NI myDAQ signal died out

[enter01]

I'm using an NI myDAQ. I generated a sine wave input signal using Matlab, saved it in a text file,and sent it via the Analog Output. I then got the input and output signals from 2 Analog Inputs. They looked  fine for 2-5 minutes and then the signals died out and became  straight lines with noise. Please advise...how to fix this?.. Thank you.

[lis@jiang]

Hello enter01,

Can you provide some clarification to your current set up?  You said that you were generating a sine wave input.  Is that on an AI channel that you're reading, saving, and then outputting?  Or are you generating a sine wave to output through AO directly?

You're also reading from two AI channels.  Are these completely separate signals from that generated sine wave?  Is one of these channels reading the input from the AO channel outputting the sine wave?  What is the other channel reading?  Where is this signal coming from?

After 2-5 minutes, these signals die out and become straight lines with noise.  Does it look like these noise readings are around 0V?  If not, is there a DC offset?

Are you doing all your programming in LabVIEW, other than just generating the sine wave?  If so, can you use the following examples to run this and see if you're observing the same behavior?  Continuous Analog Acquisition, and Continuous Analog Generation.

Thanks,

Lisa