Trane Trane Communicating Thermostats (BACnet) manual Product Specifications, Network Adapter

Figure 4. Terminating BACnet links using BACnet terminators

Product Specifications

Specifications for Communicating Thermostats are as follows.

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)

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 terminal should NEVER be used to wire shields. The 2 shields from each feed 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.

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