BECKHOFF DK9322-0810-0036 - Manual (Page 5)

TwinCAT
TwinCAT, Building Automation
Application Note DK9322-0810-0036
6. Power supply
The power supply of the slaves and the master is manufacturer-dependent. A wide range of options is available, including
230 V AC external, 30 V DC external, 30 V DC integrated, etc. In addition there are battery-powered field devices which do not
require a power supply connection. In this case the operator should be aware that each meter reading reduces the service life
of the battery.
7. TwinCAT PLC M-Bus library
With the TwinCAT PLC M-Bus library TwinCAT supports M-Bus communication. Thus up to 40 slaves can be easily connected to
the I/O-level via the M-Bus master terminal KL6781 without an additional level converter in a suitable topology (star or strand).
Devices from different manufacturers can be operated on the same bus. The M-Bus library only evaluates data with variable
data structure that are identified by a leading low byte. The TwinCAT PLC M-Bus library also supports secondary addressing,
which is possible with M-Bus for extending the address space. The TwinCAT PLC M-Bus library is free of charge and already
included in the installation package of TwinCAT.
M-Bus
Pulse
Pulse meter
FB_MBUS_...
m³
Water
FB_MBUS_...
Water meter
m³
Gas
FB_MBUS_...
Gas meter
kWh
Heat
FB_MBUS_...
Heat meter
kWh
Energy
Electricity meter
FB_MBUS_...
Address 1...40
CX8090 KL6781
Ethernet
The M-Bus library provides function blocks for any meter
type that can be used for reading out consumption data.
Fig. 3 Connection of M-Bus devices via Bus Terminal KL6781 and programming with TwinCAT PLC library M-Bus
7.1 Benefits for the user
New Automation Technology Beckhoff 5
For application notes see disclaimer on the last page