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Tue Jan 12 08:21:47 2021, anchal, HowTo, CDS, Acromag wiring investigation
Tue Jan 12 11:42:38 2021, gautam, HowTo, CDS, Acromag wiring investigation
Wed Jan 13 16:09:29 2021, Anchal, HowTo, CDS, Acromag wiring investigation
Tue Jan 26 12:59:51 2021, Anchal, HowTo, CDS, Acromag wiring investigation
Tue Jan 26 15:37:25 2021, Anchal, HowTo, CDS, Acromag wiring investigation
Fri Jan 29 17:57:17 2021, Anchal, HowTo, CDS, Acromag wiring investigation
Tue Jan 12 11:42:38 2021
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Acromag wiring investigation
Thanks for the systematic effort.
Can you please post some time domain plots (ndscope perferably or StripTool) to clearly show the different failure modes?
The majority of our AI channels are "Referenced Single Ended Source" in your terminology. At least on the c1psl Acromag crate, there are no channels that are truly differential drive (case #3 in your terminology). I think the point is that we saw noisy inputs when the IN- wasn't connected to RTN. e.g. the thorlabs photodiode has a BNC output with the shield connected to GND and the central conductor carrying a signal, and that channel was noisy when the RTN was unconnected. Is that consistent with your findings?
What is the prescription when we have multiple power supplies (mixture of Sorensens in multiple racks, Thorlabs photodiodes and other devices powered by an AC/DC converter) involved?
I'm still not entirely convinced of what the solution is, or that this is the whole picture. On
, I disconnected (and then re-connected) the FSS RMTEMP sensor from the Acromag box, to check if the sensor output was noisy or if it was the Acromag. The problem surfaced on
, when I installed some new electronics in the rack (though none of them were connected to the Acromag directly, the only common point was the Sorensen DCPS. And between 8 Jan and
, the noise RMS has decreased back to the nominal level, without me doing anything to the grounding. How to reconcile this?