I was unable to reproduce the error that you described. 

What I did to test:

Positioned an RX-28 to center  (firmware version is 23)

Turned torque off (0x18)

Moved the motor by hand

Turned torque on

Registers  0x1E and 0x1F show the new position value and the motor did not jump to the previous position.

Hi Christian,

Below is the answer I got from our tech guy. Let me know how things turn out.

0x1E and 0x1F is the goal position address. If you inputted the max speed there, that means 1023 which is the same as the position value has been written. The position value is 1023 so I believe this is what you are referring to as "jump."

From the information you sent us, it looks as though you are not using our company's controller. If you try testing with another controller and the problem persist, please check your program. Also, if you aren't using our products, we recommend you to do so for full support.

We are assuming there is no error in the program itself, but can you also check whether the max angle degree is set correctly.

If you are having H/W problems, the below may be the cause:

1.     the motor's default position is not located within the max degree range

2.     the power for the motor is not connected to the controller or control board and is connected directly to the motor.directly

As you mentioned in your e-mail, if you suddently enable very high torque, this may also be a cause. If the problem continues, the motor's PCB will damage and will not function properly. It will move at max speed and move to the max angle or go into endless turn.

When first setting your program, make so that the current position is the same as the goal position, even when the torque is enabled. When beginning to control, you must change the goal position.

To add more,

Check whether you have sent a command in an area where the position can not be read.

Dynamixels can be controlled at 300 degrees. (area)

ROBOTIS