Overview of E866 Target Control
08/13/96

Control Hardware

A Stepping Motor (SM) drives the table on which the hydrogen, dueterium and vacuum targets sit. 
 It is controlled by a Step Motor Controller (SMC) which is controlled by an IBM PC through 
software written in Quick Basic.  This equipment is located next to the women's restroom.

In the event that you need to stop the target from moving and the software is not responding, there 
is a switch at the front of the stand on which the computer sits which will turn off the SMC.  

Safety Hardware

In addition to the control hardware, there are several pieces of safety hardware which prevent the 
target from being operated if there is a danger that it will be damaged by the beam.  This is achieved 
in two ways.  

First, by default, the computer will not begin a move until after the end of a spill.  The PDP initiates 
a signal once the spill has ended which is converted to a 100ms pulse by a two gate generator 
(LeCroy 222).  The resulting TTL pulse is converted to an RS 232 signal by a TTL to RS 232 
module and read into the Recieved Data pin of the second serial port on the IBM PC controlling 
the SMC.  

And second, four switches are set up to detect whether or not the target is occupying one of the four 
valid positions corresponding to one of the liquid target vessels, an evacuated vessel or thin air.  If 
the target is not at a valid position, the interlocks will be broken and beam will not be permitted into 
the target area.

Lock Out Procedure

The lock out procedure for the target control system is the standard lock out, tag out procedure.  If 
you need to prevent the target from moving, you should shut off the SMC, lock the switch in the off 
position, and place a tag with the date, the reason why the target was locked off, who you are and 
where you can be reached on the lock.

Moving the Target

The batch file target.bat, located in the c:\bats directory, is a menu driven batch file which is used to 
call the different target control programs.  ESC will take you up one menu level until you reach the 
highest menu, at which point you may choose an option to exit from the program.

Currently, the only available option (save for the uninteresting EXIT) is option 1, Select Target.  As 
you may have already guessed, you will be presented another menu, giving the four available targets 
(H2, vacuum, D2, and air).  Selection of one will run the program MOVE.EXE, located in the 
c:\target\system directory.  MOVE will begin moving the target after it recieves a Good Spill signal 
initiated by the PDP.  When the move is complete, control will be returned to the batch file.

Should it become necessary to stop execution of the program, F9 will exit the program at the 
urrent point of its execution.  If you need the target to stop, F3 will stop the target and terminate 
program execution.