Hey all,
I'm running a data acquisition application on a cRIO-9039 (if that shall be of interest) with LabVIEW 19, and appropriate versions of FPGA and RT modules.
Since the last set of measurements, I made some modifications to the FPGA code. I used to be a big fan of local variables, as they, if used properly, may save you some spaghettis. However, of course, I agree local variables are bad in general. What happened now was that local variables, which had been in the code already for the last set of measurements as well (and working correctly), suddenly started acting as constants instead of reading their respective values. Precisely, the local variables would now always yield the initial value of the respective front panel element, instead of the current value. In this case, probing the variable output with another indicator read from the desktop VI shows the initial value, instead of current. Reading the front panel element owning the local variable directly from the desktop VI however gives the correct, actual value.
The most strange thing about this is the sudden change in the behavior of the local variable, that occurred somewhere along the process of modifying the FPGA code.
I got the issue solved by replacing the local variables by the front panel elements directly, which have been partially disconnected before. Any ideas how this may be explained?
A guess from my side: The whole thing happened somewhere when the FPGA started running low on slices. Maybe, by that time, LabVIEW started an optimization process and replaced any front panel elements, which are not modified (or read) within the FPGA VI itself, by constants. Greatly overlooking the fact that the front panel elements were modified by values set in the desktop VI...
Now that I'm done writing this, my own guess seems to make even more sense than before. Still interested in your suggestions on this!
Cheers
