Hi,
The equipment is a PXI-8175 (PXI-1031DC), with the following cards: PXI-4472, PXI-6221 and the carrier SC-2345 with four TC02 and two AI03 modules.
When I read a single channel the measurement is good, problem starts when I read more than one channel at the same time, then the temperature readings have different offsets. And if I open one of the temperature channels the others vary (one 4 degrees down, other 2 up and another 10 up). If the analogue input from the AI03 is open also the temperatures vary up and down… when I connect it everything changes again. As I can connect the equipment to a DC battery, I tried this with a 12 volts car battery and happens the same. I’m using a K type thermocouples and “Built in” CJC.
Can any one help me?
Now I discovered that this phenomenon only happens when the acquisition is performed at rates higher than 500 Hz. Does any one know why does it happens and how to solve it.
Where can I find information about this phenomenon?
Thanks,
Marc.
