GRV-IMA-24 channels dips every now an then by less than 2% of the signal value

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1

Hello,

I am using GRV-IMA-24 with an 2 EPICs to read the input signal of load cells after passing them through a Define Instruments SC-WEI Load Cell Signal Conditioner. The load cells are constantly excited with the same amount of weight for long period of time, so it continuously reading and feeding the signal to the EPIC for trending.

However, every half an hour or so the mA (scaled to 0 - 100 % in the module) signal coming from the GRV-IMA-24 dips by some constant value changing the weight registered for 2 seconds or so and then resume back to its original value. To investigate the issue I used Opto Datalink to track the module signal every 100 msec to confirm the signal dip. Then I went ahead and connected directly to the load cells to read its mV signal through GRV-ITMI-8 module to see if I can track the dip directly from the load cell, I did not see any dips that could could match to the dips in the module signal.

I have attached the datalink data for both load cells and both channels from both modules
6b.zip (333.1 KB)

The question i have, is it worth investigating the module signal? or am i reading too much into it? we use SNAPs with the same load cells (different signal conditioners however) to perform the same process and we dont see any dips with those.

Any insight is appreciated.

2

Can you look at the current with a logging meter to check that its not the output of the load cell conditioner or the power supply?

If I follow the chain… load cell → SC-WEI → GRV-IMA-24
You have checked the load cell, but not the SC-WEI?
I wonder what the power supply to the SC-WEI consists of?

3

I will try that and see how the signal conditioner is behaving.

I went ahead with the assumption that the signal fed to the module is the signal conditioner’s. The signal conditioner is connected directly to the main power line (AC 110V).