scope:

This Standard specifies the general requirements and applies toheat meters. Heat meters are instruments intended for measuring theenergy which in a heat-exchange circuit is absorbed (cooling) orgiven up (heating) by a liquid called the heat-conveying liquid.The meter indicates heat in legal units. Part 3 specifies the dataexchange between a meter and a readout device (POINT / POINTcommunication). For these applications using the optical readouthead, the EN 62056-21 protocol is recommended. For direct or remotelocal readout of a single or a few meters via a battery drivenreadout device, the physical layer of EN 13757-6 (local bus) isrecommended. For bigger networks with up to 250 meters, a masterunit with AC mains supply according to EN 13757-2 is necessary tocontrol the M-Bus. For these applications the physical and linklayer of EN 13757-2 and the application layer of EN 13757-3 isrequired. For wireless meter communications, EN 13757-4 describesseveral alternatives of walk/drive-by readout via a mobile stationor by using stationary receivers or a network. Bothunidirectionally and bidirectionally transmitting meters aresupported by this standard.