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USB-1808X Analog Out stops and locks at -11.5V & -4.5V





I've purchased several (8) of your USB-1808X and have been very happy with the performance.....until just the other day.  In the middle of troubleshooting a small voltage compare circuit (our 3rd use of this) the analog output apparently went from 0.1V (whichi s what our code was driving it to - OK) to -11.5V!  The mode was 0-10V.  We could not figure out what happen for the life of us.  So, before we rewired another USB-1808X in, we simply plugged in another one (right out of the box) with nothing at all attached and we got our 0.1V (which we moved about 0-10V) and all seemed good, checked our other DAC out along with ADC inputs...but when we went back to double check out original analog out it is now stuck at -4.5V!  Power cycled, etc.  Not sure what we can do from here.  We still have a couple in the sealed box and are afraid to even plug these in as they are not cheap and take months to get.

We certainly have ESD safe enviroment along with DMM that are only measuring V's.  Not sure how this could harm and now we are worried about the previous ones we have already sent out - though they have been in operation for over a year now.


Please help where we can go from here and perhaps other things we can do to troubleshoot.  Thanks,  SSS

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I recommend you get another computer, one that has not seen an MCC product.

Download and install the mccdaq.exe software, in particular DAQami.

DAQami has a function generator output.  I'm using the defaults but set the waveform to sawtooth:


With the USB-1808X configured for single ended analog inputs, I attached a wire from CH0H to AOut0.

I have also sent this analog output of AOut0 to my scope.  It shows this:

1808x_scope capture.jpg

If you cannot get a similar response from your USB-1808X then it is not operating properly for some reason, yet to be determined.

What are your results?


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Sorry for the delay in getting back to this.  I was able to do the loop-back on both USB-1808X's in question and attached the screen shots from AMI showing basically locked far in to the negative region (0-10V mode or not).  Please note: both units go negative immediately on power, never to change.

These were done with another PC using AMI only, though it worries me how one might do this in software only.  (please do tell :)

Also, I was able to review the other 4 units I had previously installed, along with another unit (not ordered with these) at Honeywell and they all looked good regardless of which PC I used.  One curious note:  On power up - all A-outs go to zero, upon setting just ONE of the 2 A-outs, the other will go to whatever it was assigned last.  (Is this from ULx or firmware?)

Thanks and let me know what you think or where I can go from here.

Analog Out 0 loopback to Ain0.PNG

Analog Out 1 loopback to Ain0.PNG

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