Communications Card Description ZB4-601-IF1, ZB4-609-IF1 4-8
Moeller 07/01 AWB-C2700-1347GB
4 Preparing the communication cables
The preparation of the cables for the serial interface “COM PORT” and “MPI” is an important factor in the
electromagnetic compatibility (EMC) of the target hardware, both in terms of interference immunity and
emission.
The EMC values stated in the technical data can only be guaranteed if the cables are prepared
according to the following specifications.
4.1 Communications cable
The communications cable must be shielded. The cable shield must be made from copper braid. Use a metal
or metallised connector casing. Connect the cable shield for the card directly to the connector casing. This
ensures that the cable shield is properly connected to the housing of the target hardware via the screws and
the protective metal shroud of the plug connector.
Refer to the relevant operating instructions of the PLC manufacturer for the correct connection procedure for
the cable shield to the PLC. Unless otherwise stated, connect the cable shield to the connector casing of the
PLC.
Provide a potential equalisation cable with a suitable cross-section between control cabinets if the target
hardware and PLC (or another communications partner) are installed in different control cabinets and the
cable shield is directly or indirectly connected to the protective earth at the PLC end. This will prevent the
occurrence of excessive compensation currents on the shield and shield connections, as may occur in the
event of a possible shorting of a device on the protective earth system.
4.2 Cable lengths
The possible cable length and wire recommendations depend on the physical interface used.
Transmission errors may occur if these limits are not observed.
Interface baud rate Length Comments
RS 232 19’200 15 m
9’600 30 m Only suitable for point-to-point connections.
4’800 60 m
RS 422/485 < 100’000 1200 m Using twisted pair communication cables can increase reliability
< 500’000 600 m of the data line concerned.
< 1’000’000 120 m The line terminating resistors must be switched on between the first
and last data terminals!
TTY < 20’000 1000 m
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