DAQCard 6036E analog input value goes gradually from 0 to 5V and doesn't change anymore

[celekorca]

I have installed DAQCard 6036E on my PC (Dell Inspiron, core 2 duo) OS win7/32 and winXP.
First I installed drivers 9.2.2 DAQmx, than Labview 2010 and signal express 2010. Afterwords i installed the hardware.

The system recognized it and it says that the device is working.

I try to read analog input through 6063E and the result increases up till 5V.
Then when i start again is still 5V without have no input signal.
I tried to read the input signal from different NI softwares (labview, signalexpress, Measurement&Automation, i tried even MATLAB) but the result
is still the same.

I restart my PC and then the measured value starts from around -200mV and again increases till 5V.

Can you please tell me what is wrong with my system.

Regards

[P.Sanders]

Hi, sounds like you may be having grounding issues.

1. what signal are you measuring? e.g. is it a constant DC voltage?

2. Is it a grounded signal source?

-Ciao

[celekorca]

Thanks a lot for your answer.

I am measuring EEG brain signal.For the moment i have only three input signals because i'm using only three electrodes.

Do I have to ground the Card my self?

And if I have to, how should i do it: just add one channel as ground (i.e. a0) or...?

As for the signal source it comes from a NEC-EEG device and the output is a signal measured with difference to ear potential. The device itself is grounded and the computer as well. but there is NO Ground input from EEG Device to the DAQCard. The only inputs are electrode channels.

Regards

[Steve.J]

I've done this kind of setup before and the best arrangement is usually to configure the DAQ cards in NRSE mode (non-referred single-ended).  Bring all your analog outputs from the EEG machine to the each Analog Input on the DAQ card and connect the EEG signal ground (usually somewhere on the same connector as the analog outputs on the EEG machine) to the AISENSE input on the DAQ card.

[celekorca]

Thanks a lot.

It works fine now. I did earthing and everything as you suggested and now is reading appropriately.

Best Regards