Hi all,
I have a PXI 6115 card, and I record a simple pulse, which lasts 20us. Following settings are used:
- sample Rate: 10MS/s (fastest with this card)
- range: +-10V
- trigger type: AnalogRefTrig. with 1000 presamples
- coupling: DC
- signal is between AI0- and AI0+, shielding on AI0GND
I can record the signal. There is a pulse from 0V to 4V, then back to 0V. My only problem is the trigger level, and I experienced something weird. -> if I set the trigger level to -1.9V, then there is no trigger
-> if I set the trigger level to 2V, there is a trigger sometimes, but only noise, so not my pulse
-> if I set the trigger level to to a value of 2.1 to 6V, then comes the trigger always.
It seems that I have a difference of 2V between the signal and the trigger level, although I use the internal triggering on the output on the PGIA. There is an unaccuracy of 78mV, I have read in the datasheet of the 6115. But where does the 2V come from? Any idea is welcome.
Mitulatbati
p.s. I have already tried the examples from NI.
