The Gem6K drive/controllers rotate clockwise for positive direction moves.
The CMDDIR command allows you to reverse the direction that the controller considers to be the "positive" direction; this also reverses the polarity of the counts from the feedback devices. Thus, using the CMDDIR command, you can reverse the referenced direction of motion without the need to (a) change the connections to the motor and the feedback device, or (b) change the sign of all the motion-related commands in your program.
You must issue a RESET or power cycle the Gem6K drive for the command to take affect.
Once you change the commanded direction polarity, you should swap the end-of-travel limit connections to maintain a positive correlation with the commanded direction.
The CMDDIR command is automatically saved in non-volatile memory.
The CMDDIR command cannot be executed while motion is in progress or while the drive/valve is enabled. For example, you could wait for motion to be complete (indicated when AS bit #1 is a zero) and then use the DRIVE command to disable the appropriate axis before executing the CMDDIR command.