Answered: VEXnet light slow flashing red--Sometimes?

So yesterday I updated to RobotC 3.08 with the provided Worlds master firmware (due to our cortex having the green light issue) installed via RobotC. I did a quick compile and test yesterday and it worked, so I just turned it off and let it be.

Today I actually did some programming, and we had issues with the VEXnet disconnecting at very periodic times (sometimes a few minutes, sometimes a few seconds).

However, towards the end of the day, the Cortex’s VEXnet light would decide to flash a slow red, requiring a power cycle. Usually it would require a couple minutes’ wait after the cycle, but sometimes it would work the first time. But after it disconnected a time or two, it would resume to a slow red. A few times it was a quick red double flash on VEXnet, yet still requiring a power cycle.

It would connect and work sometimes, and other times it wouldn’t even get to the rapid flashing (attempt to connect) before it flashed red.

I don’t know if this is relevant, but once when trying to reinstall the master firmware and once when powering the cortex on, our arm motors would twitch a bit.

What is causing this issue?


I know this is really basic, but did you upgrade the firmware in the joystick?

Yes, I updated joystick, master cpu, and RobotC firmware in that order. The robot does work when it connects; it just doesn’t want to connect after a few times’ disconnect.

After using the VEX upgrade utility for the Worlds firmware and switching our VEXnet keys with keys provided by our teacher, we failed to even disconnect again. I think once it disconnected and reconnected fine, but the red light problem never reoccured. Perhaps something in one of our keys was causing the Cortex to have a short or something?


Please contact for instructions on how to return your VEXnet Keys for testing.