User-defined variables transfer custom FPGA-processed data between an FPGA VI and an RT VI.

Note   On the NI-9145, you can transfer data between the FPGA targets and the real-time targets only by using user-defined variables. Refer to the LabVIEW FPGA Module User Manual for more information about transferring data between the FPGA target and the host on an RT local chassis.

You can add user-defined I/O variables to the block diagrams of FPGA VIs and RT VIs running on the target. Use the variables to communicate between the FPGA on the NI-9145 and host real-time target. All I/O variables are unidirectional, so you must configure the direction of each user-defined I/O variable. Configure the direction as either FPGA to Host or Host to FPGA.

For example, you can acquire analog I/O data and perform an FFT on the data in an FPGA VI. Use an FPGA to Host I/O variable to transfer the processed data to a control loop in an RT VI. Then use a Host to FPGA I/O variable to transfer output data from the RT control loop back to the FPGA for output to the physical I/O channel.

Note   Refer to the LabVIEW User Manual for more information about the user-defined I/O variables.