Beckhoff KL6781, Документация

Страница: 28 / 32

M-bus
KL6781 28 Version: 2.0.0
5 M-bus
5.1 Introduction
M-Bus = metering bus
The M-Bus is a fieldbus for the acquisition of consumption data (e.g. energy meters). Further details about
M-Bus can be found under www.m-bus.com. The M-Bus is European standard and is described in the
EN1434 standard. The data are sent serially from a slave (measuring device) to a master (level converter
with PC). Master and slave are connected via a two-wire line that is protected against polarity reversal. With
primary addressing up to 250 slaves can be connected in star, strand or tree topologies. Ring structures are
not permitted. Devices from different manufacturers can be operated on the same bus.
The master controls the communication on the bus by requesting data from the slaves. The slaves can
respond with a fixed or variable data structure. The M-Bus library only evaluates data with variable data
structure (low byte first). The slaves do not communicate with each other. The data have to be requested
sequentially from the slaves.
5.2 Overview
Fig. 11: KL6781 as M-bus master