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PB 4-Input, negative values from correctly attached load cell

Posted: Mon May 23, 2022 4:16 am
by cheister
Hi,
I am using the PhidgetBridge 4-Input and a 100Kg Load cell, which worked perfectly until some days ago where it startet to measure negative values, which vanished, after restarting the computer it is attached to. What could be the reason for this. The load cell is not exposed to extreme temperature changes, nor is it under continuous load and also used far below its maximum. Many thanks, C.

Re: PB 4-Input, negative values from correctly attached load cell

Posted: Tue May 24, 2022 1:38 pm
by mparadis
Did the values gradually drift into the negatives or was it a sudden change? Are these the raw values from the voltageRatio event, or is there some kind of math being applied to them in your program?

You should also double check the terminal blocks to make sure there's a solid connection on all four wires, since a loose connection could cause strange values like this and could be "fixed" if the board is moved in just the right way.

Re: PB 4-Input, negative values from correctly attached load cell

Posted: Wed May 25, 2022 12:45 am
by cheister
Thanks for your reply. It is the raw value read from the phidgets tray control. The values jumped and were normal again after a restart of the host computer. The connections looked fine, but I will double check them.

Re: PB 4-Input, negative values from correctly attached load cell

Posted: Mon May 30, 2022 2:25 pm
by mparadis
It's hard to know for sure what happened, but hopefully it was just an issue with the connection of one of the wires or something. If it happens again, try to capture any sensor data or logs you can, and that will help us figure out what could be causing it.

Re: PB 4-Input, negative values from correctly attached load cell

Posted: Tue May 31, 2022 1:25 am
by cheister
It seems that the cables were the reason. Although they seemed to be fix before, after loosening and retightening them it worked fine again. Should have checked this before posting it... Thanks again. :-)