ni 9237 calibration -200077 - SOLVED

[wnb]

I'm trying to calibrate NI 9237 + NI 9945 quarter bridge strain gage in ni max.

I get Error -200077 occurred at strain gage calibration.

Possible reasons:

Requested value is not a supported value for his property,

Property AI.Min

Requested value -1.0e-3

Valid values begin wih 18.8988984e-6

Valid values end with 103.843984e-3

Channel name: strain

I tried everything, different strain gages, different 9945's different 9237's, different cables, different computers. everything.

I changed every setting I could find in ni max.

I searched forums and inernet and what is there is not helping.

Any ideas?  Please?  I'm so desperate.

[mikeporter]

In the midst of all your reading did you try reading the error message. It tells you what value is incorrect and the acceptable range of values.

Mike...

[wnb]

Yes, of course, but it's not like I can change the value of the numbers directly.

I tried to set the upper and lower range limits.

While that changed the numbers in the error message, it did not solve the error, regardless of how high or low I set the limit values.

[mikeporter]

So what is the message you get when you set the min value between the two limits specified in the error message?

Mike...

[wnb · Accepted solution]

I just got the same error message over and over.

What went down: When I set my min limit within the highest and lowest allowable values specified in the error dialog window, and then tried again, I got the same error all over again, but the highest and lowest allowable values shown in the window had changed to completely different numbers.  This happened several times.  No matter what I set my limits to, the max min allowable values would always change, so it would error out every time regardless of what I entered.  Sometimes it would complain about the shunt calibration gain factor, that it couldn't set it to either "+inf" or "-inf".  Looking closely at the calibration window, I noticed that NI MAX was reading the same strain value, both with, and without, the shunt resistor connected.  When the calibraion subtracted Y2 - Y1, it got zero, and the inverse of zero is infinty.  That's when I knew for sure it was something in my wiring and started looking into it more deeply.

Cause: Short in the lead wires running to the strain gage.  When the specimen was assembled and bolted onto the fixture, the wires were obscured so that noone could see them, and they were crushed between two metal components.

Solution:  Check for shorts or other issues in the strain gage wiring itself.  I imagine if the strain gage circuit is open, then we would probably see the same error from NI MAX in that case as well.

Recommendation:  I would request NI to add some more helpful information in the error dialog box, to suggest to the user to check wiring, etc.