BECKHOFF DK9322-0810-0036 - Manual

TwinCAT
TwinCAT, Building Automation
Application Note DK9322-0810-0036
Keywords
M-Bus
Master
counter
consumption measurement
Building Automation
energy measurement
EN 1434
EN 13757
flow measurement
calorimetry
IEC 870
EN 1434-3
M-Bus connection for energy and consumption meters
via TwinCAT
This application example from the ‘Building Automation Sub-bus Systems’ series describes the basic
principles of M-Bus, the KL6781 M-Bus master terminal and the functionality and of the TwinCAT PLC
library M-Bus from Beckhoff. The M-Bus is predominately used in buildings and properties with a large
number of end users. Through serial data transmission a KL6781 M-Bus master can read up to 40 energy and
consumption meters.
1. The M-Bus
The M-Bus (meter bus) is a fieldbus for logging, analyzing, optimizing and controlling energy and process data. It is as used as
a standardized system for reading energy and consumption meters or other end devices or actuators. Signals are transferred
serially from the connected slaves (measuring devices) to a master via a reverse polarity protected two-wire line. Depending
on the application the data are stored or prepared for further processing. The field devices can be supplied with power via the
bus cable. M-Bus is a typical single-master bus, in which the master requests and picks up the data from the slaves. With a
primary address space of 250 addresses, up to 250 slaves can be connected to a master. Via modem interfaces, large distances
can be covered in order to bring together modular extensions or complex systems. The M-Bus system is predominately used
by operating companies supplying a large number of end users (e.g. industrial and technology parks, trade shows, building
management systems, etc.).
Meanwhile the M-Bus has become established as a separate standard in EN 13757. This standard describes the M-Bus for
application via a two-wire bus (part 2) and for radio transmission (part 4). However, standardization at the protocol level is
incomplete. The data telegram features a freely available segment which manufacturers can use for transferring various (non-
New Automation Technology Beckhoff 1
For application notes see disclaimer on the last page