Working with some kids on EDR robots. What would happen if, when plugging in two drivetrain motors into ports 1 and 10 on the cortex, the wires got plugged in backwards? I’m an electrical noob and am reluctant to run this test in case of explosion/death. Thanks for the help!
Plugging into ports 1 + 10 backwards?
lacsap
#2
Well there are two types of “backwards”, one is when you swap the black and red polarity when plugging into the Cortex, then the motor will run reverse from what you expect it to on the joystick controller. All you need do is rotate the pins in the port such that the red wire is closest to the middle of the Cortex.
The second is if you plug the wrong motor into a port. What happens here is that your joystick controller will operate the wrong side of the robot. All you need to do is swap ports.
In either case, plugging a motor into the wrong port or direction with a two wire motor will not adversely impact the Cortex.
I am assuming you are building the clawbot.
ochoasrobots
#3
Thanks for the response. I am building the clawbot, and I was wondering about the scenario in which the polarity gets swapped. If the polarity gets swapped on the motor controller cable, would that reverse direction as well?
lacsap
#4
Yes, polarity swap at a motor controller would change the direction of rotation of the motor.
If you notice the Clawbot instructions specify changing the polarity for the arm motor and not the claw.
ochoasrobots
#5
Thanks. One more follow up question: would anything happen if one were to swap polarity on the 3-wire motor controller cable that plugs directly into the cortex? I’m assuming that’s different than swapping polarity between the 2-wire cable on the motor controller and the motor cable itself.
callen
#7
Yes, it does work. But you have to swap where the controller connects to the motor, the two-wire connection.
Xenon
#8
It would not make the cortex explode. There is no risk of damage in reversing the polarity.
RougeScaless
#9
So it’s just that when you swap the polarity of the 2-2 wire connection at any place including motor controllers, the motors move in reverse. But when its a 3-3 wire connection, it does not work.
2775Josh
#10
No. It does not work. There are three wires on a motor controller 29. Black (ground) and orange (power) are for power to the motor, but the third (white) is a PWM signal to control the amount of power outputted from the motor.
Reversing the polarity of the connection between a motor controller and the cortex would be trying to power a motor with a PWM signal. The motor controller “knows” which wires do what, and also “knows” it can’t power a motor using PWM, so…nothing happens.
Reversing the polarity on the two-wire connection (from the motor to the motor controller 29) will reverse the direction of the motor, no questions asked.
callen
#11
I was saying the same thing you are. I wasn’t clear enough, though. I should have said “only” or “instead…” This would have been better:
Yes, it does work. But you have to swap only where the controller connects to the motor, the two-wire connection.