Emergency question on vexnet

Hi, we have a super-heavy robot with a 8 motor drive and a power splitter

I don’t think the robot is stalling, as the power splitter and the cortex ports lose power all at the same time.

However, after driving around for a few seconds, the robot loses vexnet connection (the remote’s LED and the robot LED blinks red), even with direct connection via the orange USB wire. We’ve tried different remotes, with the same results.

After a few shut-offs and reconnections, the remote does not reconnect to the robot (vexnet blinking red) while the robot has the two solid green LEDs on ROBOT and VEXNET.

I think we had better results with better charged batteries, but I’m not sure

We currently do not have back-up 9V batteries on the cortex

Our competition is tommorow :(, thanks for the help

Get a 9V backup battery. If the problem persists, reply. The 9V battery is fundamental to optimal performance.

When it stalls out it sometimes helps to power cycle the robot and remote. Unless you’re in a match and can’t. :stuck_out_tongue:

I don’t know if this applies to you, but something we discovered a few days ago is that if the key is very loose in the cortex (our’s is, although it’s pretty much new), the starting and stopping can shake the key so it becomes temporarily disconnected, and then it needs to reconnect. We now use some masking tape to hold the key in firmly.

Good luck at your competition and hopefully you get the problems fixed! :slight_smile:


How old are you 7.2V batteries ? It sounds like a battery issue, perhaps the battery connector or connection to the cortex, they are notorious for causing problems after a year or two of use.

We switched the cortex to an older one we had and it seems to work better, except that the connection to the main battery can be loose and become disconnected

Would the cortex (which was newer than the one we just switched to) work if it is connected to a 9v battery?

The point of the 9V battery is to supplement any sudden power dropouts with the primary intent of keeping the VexNet connection live. I think this answers your question as I’m not 100% I know what you’re asking.

Switching cortexes and the problem being slightly alleviated signals a finicky battery lead and cortex battery port, although it could still be a key issue (but seems less likely).

Hope this helps!