Invertek Optidrive Eco ODV-3-220043-1F12-TN User Manual page 58

Modbus RTU and BACnet MSTP connection should be made via the RJ45 connector. The pin assignments are as shown in section
1 1. 1 . RS-485 communications.
 Modbus RTU and BACnet MSTP networks require three conductors for best operation and to eliminate common mode voltages
on the drive terminals:
o RSR85+
o RS485-
o 0 Volt Common
 Connection should be made using a suitable dual twisted pair, shielded cable, with a wave impedance of 120R.
 Use one of the twisted pairs to connect to the RS485+ and RS485- of each drive.
 Use one conductor of the remaining pair to connect together all the 0 volt common connection terminals.
 The cable shield should be connected to a suitable clean ground point to prevent interference with the screen maintained as close
as possible to the cable terminations.
 Do not connect the 0 Volt Common, RS485- or RS485+ to ground at any point.
 Network terminating resistor (120R) should be used at the end of the network to reduce noise.
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