8 Wiring diagrams
8.1 RS-485
The figure shows the configuration of the RS-485 interface with several nodes in a
Modbus segment according to the specification ’Modbus over serial line’.
Figure 8.1: RS-485 with several subscribers
ITr
A twisted, shielded cable must be used as a bus cable
IDv
Passive spur lines must be as short as possible
Masse
The ground connection of all bus nodes must be connected to each other and
connected to the end of the bus, if possible at the bus master
LT
The bus line must be terminated at both ends with terminating resistors of 120
Ohm between lines A and B.
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