Weird problem with vexnet

Today one of our robots vexnet encountered a weird problem. The vexnet itself is fully functional; however it will NEVER turn off now. For some reason, even if the microcontroller is set to off, if we plug the serial cable for the vexnet in, it automatically turns on. When we try to turn the vexnet off (by turning off the microcontroller), it will not turn off. Has anybody encounter a similar problem? Thanks.

You have your backup battery plugged in, you will need to unplug the backup battery, or it will drain all the power from it.

I assume you are talking about the VEXnet module on the controller on the robot.

First, if you have a simple installation with one controller, I guarantee that the VEXnet will turn off eventually. Have you let it sit with the controller turned off for a few minutes? It doesn’t turn off instantaneously.

Second, do you have a backup battery plugged in? If so, the VEXnet unit won’t turn off until you unplug the backup battery. That’s what the backup battery is for. It’s a good idea to unplug the backup battery when you aren’t using the robot or you are likely to come back to a dead battery.

Let is know how it goes.

i have always had to unplug all power sources to vexnet to make it will turn off even if the microcontroller is off and i don’t know if it is the same for everyone but all other teams i have seen have the same problem because vexnet does NOT have a off switch

Thank you for the fast reply. I have a lot of experience with the vexnet so I know whats normal and whats not. We are not using a backup battery, for the purpose mentioned; I only have the drivers have them in during competition. I know that the vexnet does not turn off until a few seconds after the micro controller AND rc controller is off, however in our case, it will not go out even after 10 minutes of both being off. I know our problem is not normal because what I mentioned earlier:
If we plug in the batteries with the vexnet module and the micro-controller, then plug in the serial cable (the yellow/orange cable from the vexnet), the vexnet automatically turns on regardless whether the microcontroller is set to on or off. This is abnormal because the other vexnet modules will stay off if the microcontroller is set to off.

Wooow, this is very interesting, I did not expect that to happen.
I found the cause of the problem: it is the power expander. I assumed that the battery used for the power expander should not leak into the micro controller, but for this one for some reason it was. I know this because when I turn the robot on, then off, the vexnet will not shut off. However, If I do the same with the power expander’s battery cut off, it shuts off as it should. Could this be a design flaw in the power expander? or do we have a faulty one here?

I laughed when I read this. “Unplug your power expander” was point three in my email, but since you hadn’t mentioned you had one, I deleted it. To completely shut everything down on a controller with VEXnet and a power expander, you have to unplug the backup and power expander batteries and shurt off the controller. That’s how all of our robots configured like this work (that’s 4-5 robots). In the experience of Exothermic Robotics, that is normal behavior.

hmm, thanks for the clarification. Hmm… Our other robots using power expander doesn’t do that :\ interesting.

One thing we found was that we had to unplug the competition switch with disable/enable and driver/autonomous switches from the transmitter to turn off the game light before turning off vexnet/controller/microcontroller before the lights would go off.