Synchronous - Simultaneous Analog In Out -- Shared sample clock but.....

[SurfaceSurfer]

Hello,

I am having a bit of trouble synchronizing my analog input and output. I've reviewed pretty much all the examples I could find and can't seem to get my VI to work.

The attached VI is slightly modified NI example and I can't even get that to work right.....got this from their tutorial here

http://zone.ni.com/devzone/cda/tut/p/id/3615#toc1

The idea here is to simply generate a waveform and then output this waveform on the analog output channel (the waveform I'm generating is a simple linear ramp).

What I'm finding (at least I think) is that the analog I/O are not starting at the same time since my AI is only measuring a small portion of the voltage waveform.

I'm runnig out of ideas on how to get this to work so any help would be appreciated.

Labview 8.0/NI USB -6259

best,

james

[SurfaceSurfer]

OK I don't know why but it seems to work now without the sequence structure....

[David L.]

Hi SurfaceSurfer,

The reason why your VI was not working properly is that there was no terminal connected to the Get Terminal Name With Device Prefix.vi, along with the AI being started before the AO. (reverse them in sequence). We want the AO to start first because it is waiting on the AI to start. This way when the AI starts, the start trigger is seen by the AO, and they both start simultaneously.

I would also suggest looking at the shipping example Multi-Function-Synch AI-AO.vi (Help >> Find Examples… >> Hardware Input and Output >> DAQmx >> Synchronization >> Multi-Function)

Message Edited by David L. on 05-11-2007 03:39 PM