Trane Trane Communicating Thermostats (BACnet) Thermostat User Manual


 
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Figure 4. Terminating BACnet links using BACnet terminators
Product Specifications
Specifications for Communicating Thermostats are as follows.
Network Adapter
The polarity of the connection to the cable is important. From one module to the other it is
important that the same colored wire be connected to “plus” or “+” and the other colored wire be
connected to the “minus” or ”-“.
Important: The Ref terminalshould NEVER beused to wireshields. The 2shields from eachfeed
of the network connection to a thermostat should be wired together in the back of
the thermostat and properly protected to prevent any accidental connection to the
ground.
The joined shield connection should then be grounded at a SINGLE point on the
whole segment. More than one ground connection to a shielded wire may induce
ground loop noises and affect communication.
Table 17. Communicating Thermostat Specifications
Item Details
Media Twisted pair 22AWG-24 AWG, shielded recommended
Characteristic Impedance 100-130 ohms
Distributed capacitance Less than 100 pF per meter (30 pF per foot)
Maximum length per segment 1200 meters (4000 feet) Note: AWG 18 cable
Polarity Polarity sensitive
Multi-drop Daisy-chain (no T connections)
Terminations Always use Trane BACnet terminators at each end of the link.
Maximum number of nodes per segment 30
Baud rate 9600, 19200, 38400, 76800 (Auto detect)