MW6 Target Mover Program
Robert E. West
January 14, 1991
The Target Mover program monitors the power supply MW6W and the beamstop MW7BS once per second. If the status of the power supply changes to OFF or the status of the beamstop changes to IN, the program sets the position of the target MW6TGT so it is out of the beam. When the status of the power supply again indicates it is ON and the status of the beamstop indicates it is OUT, the program sets the position of the target according to bits 0 through 2 of the status reading of the device MWORMODE: Bit 0 is checked first, then bit 1, and finally bit 2. The target is not moved from its out-of-beam position until one of these 3 bits is zero to indicate the desired position. (Note that the positive primary position of the target is also its out-of-beam position.)
This program sets the position of the target MW6TGT when the specified transitions occur in the status readings of the devices MW6W, MW7BS, and MWORMODE. The program does not attempt to maintain the target in any specific position. At their discretion, operators can move the target to any desired position. The program only takes control at the specificed state transitions.
This program is intended to execute on one (and only one) node of the DISNEY cluster. A batch job is executed once every 3 minutes on that node to determine if the program is still executing. If it is not, the batch job restarts the program. Whenever the node reboots, the MW6TGT batch job is started and it then starts the MW6 Target Mover program. Procedures available via the EOPERATOR account allow beamline operations personnel to stop and then restart the MW6TGT process as necessary. The procedure to stop the program first stops the batch job and then stops the program. The procedure to restart the program first checks if the batch job is queued or is executing. If not, it restarts the batch job, which restarts the program.