Optional Counter Interface Unit Type M12 (B870-21) (MP 501/601 Only)
SM 2-39 D255/D256/M281/M282
2. Insert a flathead screwdriver into [A] to release the hook on the inside of the controller
cover [B].
3. Release the hook by opening the right side of the cover, and then remove the cover [A]
by rotating it in the direction of the blue arrow.