Issue
How to make local CPH work on a stand-alone MR-VAV-AX.
Environment
MR-VAV-AX
Cause
Even after you select local-CPH in the parameters and connect a contact to the local cph point, the unit probably won't switch modes without further modification. The application is looking for a zero for one mode and something above 1 for the other. Problem is that the factory calibration of the inputs can only be done to within 1 or 2 counts. With the standard conversion coefficient of 5 and 0, you'll still see a value of 5 or 10 for a shorted input. Changing the conversion coefficient wouldn't help because you need an absolute zero.
Resolution
- Even though this is for stand-alone use, you need to connect the unit to an MCI or ISITE Lan.
- You can leave the address at 0 and set address 0 to MR or ASC in the MCU configuration.
- Open the ASC editors and update MCI for address 0 and check the point value for local cph with that input shorted. If it doesn't read 0, proceed.
- Next select Edit, Controller, MR functions. Highlight 0 and hit the Hardware button. These M and Bs are here as a result of the factory calibration.
- Reduce the B on input 02 (3rd entry down) by one or 2 or even 3 so that the local cph input reads 0 when shorted.
- When your done with the first one, you can plug in the rest and use the same MCI database provided you leave them all at 0.
