I am a journeyman HVAC mechanic with limited experience on controls.
Currently having issues with the final integration of WaterFurnace water to air heat pumps and Siemens Apogee system.
The location is a shopping mall. The PXCM controllers are located in each quadrant (max 32 units per trunk)
I have installed a custom app into each heat pump. Majority of the units are single stage; however we have a handful of dual compressor units located throughout the mall.
All comm trunks that are exclusively single stage (Only one program file per PXCM controller) seem to have no communication issues.
The PXCM controllers that have dual stage compressors and single stage compressors are giving us problems. Although they all have the same programming (either single stage or dual compressor programming), some units will show failed points, but others don't.
Some units in the middle of the daisy chain will show all points failed, but units downstream display all info (Doesn't appear to be a short or ground)
Things I have done:
-reflashed the boards with no luck.
-Swapped out a FX10 board that was working fine on one PXCM controller, and installed it in a unit that was showing failed points on a different PXCM. (The problem remained with the heat pump/PXCM. The FX10 that showed failed on one PXCM, worked fine on the different PXCM)
-One trunk was spread out over 2 levels. The system showed 6 failed units, 3 on each level. We isolated each level, so they could be viewed individially on the DDC. When the upper floor was viewed on its own, no problematic units showed (3 showed previously). When the lower level was viewed, 3 units showed failed points, and intermittently showed space temp values only.
I dont believe the programming is the issue.
I ran BACspy and confirmed all mac addresses are as they should be.
I scanned the system with BACnet Explorer and am able to view all units most of the time (Sometimes they dont all show up)
Perhaps it could be:
-PXC mod expansion for BACnet?
-BACnet card on FX10 board
-Different BACnet on the FX10???
Any input would be greatly appreciated.