FPGA interface with NI 9401 and NI 9403

Hi,

I am wondering about the difference between these modules when using with cRIO and FPGA interface.

As far as I think the NI 9401 has its own 2 counter/timer peripheral, so in case of using with cDAQ in can properly work as encoder input or PWN generator. But when used on FPGA all counter/timer logic can be implemented in FPGA so no peripheral is needed and thus I could use NI 9403.

What is the difference between those two modules on bare metal? The cRIO uses SPI communication to communicate between cRIO <-> modules, but what does that mean in the case of NI 9401 and NI 9403. Does NI 9401 have schema like ARM<->FPGA <--NO SPI--> |9401| Isolated buffer <-> protection <-> digital pin?

Does NI 9403 have schema like ARM<->FPGA <-- SPI --> |9403| "some kind of mux which translate SPI to DIO logic" <-> isolated buffer <-> protection <-> digital pin?

Thanks in advance for your reactions 🙂