Homing procedure for vertical focusing motors

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This procedure describes the homing of the motors vzm, vyu, and vyd.
At the beginning make sure that not 2 MLLs are mounted in order to avoid collisions during the homing procedure.

1) Switch the controller PI C-848 off.
2) Move vuy and vud by hand to the upper hard limit.
3) Switch the controller PI C-848 on.
4) Execute initPIC848 in a terminal. This initializes the motors.
5) Press HomR in the MEDM screen of vyu. This will home the motor. During homing the MEDM screen shows the message Comm. Failur. This can be cleared by pressing STATUS. After finding the home position of vyu the User/Dial Readback values are -20,700.0138 and Raw 3000002.
6) Move vyu down to User/Dial=-10,000. This is important to avoid the flexural pivot's elastic limit from getting exceeded during homing of the vyd motor.
7) Press HomR in the MEDM screen of vyd. The motor will be homed with the final position User/Dial=-20,700.0138 and Raw=3000002.
8) Finally, home vzm by pressing HomR in the MEDM screen. The home position of vzm is User/Dial=-81,600.0085 and Raw=9600001.