Alerton sensor calibration

[MatrixTransform]

Without saying exactly where in the world we are, the local Alerton people are a little hostile here ... including to their customers it seems!

We dont usually work with Alerton but sometimes cant avoid being asked to tweak a system here or there. We mostly have our heads around Envision so we can carry out programming and graphics changes when necessary.

The question continually comes up regarding Alerton thermistors.... how to calibrate a temperature sensor in the Alerton world? Particularly for VAV-SD2A controllers...somebody is now asking how to do the same for some TX(Ibex) controllers too.

Any help would be much appreciated.

[HVAC_CxA_1]

I've played around with the zero & range settings (input config) with limited success. If it's a simple offset, you'll have to add an addition DDC function to the AI and an AV offset value (added to display somewhere) then write to another AV. You'll have to go through the DDC program and change all references to the AI and change to the new AV.
I've had instances where the controller inputs were cycling as if it had excessive EMI and making the input bouncy. I have a DDC filter program that really smoothes out.
Let me know if you would like some custom DDC work - i have extensive experience.

[MatrixTransform]

Thanks...I'm starting to understand this may well be the case....though i dont recall seeing zero & range settings anywhere...if I did, I would have been on that like a beaver on a log!

The problem with a programmed solution is that each program needs a different offset so a global program change to every vav will also wipe out the calibrations. grumble

[HVAC_CxA_1]

Yeah, there is no zero/range adj for thermistors or microsets.
If you save all point data (present values & VAV calibrations) for all controllers on the device mgr, you can then send globally along with the revised DDC program thereby restoring all points - should be somewhat seemless. Just beware - your communication needs to be solid. Watch the user request monitor and make sure data is being uploaded and not dumped/failed during the save.