Strange DAQmx control behaviour

[Torten]

I am developing a simple IO application for a remote customer. I am using labview 7.1 and the customer 8.5 - both with the latest daqmx.

The program takes in two voltage signals trough a pci-6024e board - I use simulated I/O and simulated signals to verify my code. At my end everything looks fine - but when my customer tries to run the program - and selects the input channels where he has his signals the second channel becomes a copy of the first. If for example he in the daqmx task/channel control selects a0 and a1 - the input signal fro a1 is the same as in a0.

I have tried to send a compiled version with the same result.

Any suggestion for a solution/approach would be appreciated.

I have attached som code (250Hz and 5 samples per readout)

[johnsold]

Torten,

Does the customer have a signal connected to the second channel, and if so, does it have a low source impedance?

What you described sounds like the capacitors in the multiplexer charging to the value of the first channel and not being discharged or charged to the value of the second signal before the conversion is made.

If he looks at only the a1 channel does he get the signal from that source?

What happens if he reverses the connections at the board inputs?

Lynn 

[Torten · Accepted solution]

Hi johnsold, thank you for suggestion - however the problem turned out to be the customer not configuring the input signal correctly. The input signal was set to differential while the wiring was single ended - when changed to RSE it all worked fine. I am not sure why the signals were similar earlier though.