Labview 2018 & DAQmx synchronings ADC between NI 9234 and NI 9215

[celtjon]

I need to synch data acquisition between multiple devices in a single cDAQ chassis.  We have 1x NI 9234 and 2x NI 9215.  I have managed to synch the 2 NI 9215's using the sample clock of one as a master, however using the same clock to synch the NI 9234 (which can accept external sources) did not work.  The error suggests that the clock source may be invalid.  So, can anyone suggest either a work around or the right way to synch between these 2 devices?

[Kevin_Price · Accepted solution]

The 9234 probably does *not* accept external sample clocks directly.   However, you could probably configure to use the 9234 as the timing master and have both 9215 modules receive their sample clock *from* the 9234. 

This will keep the instants of sampling in sync.  You'll need to understand some further things about filter delay on the 9234 and do a little work to put the *data* in sync.  I was just in this recent thread covering a similar sync topic.

-Kevin P

[mcduff · Accepted solution]

Since you are using cDAQ modules, it would not hurt to try Channel Expansion.

See

https://knowledge.ni.com/KnowledgeArticleDetails?id=kA00Z000000P8XiSAK&l=en-US

and the associated links within.

I think channel expansion works for cDAQ but not so much for PXI. Anyway it is real easy to try.

mcduff

[celtjon]

Thanks for your help.  That seems to work. 🙂

[celtjon]

I'd not used channel expansion previously but that does seem to also work.  Thanks for your help.