how to do an analog trigger with bipolar levels of detection and start acquisition with pre-trig samples

[chouca]

hello,

I use PXI 4472 with accelerometers. I want to trig as soon as the acceleration is out of the window +/-50g and recover the previous samples before the trig. Is it possible to do it?

I try the daq-mx functions trig on analog windows and a number of pretrig samples but without success. My first sample detected is always over 50g, it seems that the number of pretrig samples has not recognized. Anyone to help me?

Thank you. 

[thomas.baudouin]

Hi Chouca,

It should be possible to do what you are trying to do:

type of trigger: analog window triggering (acquire data when the signal leaves the window)

Action caused by trigger: reference trigger

I will try and get a 4472 to check that by myself.

Maybe it would be easier to check the behaviour of the system with a precise voltage generator instead of the accelerometers.

Best regards,