problems with data acquisition setup. Plz help

[Drizvi]

Hi

I'm working on a 50 Hz sinusoidal wave to get measure its voltage through NI DAQ 6025E and board CB 50LP. I was getting the correct waveform till a couple of days back but now the setup seems to have some major problem with it. When ever i start the acquisition process, a DC signal of exact -5V(min value allowed) appears in the waveform graph whereas it should show a sinusoidal signal. The signal has absolutely no variations in it!!... it is a dead straight line at -5 V.

I was wondering what the problem might be?. I have not changed the VI block diagram(also attahed) at all. I'm afraid that i might have damaged the data acquisition card or the CB 50LP board.!.. but do not see any valid reason as to why could it happen.

Please help me, i'm really frustrated with this thing is going!!..

Regards

Danish Rizvi

[Aaron O]

Danish,

Have you tried inputing a known signal to the DAQ card? You could generate a known signal from something like a function generator. What I would do to test the cards Analog Input:

1. Open Measurement & Automation Explorer ( Start Menu » All Programs » National Instruments » Measurement & Automation )

2. Self Test the card (Right Click the card » Self Test)

3. Open the Test Panel for the 6025E (Right Click the card » Test Panel)

4. Acquire analog voltage continuously.

5. Input a known signal into the card (like a 100Hz 2Vpp Sine wave or something)

If you try this and still see a weird value, then the card might be damaged. Let me know if you have further thoughts or questions.

Regards,

Aaron

[Drizvi]

Hi Aaron,

Yes, i fed it with a known signal before and i did it again. And I am still facing the same problem. The card passed the self test but the test panell shows the same output with even the sinusoidal signal applied, i.e -10V dc, with absolutely no variations!. Not even of the minutest order!!

The card wasn't mine so i'm more worried than would;ve been if it was mine!... can u please give me some idea that what sort of a problem. and can it be corrected easily ??

Thanks

Troubled Danish Rizvi

[Drizvi]

Also i'd like to tell you that once i used another card(same 6025E), the readings came just fine with only a minor offset. But since i'm only interested in analyzing the frequency spectrum of the sinusoid signal, this offset would not have much of an effect.

So its not that the slot is damaged, its probably the card i dread!