Measurement Studio for .NET Languages

cancel
Showing results for 
Search instead for 
Did you mean: 

Erroneous Data

I am using threading to display my data.  Every once in a while, and it is only on a select few of our test cells, the chart (and the data going to it) go nuts.  In one test cell it happens to be three adjacent channels out of 68.  It cant be those channels, however, because even the "Target" value goes nuts.  The data written to the file is wrong.  It seems to happen more when someone is using the computer, but not only when someone is using the computer.

Any ideas on what could cause this?


Programming Data Acquisition and Control in Measurement Studio and Labwindows/CVI
Download All
0 Kudos
Message 1 of 3
(2,950 Views)
Hello SCXI...

I am assuming that the problem you are referring to is displayed by the rapid oscillations in your pictures.  From your description, it sounds like the problem may not even be hardware related, since you noted that the "target" value goes crazy also.  I am assuming that this target value is defined completely in software.  Is this true?

For troubleshooting purposes, it would be best if you could try to isolate whether the issue is hardware or software related.  If it is practical to do so, try measuring your physical signal by another means for comparison.  It looks like you are monitoring temperature.  If you are using thermocouples, I know that the voltage generated is very small, but try to get a reading using a voltmeter or oscilloscope during your program's execution and see if these readings fluctuate also.

If you do see the same type of oscillation, consider whether or not you might have any noise sources such as motors nearby.  It is possible that you could be picking up 60 Hz noise from somewhere.  For more information on reducing noise, please refer to the tutorial Field Wiring and Noise Considerations for Analog Signals.

Let us know if you are able to determine whether or not the actual signal is fluctuating, or if the disturbance is somehow software related. 

Best regards,
0 Kudos
Message 2 of 3
(2,930 Views)
The noise is virus software related.  We checked the CPU usage during the spikes and this is what we found.  I either need to change the settings on the PC (against policy and I'm already on 2 strikes 😉  ), change the priority of my thread (if possible), or ask the IT guy for help (who just gave me 2 strikes this week!).  🙂
Programming Data Acquisition and Control in Measurement Studio and Labwindows/CVI
0 Kudos
Message 3 of 3
(2,928 Views)