Connection issues?

Yesterday at competition, we had extremely bad connection issues. Of the 11 matches we had, only 2 of them had our robot run completely. Of the remaining 9, in 4 of them, we connected for some parts of the match, then disconnected. Connection usually lasted around 5 or so seconds, and we would remain disconnected for about a minute. At most, we would connect for about 30 seconds. What baffles us even more is that we can easily connect off field, but when the staff starts the match, we lose connection. We even borrowed a field control switch(sorry i don’t know what’s the real name) to test the robot and still worked.

we tried:
-replacing keys(however, i’m not entirely sure both work)
-trying out new joysticks
-moving the key from being covered on 6 sides to 2. (with six sides covered, it was about 1 inch away from metal on one side. With 2 sides covered, it was mounted directly to the arm system[metal] due to the extension cable)
-replacing batteries
-checking our code with other teams
-angling vexnet in the joystick/microcontroller and taping it down. it worked, but eventually after a few matches it stopped working.
-wiggling battery jack

currently our team is fairly confident that the placing of the cortex is a problem(surrounded on all 6 sides, about 5 inches away from each), however, their next belief is to replace the cortex if the previous doesn’t work. Currently we are buying new vexnets that we know for sure work. Any suggestions? We are redesigning for competition in February, so we can take drastic changes.

electronics are aged. Motors vary from new to 4 years old. a battery is 3 years old while another is a bit over a year(we borrowed another team’s battery however). The cortex is about 7 months old. Nearly all the wires are +3 years old, a few are new.

We had this same issue all day. no issues off the field, no issues on our own switch, but as soon as we hit the field, our robot would die in autonomous and then it would take about a minute to reconnect, with about 30 seconds max before disconnecting again, and usually less than 5 seconds. I don’t believe it was a power issue at all, seeing as a charged backup battery was used each time and the robot never died - just the connection.

A couple of Questions:

What programming environment are you using??
What is the Firmware version loaded to the Cortex and Handset?

Also can you do more troubleshooting on the power connection to the Cortex? I was helping a team this Saturday and they had intermittent connectivity issues. It turns out they have a slight connectivity problem with the main battery and the Cortex. It seems the Cortex jack is the issue as we tried several batteries, The team found the problem could be initiated by tapping the top of the Cortex right at the power connector. To remedy it they used some rubber bands to apply some tension to the Battery jack which kept the problem from recurring for the rest of the day.

Cheers Kb

Not entirely sure what your asking(im not savvy in programming), but we use Robot C. Now that i think about it, its version 2.4 (i believe). However, It’s definitely not the newest version.

Woops, i forgot to mention that we tried wiggling the jack to the main battery and 9v battery and we didn’t lose power. However i should mention that our batteries are fairly aged (one 3 years old, one a little over a year year old). However we did borrow another team’s battery just in case and it didn’t make a difference

Do you know if there were Wi-Fi signals in the competition area? VexNet could have potentially accepted interference from these signals (as per law).

So, none of the other teams during the matches you were compeating in had comunication issues? IIRC, there were some issues with the I2C motor encoders causing link issues. Other than that, vexnet keys and then the Cortex itself…

There is another problem I have seen three times so far this year that causes intermittent connection problems. The cable from the towers on the field plugs into a connector on the back of the joystick that uses two plastic tabs to hold the cable in place. The teams I saw having problems had broken off one or both of those tabs which resulted in their tether cable having intermittent connections. The symptom was a dropped connection and various red lights. Sometimes the connect reestablished and some times it didn’t. We were able to diagnose it when the plug just fell out of a joystick the first time I saw it.

So – maybe your problem, maybe not, but it is something else to add to the checklist. For what it’s worth, those plastic tabs are pretty robust – I do not know what kind of gorilla force it would take to break them, but I’ve seen it three times now

Another Very Experienced Person in the VEX community told me that he also seen damaged conductors inside that tether cable port.

What’s happening here is that when the joystick is connected to the field control system the WiFI changes to channel 1. When not connected to the field you are using either channel 6 or 11. An intermittent connection will cause the firmware (presumably) to be changing back and forth, it takes a few seconds each time from what I remember. There was a discussion about this feature back in March.

I have not retested with the latest firmware to see if the behavior is still the same as the firmware we had for worlds but it probably is.

We saw this for the majority of the day yesterday at the competition, I was on the field as a ref. We had tested all of our field towers with a robot the night before they had all worked, and had retested again with four other robots and they had worked… for the majority of teams if they unplugged the backup battery and then recycled the power it would solve their problem.

How many teams do you think had problems? Was it always the same few teams with problems or did everyone experience it? Do you have any idea which firmware these teams were using?

As far as I know it was a fairly wide swath of teams… some of ACME’s teams (12 & 13) and OP Teams (2068), and some others that I cannot recall … for the ACME teams unplugging the backup battery did work, if I remember correctly they said they were on the latest version of firmware. I’ll get one of the team members from 2068 to post their firmware numbers…

By the way, we competed in florida

No other team had connection issues(from what I was told), however the first match was delayed by a whole hour due to issues with the field. All robots in eliminations were functional (except ours)

We tried the field jack after noticing I accidentally stepped on it (woops). However, matches still went smoothly for other teams despite this.

It could be wifi. The administration made an announcement to turn off all broadcasts. However its a middle school, its likely they still broadcast signals even when its closed.

I would assume that the need to unplug the backup battery was caused by being in competition mode, removing main power (or using the power switch) would not cause the cortex to be power cycled which was presumably the necessary action.

Just a little update. I found out that we do in fact have the newest version of Robot C downloaded and it is being used. I also found out that we are also disconnecting at school, however we can remain connected for a much longer period of time. And we know for sure that the school broadcasts wifi. Is there anyway to minimize the interference of other frequencies just in case that is the problem?