Uc400 Controller Communication Loss - Trane Tracer Uc

UC400 Controller Communication Loss

Live Electrical Components!
During installation, testing, servicing and troubleshooting of this product, it may be necessary
to work with live electrical components. Have a qualified licensed electrician or other
individual who has been properly trained in handling live electrical components perform these
tasks. Failure to follow all electrical safety precautions when exposed to live electrical
components could result in death or serious injury.
In the event of communication loss (no activity on the LINK or IMC LEDs), check the following:
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VAV-SVX07B-EN
The TX LED blinks green at the data transfer rate when the UC400 controller transfers data to
other devices on the link.
The RX LED blinks yellow at the data transfer rate when the UC400 controller receives data from
other devices on the link.
Check for incorrect supply voltage/no voltage.
– Check Marquee LED for the following:
– Displays solid green when the UC400 controller is powered and operating normally.
– Displays solid red when the UC400 controller is powered, but represents low power or
a malfunction.
– If marquee LED is solid red, check incoming power. Measure the power input to UC400
controller on XFMR 24 Vac input and
The supply voltage should be between 20.4 to 27.6 Vac (24 Vac cataloged). However,
voltages at either extreme may result in system instability.
– If no voltage, check up stream of controller to see were voltage has been interrupted.
Refer to the section,
– Check for correct addressing on the UC400 controller.
Each UC400 controller on the BACnet link must have a unique rotary switch setting,
otherwise communication problems will occur. There are three rotary switches on the front
of the UC400 controller. Use these switches to define a three-digit address when the UC400
controller is installed in a BACnet system (for example, 107, 120, and so on), whether with
other Trane BACnet controls or controls from another vendor. This three-digit rotary switch
setting is used as both the BACnet MAC address and the BACnet Device ID.
Note: Valid addresses are 001 to 120. Sequential addressing without gaps is
recommended.
– Verify that there are no duplicated addresses on the communication link.
Check for alarms or diagnostics with Tracer TU service tool, and check that the communication
link avoids interference. Communication link should not be routed near or with any voltage
source.
– The following wiring best practices are recommended:
– Strip no more than 2 inches (5 cm) of the outer conductor of shielded wire.
– Avoid sharing 24 Vac power between unit controllers.
– Ensure that 24 Vac power supplies are consistently grounded. If grounds are not
maintained, then intermittent or failed communication could result.
Check that twisted shielded pair wiring is used and observe the following guidelines (refer to
the section, "Wiring Installation, " p.
WARNING
.
"Appendix: Typical Trane Factory Wiring Diagrams, " p.
13):
Troubleshooting
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