McQuay MHC Series, Installation & Maintenance Data, Page: 17 / 36

IM 985-1 / Page 17 of 36
MicroTech III Controller with BACnet MS/TP
Communication Module
For­installation­and­operation­information­on­MicroTech­
III­unit­controller­and­other­ancillary­components,­see:
•­­ IM­928­-­MicroTech­III­BACnet­Communication­
Module
•­­ OM­931­-­MicroTech­III­Unit­Controller­for­Water­
Source­Heat­Pumps­Operation­and­Maintenance­
Manual
•­ IM­955­-­MicroTech­III­Wall­Sensor­For­use­with­
Microtech­III­Unit­Controller
McQuay­water­source­heat­pumps­are­available­with­
McQuay­BACnet­communication­module­The­module­
is­programmed­and­tested­with­all­the­logic­required­to­
control­the­unit,­and­is­designed­to­communicate­over­a­
BACnet­MS/TP­communications­network­to­a­building­
automation system (BAS). It can be factory or field-
installed .­
The­unit­controller­is­programmed­and­tested­with­
all­the­logic­required­to­monitor­and­control­the­
unit .­An­optional­wall­sensor­may­be­used­with­the­
communication­module­to­provide­limited­local­control­
of­the­Water­Source­Heat­Pump .­The­unit­controller­
monitors­water­and­air­temperatures­and­passes­
information­to­the­communication­module .­The­module­
communicates­with­the­BAS,­to­provide­network­control­
of­the­Water­Source­Heat­Pump .­
The­module­makes­operational­data­and­commands­
available­on­a­communications­network­using­BACnet­
objects­and­properties:
­

The­network­cable­is­a­shielded­twisted-pair­cable

Network­communications­run­at­76 .8­Kbps .­

DIP­switches­on­the­controller­enable­the­MS/TP­
MAC­address­to­be­set­in­the­range­0-127 .­

A­status­LED­on­the­communication­module­indi-
cates­communication­activity­on­the­MS/TP­com-
munication­network .
Figure 14. MicroTech III BACnet Water Source Heat Pump
Snap-in Communication Module
MicroTech­III­Unit­Controller­with­BACnet
Communication­Module­orchestrates­the­following­unit­
operations:

­ Enable­heating­and­cooling­to­maintain­setpoint­
based­on­a­room­sensor

­ Enable­fan­and­compressor­operation

­ Monitors­all­equipment­protection­controls

­ Monitors­room­and­discharge­air­temperatures

­ Monitors­leaving­water­temperature

­ Relays­status­of­all­vital­unit­functions
An­amber,­on-board­status­LED­indicates­the­status­of­
the­MicroTech­III­BACnet­module .
The­MicroTech­III­unit­controller­includes:

­ A­unit-mounted­return­air­sensor

­ A­unit-mounted­discharge­air­sensor

­ A­leaving­water­temperature­sensor
The­communication­module­provides­access­to­setpoints­
for­operational­control
Available­wall­sensors­include:­

­ Room­sensor

­ Room­sensor­with­LED­status­and­tenant­override­
button

Room­temperature­sensor­with­LED­status,­timed-
override­button,­and­±3°F­setpoint­adjustment

Room­temperature­sensor­with­LED­status,­timed-
override­button,­55°­to­90°F­setpoint­adjustment