At our state tournament this year, in matches throughout the two days I saw many instances of Teams controllers disconnecting from the robots for short periods of time period and many times long periods of the match. For many, the only way to solve the problem was to hit the reset button on the back of the controller. This happened to my sons team in three of their matches in which they lost 2 and won 1. In all cases they were disabled for over 30 seconds. They tried everything to fix the problem, nothing seemed to help. New radio, new wiring, different controller. Radio placed high and in an exposed area. They don’t want this to happen at worlds…
Our hardware is 5 years old, have there been any changes to the hardware that would make purchasing new brains and controllers a solution to these issues?
Any other ideas? The kids are using pros with the eztemplate for programming. Amy known issues with this?
My team had a lot of problems with disconnecting at 2 of our competitions, here’s things we tried beyond what you already mentioned:
Using 2 radios
This doesn’t improve connection as vexnet only ever uses 1 radio at once, but if the main radio gets physically disconnected from the brain it will switch to using the backup one after ~1 second
We got questioned about the legality of this at our comps, but the game manual never explicitly prohibits it so we passed inspection
This didn’t fix it for us but it could still help
Loose ports
Make sure the radio isn’t in a loose port on the brain or it could get physically disconnected when the port gets jossled
You can check this by plugging the radio into the brain then trying to wiggle the plug around, and if the light goes out the port is loose
Of our 3 brains we fund that almost half of the ports were loose on 2 of the brains, and the 3rd one had maybe a quarter loose.
If you can’t get a non-loose port to plug it into, you can try using tape or some other adhesive to hold it into the port (which is legal according to <R7.f>)
This also didn’t fix the problem but it could still help
Battery cable
We were told by the RECF manager at one of our comps that the field controller said there was a “cable error” when we disconnected, and we had already replaced the radio cable multiple times, so he told us to replace the battery cable
This could be causing a problem because a bad battery cable could slightly dip in voltage and make the radio temporarily disconnect
Replacing this seemed to help a little but didn’t fix the problem
Program
Eventually what turned out to be the problem was our program
The program would print 1 line of data onto the controller screen every 60 ms (a little over 16 times per second) and would also rumble the controller when some buttons were pressed
We haven’t disconnected since we turned this off
Side note, we only had disconnect problems on the new smart field controller, and never disconnected in practice with the competition switch. Our theory is that the smart field controller sends extra telemetry data, so the data we were sending was just enough to overload VexNet only during competitions.
smartfield controller is only receiving messages from the controller during driver and auton periods of the match, it does not utilize any VEXnet bandwidth. It sends a couple of small messages over VEXnet when you first connect it before that match starts.
jpearman can correct , but the warning on the V5 Smart Field Controller about cable disconnect relates to the connection between the Smart field controller and the team’s V5 Joystick Controller. It is not about the cable between the V5 Brain and V5 Radio.
Your debugging is commendable, and the conclusion programming error led to resolving an underlying problem.
yeah that was just a guess, I didn’t have any info to back it up other then sending less data to the controller fixed the disconnecting and we didn’t have problems when not using the smart field controller.
If I remember correct the RECF manager said it could be either, and we didn’t have any control over the field wire and had had the problem on different wires anyways, so we changed it just in case. We were basically just grasping at straws at that point because we had already tried everything we could think of (until we thought of the program thing).
In addition to what’s been said already… I’d pay attention to static electricity. Spray your practice fields w/ anti stat spray. Spray a cloth and wipe onto your wheels. Do NOT drag anything under the bot (wire hanging down).
Have seen entire field controllers reset when static was high.
Question about anti static spray, I know that there is a VEX recommended one somewhere (I have the link somewhere), does spraying it actually change the performance of game elements (like triballs, spin up discs), or the robot (I am using odom so this probably won’t be a problem). I guess in other words, does it make the field slick at all, or does it dry normally? I definitely will try anti-static spray on my field as I’ve had some of the issues above before, but just want to know if it affects anything. I’ve also felt the static build up on some of those competition fields, you can feel it and it is crazy.
The anti-static spray recommended for competition use can change how game objects interact with the field tiles. The most notable difference was with mobile goals from In The Zone. On non-sprayed tiles, a 4 motor cortex drive could push a mobile goal with relative ease, but on a sprayed field, the same drive would struggle push it or not be able to move it at all. The legs of the stars from Starstruck also tended stick to the tile when pushed instead of sliding around like they would on a non-sprayed tile.
That being said, with 6 motor V5 drives being the norm, combined with game objects that are lightweight and roll, I don’t expect to see any major difference in performance (if any) with this game.
Thanks to all. Lots of good ideas to try. We will change out all cords and get new battery cords as well. The static spray is a good idea and will try that. In addition, we will look at loose ports.
Any suggestions on best ways to manufacture cables? We use the tool kit provided by VEX. And the kids have built a continuity tester, to make sure each wire has good continuity, but as for the robustness of the cables, IMO they seem to be a bit weak.
We’ve made a good number of cables… and I’ve made tens of thousands of ethernet crimps/punches/cables. Cables look to be robust in my opinion.
It takes a little attention to detail… don’t cut the jacket all the way through. Score it and pull it apart with your fingers the rest of the way. You do NOT want ANY nicks in the individual wire insulation.
Then, test fit the wires. They should be even and fully inserted. The jacket needs to go as far as possible into the connector also. This usually means you have to make initial jacket cut LONG, then trim the wires back a bit at a time until lengths are perfect. (after doing 10 of them you will get better/faster).
Then do a good HARD crimp and you’re done.
If y’all are tearing up wires… probably need to do a better job routing and protecting them. You can also use commercial wire sleeving.