Chapter 5 UCM Wiring and Addressing
94 BMTW-SVN01F-EN
Type of Communication Card: Isolated Comm3
Refer to “Isolated Comm3 Card” on page 49.
Wiring Notes
To establish wiring connections between the UCM and the BCU, Trane
requires that you use the communication-link wire specified in this man-
ual. For wire selection specifications, see “UCM Communication-Wire
Characteristics” on page 55.
Use fiber-optic modems for building-to-building communication. If fiber
optics are not used, building-to-building communication wiring requires a
Transtector transient protector at each building. You can purchase Tran-
stector protectors through Trane. Contact your local Trane sales office for
details.
In a daisy chain configuration, use one pair of wires that start at the BCU
and go to all UCMs in a continuous loop. A branch configuration is possi-
ble if you need to tap into a daisy chain. Limit the total aggregate length
of the wiring for each communication link to 5,000 ft (1,524 m).
To connect the communication wiring:
1. Attach one end of the communication-link wiring to TB2 on the BCU.
For the location of TB2, refer to Figure 16 on page 47.
2. Attach the other end of the communication-link wiring to the PCM at
the TB2 terminal. For connection points, refer to the PCM literature.
To connect the shield:
Connect the shield at the BCU (TB2) to provide a drain for RFI/EMI, and
then splice it with other PCM UCM shields at the PCM UCM end. Tape
the shield at the last PCM UCM in the chain to prevent any connection
between the shield and ground (see Figure 45 on page 95).
IMPORTANT
UCM ground loops will cause a malfunction.
Note:
Observe the polarity throughout communication links.
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