Modbus Network Connector; Board-To-Board Connector; Figure 3. Modbus Communication Module And Knockout - McQuay MicroTech III Installation And Maintenance Manual

BUS LEDs
The BUS LED indicates the communication status between the Modbus Communication Module and
the Modbus network. The table below describes the status of the BUS LED.
BUS LED Color
Green
Red
Orange / Yellow

Modbus Network Connector

An RS-485 connector connects the Modbus Communication Module to the Modbus Network and has
-
three pins: + , , and Ref. The Modbus Communication Module has two RS-485 ports, but only the
top connector (Channel 0) is used (see Figure 2).

Board-To-Board Connector

The board-to-board connector connects the MicroTech III Chiller Unit Controller to the Modbus
Communication Module (see Figures 3, 4, and 5).

Figure 3. Modbus Communication Module and Knockout

Knockout
permanently
removed
7
Meaning
The unit controller is capable of communicating to the network.
The unit controller is not capable of communicating to the network.
Communication module is initializing.
Board-to-board
connector
Slot in module must line
up with baffle in board-
to-board connector
IM 969