CODEL
Operation and Maintenance Manual
Issue : A Rev. : 3 Date : 13/11/2018 Ref. : 100351
P a g e | 33
9 Appendix 1: MODBUS Communication & RS485 Connection
The MODBUS protocol output of the Tunnel Tech 500 Series AQM is taken via the 4-way plug. RS485
connection is also available and the following wiring schematic and photograph illustrate the connections for
this feature.
All instruments will be supplied with a 4-way black plastic plug. Connections in the plug are as follows:
Note that in the plug, terminal 1 must be linked to terminal 3 and terminal
must be linked to terminal 2. If
no comms. are present first check the address switch setting and if this does not cure the problem swap the
polarity of TRx lines + and -.
Optional Extra
Diagnostic & Commissioning tool
Illustrated is the serial USB-RS485 interface
(complete with pc software drivers & cable)
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