DAQmx Syncronization Method Choices?

[mcduff]

Sorry I have no code to show, looking in your direction Bob Schor.

My question is a Sir Jeff B or Kevin Price type of question.

I have recently purchased  a Delta Sigma PXI card and SAR card that I want to synchronize together. There are useful discussion forums, discussion forum, and also white papers white paper. Both of the linked methods refer to a low level synchronization method, that is, using specific DAQmx functions to link the cards together.

DAQmx also offers Channel Expansion, another white paper,  where the DAQmx API automatically takes care of all of the synchronization.

Having never done this before is there an advantage to either method? The easiest route is Channel Expansion, but maybe it does not work well? Has anyone tried it? Most of time automatic methods make me leery, but I have to admit I am pretty impressed with the automatic logging feature built into DAQmx, and was wondering/hoping whether Channel Expansion is the same.

Cheers,

mcduff

[Kevin_Price]

From the links, it appears that "Channel Expansion" (aka multi-device tasks) offers to do most of the dirty work for you.  I'd go ahead and try these automagic methods and assess them.   Feed something like a triangle or sawtooth wave to both devices and look at the data they each capture to evaluate the quality of sync.   

My main experience syncing Delta Sigma devices with "regular" devices came up in an application where I was syncing output signals.  I don't believe there was (or still is?) similar support to automatically sync output tasks across different styles of D/A boards so I had to do it the old fashioned way.  Consequently, I don't really have practical experience with Channel Expansion.   

As I recall, when it was first introduced, the kinds of boards you were allowed to group into a single task was originally much more limited.  Apparently, that support has expanded to be much more flexible and useful over the years.   I doubt the support would have been allowed to go mainstream until they worked out the kinks, so I'll bet you'll be able to use the Channel Expansion feature pretty seamlessly.

Remember, I'm mainly speculating, so give more credence to someone who's actually been there and done that.

-Kevin P