Any way to synchronize two NI-9234 devices?

[Mark Levine]

I'm pretty sure it cannot be done without having a common analog input and determining the delay by cross correlation but I wouldn't mind to be proven wrong.

1. There are no external clock inputs for the device.

2. Also the timing loop is weird.  In my case for a nominal 100ms acquisition time the loops times jump between 60 and 120 ms with an average over 100 samples of .097.

The NI-9123 is a nice device to remotely locate but it seems to lack the ability to synchronize with other DAQs.

Mark

[Brian_P]

Hi Mark,

Thank you for using the forums.  To answer your question, NI-9234 devices can be synchronized using a cDAQ chassis.  The timebase, sync pulse and start trigger are shared through the back plane of the chassis.  These can be shared automatically by using channel expansion in your DAQmx task.  That is to say that you choose multiple channels on multiple cards and have them all be in the same task.  Here is a great article that explains how to synchronize multiple DSA cards within the same chassis.

For question 2 could you elaborate a little more about your timing loop, are you actually using a timed loop, or a while loop with a timing mechanism to control it?  I am assuming that you are using a Windows based OS, if that is the case it is generally not a good idea to use timed loops because Windows is a non-deministic OS and could actually decrease performance.  Please let me know what you are using and if you could post some sample code that is exhibiting this behaviour that would be great.

Regards,

Brian P.