Loop timing crio vs. roborio.

[tr6scott]

Originally Posted by Ether

One XLS says "Loop Time" and the other says "Lag Time".

Do they mean different things? How was each measured?

Both Measured the same way as the shown in the snipit. Just different programmers from different years did the log heading text.

Both loops used the "Wait for next multiple" labview timer.

I had noticed this behavior when we were doing beta testing, and have not dug into much further. But wait, I forgot I published our 2014 code as part of the beta program, and we did get the logger working in linux os before publishing...

So attached is our 2014 code running on the roborio.

Avg = 49.95124
STD = 0.7159

Just seems like the RT scheduler in the roborio, is not as preemptive in scheduling the loop, as repetitive as the cRIO was.

[Alan Anderson]

The 50 ms data on the cRIO and the roboRIO don't seem significantly different. I'm leaning toward the theory that it's the faster rate that is giving you the unwanted variation in logged times.

Have you measured how long the 20 ms loop is actually taking? Exceeding the expected loop time will give "interesting" results when using a metronome.