Troubleshooting guide

Page 20 of 28 / OM 931-3
MicroTech III Controller with BACnet®
Communication Module
For installation and operation information on MicroTech III
unit controller and other ancillary components, see:
■ IM 928 - MicroTech III Water Source Heat Pump BACnet
Communication Module
■ IM 955 - MicroTech III Wall Sensor For use with
Microtech III Unit Controller
Daikin McQuay water source heat pumps are available with
Daikin McQuay BACnet MS/TP communication module that
is designed to communicate over a BACnet MS/TP commu-
nications network to a building automation system (BAS). It
can be factory or eld-installed.
The unit controller is programmed and tested with all the
logic required to monitor and control the unit. An optional
wall sensor may be used with the communication module to
provide limited local control of the water source heat pump.
The unit controller monitors water and air temperatures and
passes information to the communication module. The mod-
ule communicates with the BAS, to provide network control
of the water source heat pump.
The module makes operational data and commands available
on a communications network using BACnet objects and
properties:
■ The network cable is a shielded twisted-pair cable
■ Network communications run up to 76.8 Kbps
■ DIP switches on the controller enable the MS/TP MAC
address to be set in the range 0-127
■ Four green status LEDs on the communication module
indicate communication activity on the MS/TP
communication network and with the unit controller
Figure 10: MicroTech III BACnet MS/TP Snap-in
Communication Module
MicroTech III Unit Controller with BACnet MS/TP Commu-
nication Module orchestrates the following unit operations:
■ Enable heating and cooling to maintain setpoint based on
a room sensor
■ Enable fan and compressor operation
■ Monitors all equipment protection controls
■ Monitors room and discharge air temperatures
■ Monitors leaving water temperature
■ Relays status of all vital unit functions
The MicroTech III unit controller with
communication module includes:
■ Return Air Temperature sensor (RAT)(eld-installed)
■ Discharge Air Temperature sensor (DAT)(eld-installed)
■ Leaving Water Temperature sensor (LWT)
Note: Refer to IM 956-X for details to install (RAT) & (DAT)
sensors.
When an optional wall-mounted room temperature sensor is
connected to the unit controller, the Return Air Temperature
(RAT) sensor must not be installed. A wall-mounted room
temperature sensor and the return air temperature sensor
must not be connected simultaneously or the unit will not
operate properly.
CAUTION
The communication module provides access to setpoints for
operational control
Available wall sensors include:
■ Room sensor with LED status and tenant override button
■ Room sensor with LED status, tenant override button, and
±3°F setpoint adjustment
■ Room sensor with LED status, tenant override
button, 55° to 90°F setpoint adjustment