[BeardyMentor]

Trouble shooting is very difficult. It usually takes a good understanding of the system, experience with other problems, and knowledge of the history of the system. I have done this for quite a while on a large variety of equipment ranging from military aircraft, industrial automation, CNC machining equipment, 3D printers ranging from $1,000-$2,000,000, among many others. Trying to codify how to do it is always frustrating as it is very difficult to hit all the bases. More so on a machine like an FRC robot where there is very limited experience with this particular situation.

The first step is usually to very clearly define what is happening or not happening. Try to run a function check of everything on the robot. This can reveal problems that are related and possibly give more clues to the cause.

Next write it all down. Our team keeps a binder with our prematch inspection checklists and every single problem we encountered any time we were operating the robot in a mostly completed configuration (from week 5 in build season or so). We have this year made it very granular, down to the level of recording every loose screw and broken zip tie. This has been invaluable in finding and tracking down intermittent problems.

Check the stupid stuff. No, really check the stupid stuff. Did you include all the appropriate libraries in the code? Is your Ethernet cable plugged in all the way? check it again anyway. Did you read the datasheet on how to properly operate the weidmuller connectors? Lightly tug on all the wires, anything pop loose? In my experience, at least 75% of the time it is some thing silly like an unplugged connection, bad crimp, blown fuse. Basically, define the problem, then start checking every part that can possibly contribute to it. Do not assume anything is fool proof or was done right. Even the stuff you did yourself.

Finally, design with the knowledge that everything will break eventually. Do not hope that the relay you tucked underneath the toughbox with 2 cims, an encoder, 5 million feet of wire between you and access to it will survive the whole season. You know it will not because it is the hardest part to access. Keep things neat and easy to access. Nothing sucks more than trying to track down that 5ft long PWM cable as it runs through a rats nest of wire. Remember Murphy's Law; What can go wrong will go wrong. Also, The Addendum to Murphy's Law; Murphy was an optimist.