Varitrac comm. Check

[jayhawker]

What is the procedure for checking the communications between the UMC in the unit the Varitrac contol panel and the Centeral control panel. I split tjhe comm. wires in the unit and read 1.9 vdc on both wires. I show data being recieved via the green LED on the UMC flashing but the red LED that indicates data being transmited never flashes. Replaced the UMC and the system picked up the communications to the UMC board but never started the system, same condition with the red LED. Cycled the RTU thru the test mode heat. cool and the blower all function OK.

[scrooloose]

You need to supply lot more info on that.

New CCP or old? How many total UCM's on the CCP, board in the RTU is called a TCI, are you talking about the RTU or VAV comm lights.

[jayhawker]

10 year old CCP

8 UCM's on the network

Comm LED's on the TCI board in the RTU

[mallron]

You're going to need to upload the ccp and see if it is commanding the RTU to run.

Not trying to bust your balls, but who paid for that board you replaced? It's not good practice to replace boards unless you are sure it's bad or you have exhausted all other options.

-JB

[jayhawker]

we switched a board from another unit to confirm that it was bad. The unit is commanded to run according to the computer terminal onsite

[mallron]

Thanks for correcting me.

Can you read points from the RTU on the terminal?

-JB