NEMA Publishes Specs for ANSI Optical Port, Telephone Modem Communication - ANSI C12.18, ANSI C12.21
March 8, 2007 // Published as a news service by IHS
ANSI C12.18-2006 details the criteria required for communications between a C12.18 device and a C12.18 client via an optical port. The C12.18 client may be a handheld reader, a portable computer, a master station system or some other electronic communications device.
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This standard establishes protocol specifications and provides an open-platform communications protocol for two-way communication with a metering device through an ANSI Type 2 optical port.
It also covers compliance, backward and forward compatibility, the use of reserved fields, the identification service, packet size and the toggle bit. Some alignment with the draft ANSI C12.22 standard was performed to meet the goal of producing a coherent suite of protocol standards.
ANSI C12.21-2006 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 communications 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 standard establishes protocol specification for telephone modem communication and provides an open-platform communications protocol for two-way communication with a metering device via a telephone modem. It is expected that the logoff service will become mandatory in the next revision of the standard. Implementers are strongly encouraged to support this service.
Both publications clarify text while retaining the normative elements of previous publications and conform to the OSI seven-layer stack. Protocols specified in these standards were designed to transport data in table format. The table definitions are in ANSI C12.19-1997 - Utility Industry End Device Data Tables.
Revisions were considered in the context of the so-called "protocol suite" of ANSI standards: C12.18, C12.19, C12.21 and C12.22 (draft). Changes were included only after ensuring that existing devices would continue to remain compatible with the 2005 revision.