See documentation here http://emanual.robotis.com/docs/en/dxl/x/xl430-w250/#operating-mode
NOTE : Switching Operating Mode will reset gains(PID, Feedfoward) properly to the selected Operating Mode. The profile generator and limits will also be reset.
Let's say the motor is currently stationary and in Position Control Mode. If I switch operating mode to PWM Control Mode, then Item 2 of the NOTE says that my GOAL PWM will now be the PWM Limit. Wouldn't this cause the motor to start spinning as fast as possible? This would be dangerous for my application.
Thank you for your inquiry.
In order to change the Operating Mode, DYNAMIXEL must be under Torque Off status which cannot activate the core motor.
Even if the operating mode has been set to PWM control mode, in order to move the actuator, you need to manually turn the Torque On and then change the Goal PWM to some other value than the PWM Limit value.
Otherwise, DYNAMIXEL won't rotate by simply changing the Operating Mode.