Why is the DAQ outputs distorted?

[Gillyme9times]

I am trying to output two voltage sine waves(90 degrees out of phase) from my DAQ card. I use a for loop to create two arrays of 1000 samples each. I then send each of these arrays to my DAQ card for sampling of 5000S/s. One of the outputs(measured on an oscilliscope is perfect while the other clips and is distorted. Why am i not getting twp perfectly good sign waves?Is this a hardware issue?

Please find attached my LabView file.

Thanks,

Gilly

[LV_Pro]

I haven't looked at your vi yet, don't have 8.6 on this machine (please identify the version when attaching vi's), but do have some questions. Are they both set to the same amplitude? Are you looking at them individually (re: single channel scope) or both channels at the same time? Are they both connected to the DAQ inputs in the same way. Usually, if there isn't an actual hardware problem with the outputs, distortion and clipping are caused by; 1) trying to output a waveform of an amplitude greater than allowed, 2) trying to drive a seriously mismatched load. In the later category hooking up to the DAQ incorrectly might cause a problem.

[Gillyme9times]

In this example they are both set to an amplitude of 1 volt(2 volt p-p). The problem i need to solve requires them at ~4 vots and 1 volt. The signal output range of the DAQ assistant is froom 10 volts to -10 volts on each channel...so i think this is not the reason for the clipping.

I am outputting them on two analogue voltage channels.So a cos wave and a sine wave are generated  individually, but then sent to the DAQ assistant to be outputted using two channels.Yes they are both connected to the DAQ in the same way.Is this a problem?

When i tested the outputs on an oscilliscope there was no load connected. If the DAQ card was not connected properly, how would this explain one of my outs being correct?

Can you test this program?

Thanks alot for your time,

G

[ThomasC]

Hi,

In your code you have a graphical display of your waveforms.  I would like to confirm that this is showing your desired waveform before it is being output.

Regards,

Thomas Clark

[Gillyme9times]

Yes the waveforms on the front panel show exactly waht i want.However, once put through the DAQ assistant, the real output is different. I think one channel on my DAQ card might be damaged. Can someone possibly test this for me on their own hardware?

[ThomasC]

Hi,

I am still unsure as to what is causing this problem and could do with a little more information still, which DAQ card and drivers are you using?  What operating system are you running?  How are you measuring the signals?  are you feeding back into your DAQ card or measuring with an external osciloscope?  If you are using a scope are you measuring both signals on the same channel?

Regards,

Thomas Clark

[AnalogKid2DigitalMan]

In MAX, you should be able to run some self-tests on the card. I would try this first and post your results.

-AK2DM