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www.DaikinApplied.com 45
IM 1234-1 • BACNET THERMOSTAT
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Topics in this section cover integrating BACnet Thermostat
controllers into a building automation network. These are
advanced topics for control technicians and engineers. The
BACnet Thermostat can function as a stand-alone controller or
it can be connected to a BACnet MS/TP network. The topics
in this section are reference material for control technicians
or engineers that will be installing and setting up a BACnet
Thermostat that is connected to a network.
Connecting to a Network
Before connecting the BACnet Thermostat to a BACnet MS/TP
network, configure the network properties. See the topic
Set
Up Communications on page 16
for the procedure to set the
following.
• Device Instance
• MAC address
• Baud
Use the following principles when wiring the BACnet
Thermostat to an MS/TP network:
• Connect no more than 128 addressable BACnet devices
to one MS/TP network.
• Use 18 gauge, twisted pair, shielded cable for all network
wiring.
• Connect the (–A) terminal in parallel with all other (–)
terminals.
• Connect the (+B) terminal in parallel with all other (+)
terminals.
• Connect the shield to an earth ground at only one location
on the network.
The controllers or devices on the physical ends of the MS/
TP wiring segment must have end-of-line (EOL) termination
installed for proper network operation. Set the end-of-line
termination to ‘On’ using the EOL switches. A 120Ω resistor
across the positive and negative communication wires will also
work as an EOL termination.
Figure 29: BACnet MS/TP Network Wiring
Figure 30: Location of EOL switch
