scope:

This standard presents hardware and protocol specifications for local systems, while specifications for a remote system falls within the scope of another document. This standard deals with direct local systems, in which the hand-held unit (HHU) is connected to one tariff device only at time. Connection can be permanent or disconnectable through an electrical or optical coupling. The protocol took as its basis the basic reference model for communication between open systems (OSI). The protocol permits the reading and programming of tariff devices. It has been designed to be particularly suitable for the environment of electricity metering, especially as regards electrical isolation, and software security. While the protocol is well-defined, its use and application is left to the user. This standard prescribes the hardware and software preconditions which permit an exchange of data between a tariff device and HHU. The connection to the HHU may be either permanent or disconnectable. Electrical as well as optical couplers are possible. An electrical contact is recommended for use with a fixed connection. The optical coupler should be easily disconnectable to enable data collection via an HUU. This standard incorporates parts of ISO 7498, augmented by further conditions concerning, for example, an optical interface, protocol controlled baud rate switchover and data transmission without acknowledgment of receipt. The preparatory work took as its basis the reference model for communication in open systems ISO 7498.