6023E Diff AI Going to 10V after 10 minutes logging in VI Logger -

[Rupey]

I am trying to log the 4-20ma signal from a Temp transmitter to a differential AI on my 6023E using VI Logger.  I am connecting a 270ohm resistor (for test purposes) across the inputs to get my voltage.  Everything works fine for about 10 minutes and then VI logger is showing the voltage oscillating to 10V.  I checked the voltage across the resistor and it will read approx 1.7V at room temp.  The readings are oscillating and sometimes saturated at 10V.  The Test Panel is showing the same thing.  I tried channel 1 and 2 with the same results.  When I cycle power on the transmitter, everything resets ok.

Thanks in advance for any help!

Eric Ruppert

[lrallen]

Eric,

Does this always happen after about 10 minutes even after power cycling the transmitter?  Have you tried a different transmitter?  I am not completely convinced that the problem lies in the 6023E.  Do you have another DAQ device that you could try to eliminate that as a possibility? 

Regards,

lrallen

[Rupey]

Hello,

Thanks for the response!  I finally found an Omega current signal analyzer - fancy current driver.  I get the same thing happening - it happens in about a minute on the test panel - I forgot to point out in VI logger I had it set for about 10 minutes for the log time..  The voltage is at a steady 3V on the test panel and then starts cycling up to a 10VDC max - there is only 3V present all the time.   It still resets after cycling the power.

Thanks,

Eric

[Laura F.]

Hi Eric,

You may check that you are using a proper terminal configuration (differential, RSE, NRSE) for your source.  Depending on the type of source, floating or grounded, you may need to add bias resistors.  You can read more about this in the Field Wiring and Noise Considerations for Analog Signals tutorial.  The behavior you are reporting makes me think that maybe you are missing a bias resistor in your setup or are introducing a ground loop, both topics which are covered in that tutorial.

Please take a look and let us know if you are still having trouble.

Regards,
Laura