Motors Running Automatically?


I am trying to get my cortex and joystick to “talk” to each other properly. I have downloaded all the new firmware and downloaded/compiled the “ROBOTC Cortex Default.c” code. I have motors plugged into ports 2 & 3 and am using VEXnet keys. When I turn on the cortex and joystick, the motors begin to run automatically after a few seconds and do not respond to the joystick. Any help would be appreciated…


This is a symptom of 3-wire motors plugged in backwards. What kind of motors are you using?

More specifically, it sounds like you might be plugging a 2-wire motor directly into one of the 3-wire ports (2-9). To use a 2-wire motor, you must use a Motor Controller 29 converter cable.

Thanks for your suggestions. I have verified that 3-wire motors are connected to the cortex via motor controller 29’s and that they are not plugged in backwards (I am comparing to the configuration on our other robot w/ cortex which has always worked with no issues).

I have also now noticed that the VEXnet light on the joystick blinks “double red” indicating from the troubleshooting guide that “no VEXnet key is detected.”

Could I have a fundamental problem going on with this particular set of VEXnet keys?

Rachel Zabierek