NBN EN 13757-6:2009

This standard specifies the physical layer parameters of a local meter readout system (Local Bus) for the communication with and the readout of a single meter or a small cluster of meters (max. 5) via a single battery powered readout device (master) which can be connected temporarily or stationary for the communication directly to a meter (i.e. local readout) or via a fixed wiring or a small bus (total cable length max. 50 m, i.e. local remote readout).
For generic descriptions concerning communication systems for meters and remote reading of meters, refer to EN 13757-1.