Wiring the RS-485 Modbus RTU terminal
Installing the Network Management Module – 12
1.
2.3.5 Configuring the termination
If the INDGW card is the last device installed in the network chain or the length of the network cable is excessive, termination
needs to be enabled.
Termination is used to match impedance of a node to the impedance of the transmission line being used. When impedances are
mismatched, the transmitted signal is not completely absorbed by the load and a portion is reflected into the transmission line.
To enable the on-board termination resistor (120Ω):
Locate the termination switch that is located on the top of the Modbus Network Module.
Belden 9843-24AWG or equivalent cabling (3 twisted-pair shielded 120Ω cable with ground) is recommended.
No more than two termination points should be used in the RS-485 network.
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