NI Labs Discussions
NI FlexRIO Development Tools Discussion
![Ryan_V[DE]](http://forums.ni.com/attachments/ni/170/152606/1/V-ferret.jpg "Ryan_V[DE]"){kind=avatar}
The NI 573x Example Instrument Driver builds on top of the NI FlexRIO instrument Development Library (FIDL). For example, if you look inside the NI 573x Configure Record VI from the NI 573x example instrument driver you'll see that it is really just calling in the FIDL's EngineConfigure VI. That is the host-side code which sends commands down to the FPGA to configure the acquisition engine which is built on the FIDL. If you look at the NI 573x acquisition engine code you can see where and how the values sent by the FIDL's EngineConfigure VI are used to control the number of pre and post trigger samples among other things.
The NI 573x acquisition engine code that comes with the example instrument driver is designed to look at a single channel on the adapter module for triggering, then it stores all of the channels together to DRAM. You'll notice that there is a separate loop for reading/writing DRAM because it runs at a slower "Memory Clock" rate. A FIFO is used to pass data between the triggering/acquisition loop and the DRAM/host-transfer loop because they use different clock domains.
For your applications you can use parts of the FIDL code in the acquisition loop to configure a trigger for each channel and then pass the acquire data for each channel to the DRAM/transfer loop via FIFOs. It's the same basic concept, but you'll need to expand it to trigger for four channels and deal with them individually... and of course modify it to work for the NI 5761 channels rather than the NI 573x 
Regards,
Barron
