Scope seems to trigger no matter what I do

[Chad]

Hi,

I am trying to make a simple interface for a scope, using the IVI class
drivers.
My vi is a slightly modified "Acq Dual Wfm Edge Triggered.vi".

I would like to be able to run the vi, and have the scope wait indefinitely
for a trigger.
Despite my best efforts, the scope seems to trigger as soon as I start the
vi- I capture
blank waveforms.

I've attempted to fix this...
I replaced the "Fetch Waveform.vi" with "Read Waveform.vi"
I changed the "maximum time" input of that vi to "-1". I think this will
allow me to wait
forever. This doesn't seem to work, and hangs up labview.

I've tried to compare the single waveform aquisition vi with the dual, and
don't understand the differences.
Mainly, why does the dual example not in
clude a call to Read Waveform, just
two Fetch waveforms?

Thanks.

[RayFarmer]

Hi Chad,

The Read Waveform has the following action, Initiate and Fetch. The Initiate tells the scope to capture the waveform using the trigger mode setup and the Fetch tells the scope to return the data that it has acquired. Therefore with the dual example, if there was two Read Waveforms it would required two triggers.

You may need to look at how you are commanding the trigger. If you haven't specified this then its probably the default which is Immediate. Which is probably way you are seeing it trigger regardless.

Hope this helps
Ray Farmer