Odyssey Symbio VFD Communication Troubleshooting
Overview:
Information discovered in Tech support from testing
W-017 Ctrl.word TO fault
The VFD in the SZVAV / 2 Speed Air Handler communicates to the Symbio 700 UC via Modbus.
The Symbio 700 configuration should be set to System Type = VVZT & Indoor Fan Type = Variable Speed or System Type = CVZT & Indoor Fan Type = Multispeed
This Air Handler can be identified by looking at Model Number.
Digit 15 - D = 2 Stage Airflow/Single Zone VAV (Symbio Cond Only)
Below are some troubleshooting tips for communication issues.
If communication is normal, the COM led on the VFD keypad will fast and slow flash.
If the VFD is not communicating, the COM led on the VFD keypad flashes once every 5 seconds.
If the field comm wires are crossed, the COM led on the VFD keypad will be on steady.
If one of the field comm wires is open, the COM led on the VFD keypad will be off.
Communicating VFD Info:
If VFD Parameter 8-01 is set to Digital only (on a communicating VFD) the fan won't run and you get an Alarm on the Symbio for Supply Fan Failure. (should be set to Controlword Only)
If VFD Parameter 8-30, 32 or 33 are set wrong (on a communicating VFD) the fan won't run and you get an Alarm on the Symbio for Supply Fan VFD Communication.
If communication is normal, the Com LED on the VFD keypad will fast and slow flash.
Normal VFD com voltage 4.73 to 4.15 VDC pulsing approximately 10 times a minute, no pattern.
If the modbus wires are crossed between the Adapter Board and the Relay Board you get 4.39 VDC steady on Modbus + to Modbus -, the Com LED on the VFD keypad will be ON STEADY and you will get W-017 Ctrl.word TO on the VFD keypad.
Example – 1 and 2 crossed, 1 and 3 crossed.
If the one of the Modbus wires are open, the Com LED on the VFD keypad flashes once every 5 seconds, the VFD keypad display would NOT have a W-017 Ctrl.word TO, but the Symbio Board will show VFD not communicating.
If Modbus + is open – terminal 68 to 69 will read 3.4 VDC, 68 to 61 will read 3.5 VDC, 69 to 61 will read .1 VDC.
If Modbus – is open – terminal 68 to 69 will read 4.8 VDC, 68 to 61 will read 4.8 VDC, 69 to 61 will read 4.8 VDC
If all 3 of the field comm wires are open, you will get 4.95 VDC steady at the Symbio 700 (UC), the Com LED on the VFD keypad will be OFF and you will get W-017 Ctrl.word TO on the VFD keypad.
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For Odyssey Model with 14th digit as "A", follow the link below for VFD Parameters
Odyssey Symbio VFD Programming Parameters
For Odyssey Models with 14th digit a "B", follow the link below for VFD Parameters
Odyssey Symbio 2023 DOE VFD Parameters
WARNING:
Information in this article is intended for use by individuals possessing adequate backgrounds of electrical and mechanical experience and who comply with all federal, state, and local laws, rules, orders, or regulations related to the installation, service, or repair of a heating or central air conditioning product. Any attempt to install, service, or repair a heating or central air conditioning product may result in personal injury and/or property damage. The manufacturer or seller cannot be responsible for the interpretation of the information contained herein, nor can it assume any liability in connection with its use.