Does the AO on a PXI-6071e have any protection for too much power draw?

[pwb2103]

I had the analog output of my PXI-6071e set to output 10 volts that then went to the input of an amplifier. The output of the amplifier was connected to a diagnostic. Something went wrong and the diagnostic got grounded. The amp went to its current limit and after that labview kept giving me strange errors. I'm trying to troubleshoot and I fear I may have destroyed my PXI-6071e by asking it to output too much power.

Now the AO on the PXI-6071e is constantly outputting ~14v and the inputs aren't reading anything. Does anyone know if I am right in my suspicions that I blew the card or is it possible that there is some built in protection? Any suggestions for troubleshooting if there is still hope?

Thanks,
Paul

[J_Thomas]

If your AO channels are constantly outputting a voltage above its maximum of 10 V, and the analog inputs are not working, you may need to send your board in for repair.  The quickest way to get assistance with a repair will be to go to ni.com/support and click on “Ask an Engineer” to request support via phone.

According to the specifications for the PXI-6071e the inputs have a maximum over voltage protection of +/- 25 V and ideally each input should stay with +/- 11 V of ground.  The analog output channels have a maximum current of +/- 5 mA protected by a short-circuit to ground.

Questions:

• What strange errors are you seeing in LabVIEW? If you can post the exact behavior or error code and description.
• Are you using a Test Panel in Measurement & Automation Explorer (MAX) to test the AO and AI? Are you using an external multimeter to check the AO output?
• Can the analog inputs read a known voltage? Say from a 9 volt battery or some other source?

Suggestions:

• Try the card in another PXI slot.
• Try resetting the device in Measurement & Automation Explorer (MAX)
• Download and run the DAQ Diagnostic Utility. 

The version will depend on what hardware driver you are using.

Version 2.0 of the DAQ Diagnostic Utility is only supported in NI-DAQmx 8.3 and later. If you are using NI-DAQmx 7.5, 8.0 or 8.1, please use version 1 (there is a link for version 1.0 on the page for version 2.0)

[pwb2103]

Hi Jared thanks for your help!

For your questions,
I can no longer reproduce the errors, they went away after I turned the chassis and the computer off and on.  They were saying something about trouble with the master timing, but I didn't record them and I no longer have the exact details.  Now the card gives no errors but also measures no signals and has a large offset on everything.

I used a multimeter to check the AO output, I tried a test panel and it is giving me the same behavior as my normal labview control program: -10v on all the AI 14.3v on AO1 and ~.5 volts on AO2.

The analog inputs cannot read a known voltage.

I also tried the card in a different slot, the problem followed the card to the new slot (cards in other slots are not having and problems). 
Resseting the device in MAX did not change anything and the diagnositc utility gave me the following:
----Begin Log----
Selected Device: 4_6071E
Device Type: PXI-6071E
Serial Number: *******
Device Support: (PASS)
NI-DAQmx Version: 7.5 (PASS)
Device Reset: (PASS)
The device was last self-calibrated on: 4/9/2004 6:54:22 PM
Running Calibration ...   FAILED for the following reason: 
Error -200545 occurred at DAQmx Self Calibrate.vi
Possible reason(s):
Self-calibration failed.  The self-calibration date has not changed.

Disconnect the device from external signals, as they might introduce noise.  Externally calibrate the device to recalibrate the onboard voltage reference that is used for self-calibration. 

-------------------- Testing Counters... --------------------
Testing CTR Buffered Pulse Generation...   (PASS)
Testing CTR Single Pulse Generation...   (PASS)
------------------- Testing Analog Input... --------------------
Testing AI Ground Reference...   (FAIL)
************ Test FAILED for the following reason ************
Analog Input was not within tolerance for ground reference.  Expected to read: 0.000000  Actually read: -10.000000
*******************************************************
Testing AI Voltage Reference...   (FAIL)
************ Test FAILED for the following reason ************
Analog Input was not within tolerance for reference voltage.    Expected to read: 5.000000  Actually read: -10.000000
*******************************************************
Testing AI Finite Sample Clock...   (PASS)
Testing AI Finite Sample Clock Frequency...   (PASS)
-------------------- Testing Analog Output... --------------------
Testing AO Finite Sample Clock...   (PASS)
Testing AO Finite Sample Clock Frequency...   (PASS)
Testing AO Single Point...   (FAIL)
************ Test FAILED for the following reason ************
This test failed to output 9.000000 Volts on 4_6071E/ao0.  The actual value written was -10.000000.
*******************************************************
Testing AO Accuracy...   (FAIL)
************ Test FAILED for the following reason ************
This test failed to generate a voltage waveform with an error of less than 0.385802 Volts on 4_6071E/ao0.  The actual average error was 10.000000 Volts.
*******************************************************
-------------------- Testing Digital IO... --------------------
Testing DIO Lines...   (PASS)
Testing DIO Ports...   (PASS)
---End Log----

It looks to me like I will probably have to send the card in for repairs.  The only hope I see is the line right after it fails the selfcalibration that says: Disconnect the device from external signals, as they might introduce noise.  Externally calibrate the device to recalibrate the onboard voltage reference that is used for self-calibration.

Perhaps the onboard voltage reference got set way off and it can be adjusted?  I'll see if I can figure out how to recalibrate that, seems worth a shot.  Any further ideas are very welcome.  Thanks again for your help.

Cheers,
Paul

[J_Thomas]

Hi Paul,

Based on your last post, it seems likely that there is a problem with the onboard reference voltage.  I am not sure if recalibrating the card will correct the problem, especially if there is actual damage to the hardware components.  The quickest resolution is to send it in for repair, but if you have the time and would like to avoid the expense of a repair if possible it never hurts to try other options like calibration.