VEXNET 2.0 Competition Connection Problems?

So the other day I was in TSA VEX Nationals, and our robot was performing fine with the VexNET 2.0 before the actual competition event itself. Now, when the competition was running, the drive on our robot suddenly died, as well as all the other motors on the bot. We thought something was wrong with our motors, but when we took it out and ran it again, it was working just fine. During the competition, many other robots all with VexNET 2.0 were having the same issue. Some were just relatively lucky.

Is there some kind of problem with the VexNET 2.0 and the Competition connection?

(+filing a complaint)


At worlds in April we ran multiple divisions with no issues. Firmware in the cortex and joystick needs to be V4.22, the radio needs to be on 1.43, was everything up to date? Was that checked during robot inspection? Were there any tech’s keeping an eye on VEXnet performance? How big was this event?

I don’t know if this might be related, but when my kids were at Worlds in April, we noticed they would sometimes lose connection when they went over to the practice fields, which were crammed with kids testing out their robots. We just shrugged off the dropouts as being a result of so many transmitters being so close. We never had any dropouts during competitions or elsewhere. We were running whatever the latest software the Worlds people had loaded into our Cortex for the VexNet 2.0. We’ve had no problems with that software since, either.

The practice fields at worlds are the worse case scenario. Many teams using VEXnet in a relatively small confined space. There were 20 practice fields for HS I think so there could easily be 150 teams all trying to run VEXnet.

As we have discussed before, VEXnet can be configured in three distinct modes, pit mode, download/debug mode and competition mode. The selection is made automatically, for example, connecting to the field control system will cause VEXnet to switch into competition mode. The three modes use different RF channels, the competition channels are different from the pit channels. Download/debug needs more bandwidth and works a little differently. The master and radio firmware plays a part in the channel selection algorithm, however, it’s not an easy task to have hundreds of point to point radio connections all working simultaneously and there was some behind the scenes technology at worlds (which would not be needed at a smaller competition) helping to keep it all running smoothly.

The most important thing to do with VEXnet 2.0 is make sure you are on the latest firmware.

I was also at TSA VEX Nats but had no problems like yours. However When we were doing driver skills it started when it our bot started jerking and stopped. It would occasionally jerk and the ref stopped it. The next robot behind us did the exact same thing. After that… all was well and we had no more problems.

After they switched me to the 2.0s at TSA Nats I seemed to be experiencing a lot more stalling than before, but no connection issues.

I know team 6105c in the middle school division experienced a connection problem durning the 15 sec auton, that caused them to lose to a push bot in head to head.

Just throwing out a guess. Antistatic spray.

Did you switch at the beginning of the tournament or part way through.

They switched everyone when we checked in before the comp

Ya the tiles were probably sprayed with antistatic spray. Vex at most large competitions sprays the fields. This causes many teams to experience more friction when driving.
You should be able to find several threads about this if you Google vex forum antistatic spray.(on phone so it’s hard)

My team (9404) experienced the same problem at nationals in TSA where our autonomous worked perfectly but come time for usercontrol the the robot wouldn’t respond to the joystics commands.

Before and after the competition the robot worked perfectly.The team before and after us had the same problems.

16 months later… Is the 3 mode thing still true with Vexnet 2.0 (white keys).
Texas BEST regional had some connection dropouts.
I’m trying to see if the “game mode dongle” with pins 1,4,6,7 shorted will be any better/different, to see if it helps at South’s BEST regional on Dec3-5.

Yes, still the same.

Do you not use the field control system?

I am from 4221c in Georgia and i went to worlds last year and the vex net caused me many matches because of this same problem. It turned out to be that one of our drive team member’s phone was giving out a wifi signal(hotspot). This same frequency can sometimes be the same with the vex nets causing the vexnet to lose connection and prevent the robot from moving.

Unless the rules have changed in the last few years that is a DQable offense.

Were other teams on your field having similar issues? It sounds unlikely that multiple matches would have had this issue because when you connect you randomly choose an unoccupied frequency. Are you sure it wasn’t an issue on your robot’s end.

Re Texas BEST 2015 Paydirt competition, vexnet dropouts

Thanks, Maybe South’s BEST can try game mode to see if it helps.
No field control system.
BEST is more like : thumbs-up, whistle, basketball clock count down 3 minutes to buzzer.
We keep talking about doing an autonomous period, but haven’t done it yet.