What is the Logic Behind NI FPGA Modules and Single Cycle Timed Loop?

Issue Details

I am seeing NI-9476 is not supported in SCTL and NI-7856 is supported in SCTL. I would like to know the logic behind SCTL support for the hardware and which factors/ parameters is the decider for SCTL support.

Solution

The question behind hardware support in SCTL is, if the hardware is able to perform the operation within 1 clock cycle or not.

For example, AI and AO takes multiple cycles to execute, so they cannot be used within a SCTL.

For the NI-7856, the DIO ports which can be used in SCTL and the analog ports cannot be used for SCTL.

Regarding the NI-9476, or in general C Series Digital Modules, you have to differentiate between parallel and serial modules.

Parallel modules are fast, but have a low channel count. Serial modules have a higher channel count, but are slower.

The NI-9476 is a serial module, so it cannot execute the operations in one cycle. and therefore is not supported in a SCTL
note: serial modules also cannot be used as for Counter Input / Counter Output in cDAQ / DAQmx mode cRIO.