background.68 J.1 Foreword of C12.21-1999.68 ANSI C12.21-2006 v Foreword (This Foreword is not part of American National Standard C12.21-2006.) This American National Standard provides an open-platfo
28、rm communications protocol for two-way communication with a metering device via a telephone modem. The protocol is written to conform to the OSI seven-layer stack. Long-time readers of ANSI C12.21 will discover many editing changes to this version of the Standard. The Working Group chose to improve
29、the clarity of the text as an aid to the reader while retaining the normative elements in the manner of previous publications. The 2005 revision of this Standard was considered in the context of the so-called “protocol suite” of ANSI standards: C12.18, C12.19, C12.21 and C12.22 (draft). Changes made
30、 were included only after assuring that existing devices implementing C12.21 would continue to remain compatible with the 2005 revision. It is expected that the Logoff Service will become mandatory in the next revision of this Standard. Implementers are strongly encouraged to support this service to
31、 comply with this change. Suggestions for improvement to this Standard are welcome. They should be sent to: National Electrical Manufacturers Association Vice President of Engineering 1300 North 17th Street Suite 1752 Rosslyn, VA 22209 This Standard was processed and approved for submittal to ANSI b
32、y Accredited Standards Committee for Electricity Metering C12. At the time the committee approved this Standard, the C12 Committee had the following members: Tom Nelson, Chairman Paul Orr, Secretary Michael Anderson Ed Beroset Ron Breschini Curt Crittenden David Ellis Cruz Gomez Bob Hughes Lawrence
33、Kotewa Francis Marta John McEvoy Herman Millican James Mining Avygdor Moise Tim Morgan Roy Moxley D. Young Nguyen Lauren Pananen Aaron Snyder Richard Tucker Scott Weikel ANSI C12.21-2006 vi Working Group 4 of Subcommittee 17 that revised this Standard consisted of: Aaron Snyder, Chairman Peter Marti
34、n, Vice Chairman Norbert Balko, Editor Michael Anderson Ed Beroset Martin Burns Lawrence Kotewa Robert McMichael Avygdor Moise Vuong Nguyen Terry Penn Bin Qiu Richard Tucker Michel Veillette Virginia Zinkowski 1 AMERICAN NATIONAL STANDARD ANSI C12.21-2006 Protocol Specification For Telephone Modem C
35、ommunication 1 Scope This Standard details the criteria required for communications between a C12.21 Device and a C12.21 Client via a modem connected to the switched telephone network. The C12.21 Client could be a laptop or portable computer, a master station system or some other electronic communic
36、ations device. This Standard does not specify the implementation requirements of the telephone switched network to the modem, nor does it include definitions for the establishment of the communication channel. This document provides details for an implementation of the OSI 7-layer model. The protoco
37、l specified in this Standard was designed to transport data in Table format. The Table definitions are in ANSI C12.19, and Annex D of this document. This Standard specifies the differences between ANSI C12.18-2005, Protocol Specification for ANSI Type 2 Optical Port and ANSI C12.19-1997, Utility Ind
38、ustry End Device Data Tables, and those features and services required to describe a protocol specification for Telephone Modem Communications. 2 References ANSI C12.18, Protocol Specification for ANSI Type 2 Optical Port ANSI C12.19, Utility Industry End Device Data Tables ANSI INCITS 92-1981 (R200
39、3), Data Encryption Algorithm ISO/IEC 7498-1 (1994), Information Technology - Open Systems Interconnection - Basic Reference Model: The Basic Model ISO/IEC 8825-1 (2002), Information Technology - ASN.1 Encoding Rules: Specification Of Basic Encoding Rules (BER), Canonical Encoding Rules (CER) And Di
40、stinguished Encoding Rules (DER) ISO/IEC 13239 (2002), Information Technology - Telecommunications And Information Exchange Between Systems - High-Level Data Link Control (HDLC) Procedures 3 Definitions and Syntax 3.1 Definitions For the purposes of this Standard, the following definitions are made.
41、 3.1.1 C12.21 Client An electronic communication apparatus that connects to a C12.21 Device via a modem and implements communication according to the protocol specification of this Standard. This was implicitly defined in previous versions as “utility host”. ANSI C12.21-2006 2 3.1.2 C12.21 Device An
42、 electronic communication apparatus (e.g., a meter plus an internal or external modem) that implements communication according to the protocol specification of this Standard. This was implicitly defined in previous versions as “meter”. 3.1.3 Table Functionally related data elements, grouped together
43、 into a single data structure for transport as defined by ANSI C12.19. 3.2 Document Syntax Document syntax is identical to that of ANSI C12.18. 4 Protocol Details Following the guidelines established by the OSI seven-layer model, the protocol described in this Standard provides three (3) functions:
44、1) Establishment and modification of the communication channel 2) The transport of information to and from the C12.21 Device 3) Orderly closure of the communication channel when communications are complete Three (3) layers are used to provide these communication capabilities, the Physical, Data Link
45、 and Application layers. This Standard does not specify the implementation requirements of the telephone switched network to the modem, nor does it include definitions for the establishment of the communication channel. The communication channel is considered available once the telephone connection
46、has been successfully established and modems have synchronized. The PSEM Identification Service is required to establish the protocol version and revision in use. Certain communication parameters may be modified through the use of the PSEM Negotiate and Timing Setup services in the Application Layer
47、. These services are optional, and if not implemented in the C12.21 Device or not used during actual communications, the communication channel parameters will remain at the default settings specified by this Standard. Implementers are strongly encouraged to implement these optional Application Layer
48、 services. Once the data link is established, the Application Layer provides: Logon, Security and Logoff services for session activation, access control and deactivation Read Service and Write Service for issuing data transmission requests Authenticate Service for two way authentication with playbac
49、k rejection Terminate Service for returning to the Base State Disconnect Service for shutdown of the communication channel A response structure that provides information regarding the success or failure of the service requests. An example of a typical communications session would consist of the following services with appropriate responses, in the order listed: Identification, Negotiate, Logon, Authenticate, Security, Reads or Writes, Logoff and Disconnect. Note that this brief example does not detail the packet structure or other aspects of the protocol. A more detailed exampl
