Problem with analog trigger on 4461/4462

[Torben L]

Hello,

I am using 4461 and/or 4462 to measure an acoustic signal using a ICP microphone on AI0 while using one or more other channels to measure a voltage signal.

The microphone signal is in the 300 mV range, while the other signals may be in a higher range, fx. 10 V range.

The problem is that when I configure AI0 to trig at 30 mV, Rising edge it triggers at a much lower level. Setting the range on the last channel to 30 V makes the problem worse, causing the trigger to on the sligthest noise.

Using the attached example I have seen that the problem is related to the last AI channel on the board, i.e. AI1 on 4461 and AI3 on 4462.

Has anyone seen this or have an idea for a fix?

Using LabVIEW 8.2 and DAQmx 8.3 f3.

Best regards

Torben Laursen