Can Low Voltage Troubleshooting - Trane Link UX360 Installation Manual

Installation Guide

7. CAN Low Voltage Troubleshooting

Thermostat
(UX360)
System Controller
(SC360)
Troubleshooting steps
Bus Idle
Expected Measurement
Resistance Between DH and DL
Appropriate range can vary depending on the communicating equipment installed on the system
Expected Measurement
Lower than appropriate range
Higher than appropriate range
Resistance Between DH and GND
Expected Measurement
All power to the system must be turned OFF.
1
Device must be powered OFF and disconnected from the CAN bus.
2
8
Distribution Board
• 24 VAC is required to power up the SC360 and UX360
• 24 VAC is required at the outdoor unit for Smart Charge
automatic charging
• 24 VAC is required at the outdoor unit if Load Shed is desired
Description
2 - 4 VDC between DH and GND
2 - 4 VDC between DL and GND
Voltage measured from DH to DL will vary depending on bus
traffic
1
60 +/- 10 ohms can be expected when the SC360,
communicating indoor unit and communicating variable speed
outdoor unit are installed.
90 +/- 10 ohms can be expected with no communicating outdoor
unit installed
Possible short on the bus between DH and DL
Possible open circuit on the bus
2
1 Mohms or greater
Air Handler Outdoor Unit
18-HD98D1-1B-EN