Programming Guide

88 VAV-SVP01A-EN
Troubleshooting
VV550 Communication Loss Procedures
In the event that the VV550 is not communicating properly (No activity on Communication LED's)
inspect the following:
WARNING
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.
1. Incorrect supply voltage/No voltage
• Check Green Status LED.
• Shows solid green when the VV550 is powered and operating normally.
• If Green Status LED is off, check incoming power. Measure the power input to VV550 board
on TB1-1 24VAC input and ground TB1-2.
The supply voltage should be between 19 and 30 VAC (24VAC 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. See
complete wiring diagrams, Figure 59, p. 107 to Figure 66, p. 114.
2. Communication link signal has interference
• Communication link should not be routed near or with any voltage source.
3. Incorrect wire used
• Recommended wire is twisted shielded pair. See VAV Startup/Check out Procedure chapter
for the wiring specifications for VV550
• Check device using Rover service tool to see if VV550 is operating properly. If VV550 does
operate properly, check inputs/outputs for a short.
4. For final step check program by downloading good program using Rover Service tool. See the
Saving VAV Program-portion of the VAV VV550 Controller Programming and Operation chapter.
Note: If still not communicating to Rover service tool and communication link, replace controller.
Communication Failure
LINK
• The TX LED blinks green at the data transfer rate when the VV550 transfers data to other devices
on the link.
• The RX LED blinks yellow at the data transfer rate when the VV550 receives data from other
devices on the link.
Wiring Best Practices
Note: See start up and check out procedures for best wiring practices.