Potential new field control fault? VEXU simultaneous controller reboot at Kalahari Classic

@jpearman apologies - channels crossed - skills control disruption issue from other thread - trying to debug that one…

A post was merged into an existing topic: Field controllers disconnecting at skills competition

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I understand the most likely causes, but what is it exactly that triggers the “Radio drops” counter on the V5 Smart Field Controller? I’m guessing that the V5 Smart Field Controller is just polling the V5 brain on the robot and that V5 brain reported a radio drop/disconnect?

The majority of status that the FC system has comes from the controller either directly as internal controller status or status the brain has returned as part of the normal radio communication. One very fundamental piece of information that the controller has is VEXnet radio status, either the controller has a good link to the brain or no link to the brain. If the controller to brain radio link is lost during either the autonomous or driver control periods we record that as a “radio drop” on the team status page. The V5 robot brain will also log a radio disconnect.


Are both “disconnects”? if not, what is difference from FCA that a Radio Drop vs a Brain recording Disconnect?

I think this is confusing teams - is this a symptom of flaw in robot or field control?

When I have discussions with teams it is important they understand what is happening - is it a problem they need to solve? or a problem for EP to fix and in questionable situations, replay match?

It’s the same thing, lost of radio link, I probably used “drop” on the FC team status as the word “disconnect” wouldn’t fit. I don’t remember.

why would it be a flaw in field control ? It’s the same thing we have always had to deal with, radio comms is disrupted for whatever reason, VEXnet radio usually turns from green to red on the robot. changing from the legacy control to new FC system should make no difference.

sometimes, if the radio is buried in the middle of the robot the radio should probably be moved.

the $64k question, over the years the general approach is no replay unless all robots disconnect simultaneously for significant amount of time.


Is it just me or does all robots DCing seem much less important to replay than all from 1 alliance?


certainly you could argue that both alliances were equally inconvenienced.


So one bug I witnessed is that a team had to unplug and plug in to a smart match controller cable several times before we could start the match. Each time they plugged in, their controller would disconnect and go “searching” for the paired robot, but so long as the controller was plugged in, could not find it.

If I understand you correctly, the paired controller likely swapped to a competition channel, and for some reason the robot brain did not… also know to do that? So is this likely a radio issue, a controller issue, or a brain issue? Also, it did eventually work, and could not be replicated.

This was one of several weird events we observed. I had to play whack-a-mole with the Match Control Brain ports. Suddenly one would no longer connect, and I would just move it along to the next port in the quadrant, and the next one, and the next one until it works.

Most likely what happened in the case you are describing is that when the controller was plugged in to the field control it was told to jump to a specific competition radio channel. The controller then did what it was told but could not find an open time slot on that channel. When that happens the controller will remain on the channel in listen mode until a time slot comes available. This was a specific issue at Kalahari because the field brains were not configured correctly at first. Once they realized this, and reconfigured the field controllers this issue went away.


Yes, how might one do this?

When you start a V5 Field Control, in settings there is the option to have the Radio Channel controlled by field activation (meaning TM queues the active match to that field) at that point all the robots change to competition channels. I am assuming this is the configuration Levi is referring to. We have this option set to Disabled since it can confuse teams when the switch over happens.

One key detail I left out of that last description is that the brains used at the Kalahari event were also used at VEX Worlds 2022. Because of the density of competition fields at VEX Worlds, we have a special programming process for the field controllers so that we can tightly control the channel allocations. We updated all the software on the brains but neglected to reset the channel settings. This should be an isolated incident but to answer your question, doing a “Reset all Settings…” on the brain will clear all system settings.

@lacsap is also correct in that the “Radio Channel controlled by Field Activation” should be set to disabled as well. That feature is specific to how we run VEX Worlds and will not benefit competitions that are not using channel specific assignments.


I appreciate that you guys are going to investigate the issue further. I would also like to ask that this event possibly sets a new standard for match replays? The fact that an alliances controllers completely shutting off at the same time (in two consecutive worlds qualifying matches) was merely shrugged off as a robot issue, and not a field control issue, was almost too laughable for me to be upset by losing in such a manner. One would think that an RECF run event as large as Kalahari would give more care into guaranteeing that each team gets a fair shot. What would happen if this same thing occurred in worlds finals?