Serial Communications; Rs-485 Communications - Invertek Drives Eco Optidrive ODV-3-220043-1F12-SN User Manual

10. Serial Communications

10.1. RS-485 Communications

Optidrive Eco has an RJ45 connector located within the wiring enclosure of the drive. This connector allows the user to set up a drive
network via a wired connection. The connector contains two independent RS485 connections, one for Invertek's Optibus Protocol
and one for Modbus RTU / BACnet MSTP. Both connections can be used simultaneously.
The electrical signal arrangement of the RJ45 connector is shown as follows:
 The Optibus data link is only used for connection of Invertek peripherals and inter-drive communication.
 The Modbus interface allows connection to a Modbus RTU network as described in section 10.2. Modbus RTU Communications.
10.1.1. RS-485 Communications Electrical Connections
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.
www.invertekdrives.com
1
Not used
2
Not used
3
0 Volts
4
-RS485 (PC)
5
+RS485 (PC)
6
+24 Volt
7
RS 485- Modbus RTU / BACnet MSTP
8
RS 485+ Modbus RTU / BACnet MSTP
Warning:
This is not an Ethernet connection. Do not connect
directly to an Ethernet port.
Warning:
When using Modbus RTU or BACnet, ensure that the
0V signal (T3) is also used to avoid comms errors
and potentially damaging common mode voltages.
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