Simultaneous Measurement with 6120 card using DAQ legacy

[kevrasm]

I'm incorporating a PXI-6120 card into our test system for simultaneous measurement.  We currently have  a wrapper built in VB for the Ni-DAQ legacy driver.  There's a pretty tight deadline on getting this integrated and since the 6120 card is compatible with the Legacy driver, I'd like to use that instead of DAQmx.  I've been looking through the AI read commands in Ni-DAQ legacy and they all seem to call out a single channel, so there would be a time delay in geting all 4 channels measuring simultaneously.  I'm unable to find a command that selects specific channels or even all of the analog input channels to begin measuring at the same time (true simultaneous measuement).  I've believe I saw this capability with DAQmx.  How is this done with DAQ legacy?  

[Rick Riper]

I haven't worked in PXI, but have done a lot of VB6 programming with the legacy DAQ stuff.  Sounds like what you need to do is a SCAN - which is multi-channel.  There are different ways of doing this depending on whether you want to start the daq device collecting data and then have your app do other stuff, coming back periodically to check if the data collection is done.  Or if you're simply looking to grab a quick set of readings, check out the Scan_Op command.

I believe in most (all?) scans you need to collect more than one reading per channel - but you can do as few as 2 per - then average them.

Hope this helps!

Rick

[kevrasm]

Thanks a lot.  I looked at those functions but didn't think I could use them because they are listed as working only with an E series device, the PXI-6120 is an S series device.  I'll give it a try.