Synchronising the NI-9775

[KieranW]

Greetings all,

As the title suggests I'm looking to synchronise the NI-9774 module input with an AO card on a cRIO-9030.

I realise this is normally done by extending the FPGA I/O node, but doing this for the AI on the NI-9775 gives me zeroes from the data terminal. None of the module-specific examples seem to show using the I/O nodes for this so I'm not sure if this is even possible?

If not, could someone please suggest a method for synchronising the AI and AO?

Any help would be very appreciated.

[McQuillan]

Hey Kieran,

I couldn't find a reference to the NI-9774 on the NI website, did you mean NI-9775?

As it says in this guide: Synchronizing Analog Input C Series Modules with NI-DAQmx in LabVIEW (Yes this is for DAQmx, but I'm going to refer to the module hardware):

"The Reference Clocked Module (NI 9775) cannot be in record mode when placed in the same task as a Delta Sigma Module" .... "The Reference Clocked Module (NI 9775) cannot be in record mode when placed in the same task as a SAR or Slow Sampled module."

I think this is what is causing you to get erroneous data.

1. Share a master timebase source
2. Start the synchronized acquisition
3. Acquire:
   1. Acquire data from synchronised modules with the same data rate OR
   2. Acquire data from synchronized modules with different data rates

This is a good link to get started

[KieranW]

I did mean the NI- 9775 apologies.

Ah ok, does that mean the AI (9776) and my AO (9262) cannot share an FPGA I/O node?

I'm not sure the latter is SAR or Slow Sampled so I'm not sure why thats the case.

[KieranW · Accepted solution]

I actually found the solution to this;

In order to take data from the 9775 there needs to be a ModX/Start I/O node with a True value wired to it before the I/O data node. This way, it is possible to synchronise it with the AO terminal.