System Watchdog Operational Questions

[IanMc]

Sorry if this question was already asked, but I am new to this forum. My team (2022) experienced major problems at the Midwest regional and Wisconsin regional when we were actually running the robot on the field. I have traced the problems to the system watchdog (it is what appears to fit all the problems for our Wisconsin regional). I was wondering exactly how the system watchdog affects the robot? How it can be cleared; as in is it permanent until reboot, or does it clear when new packets start to flow to the FPGA? What are the symptoms of a system watchdog (what the RSL does, what the Drivers Station does, etc.)? Any help on this subject is appreciated so we can try to solve these problems for next year.

Thanks,

Ian

Lead programmer for Team 2022, IRS

[MarkBlack]

Ian,

Take a look at this linked document bellow and let me know if that helps address your questions.

An Overview of FRC Watchdogs

[StephenB]

This document is also pretty good for debugging with the different robot states: FRC Robot Modes / States Explained

[IanMc]

Both of these helped a little, but I still do not see how you clear a system Watchdog or if it clears automatically. (I might have missed something in the articles, sorry if I did).

[MarkBlack]

I'm not sure exactly what you mean by "clear" the watchdog, but hopefully I can clear a couple of things up.  We "feed" the system watchdog by sending the cRIO specially designed TCP packets from the driver station.  If these packets do not reach the cRIO either because we do not have a driver station or the network connection between the driver station and the cRIO is down the system watchdog is "starved."  When the system watchdog is starved the cRIO automatically shuts down all motors and actuators from running.  This will appear as a "NoComms" status on your driver station.  To begin feeding the watchdog again and therefore have accesss to our motors and actuators we simply need to reconnect the network connection between our driver station and cRIO.

The system watchdog was designed as a safety feature and is meant to prevent a run-away robot.

Let us know what other questions you may have!

Cheers,

Mark

NI FIRST Support

[IanMc]

Yes that answers the question, I was using "clear" to mean get out of the watchdog state, which if I understand this correctly, happens once communication between the cRIO and the Drivers Station is regained.

Earlier I was under the impression that you had to reboot to "clear" the watchdog error. Now I see that this interpretation was incorrect.

Thanks for you help,

Ian