The Harp GUI controls the harp device installed before the tagger magnet and has two main functions :
Launching the GUI is very easy once the GUI_launch GUI (see section 4.2) is up. Simply click on the top left popup menu and select 'harp'. A window (Figure 4.2) should shortly pop-up on the screen.
The GUI display 4.2 is basically composed of 3 distinct sections. One for the control of the harp position, one for the display, and one for the scans.
|Target||Position (mm/steps)||Target radiation lengths|
|||2l|The Harp Position Control Panel|
|Retract||The retract button puts the Harp outside of the beam. When clicked, the string ``Retracted Position'' should appear in the message box.|
|A B C D||These buttons put the labeled target into the beam.|
|[1.a]||A lighted target tells that the harp is on that position. A flashing target indicates that the system is in the process of reaching that position.|
|[1.b]||The ``<'' and ``>'' buttons move the Harp 0.5 mm respectively out and into the beam.|
|||2l|The Display Panel|
|[2.a]||The Switches message box displays either :
|[2.b]||The position of the Harp in millimeters (See Table 4.3) . Warning, going into the beam negative position values.|
|2||[2.c]||This button is to be clicked when the system seems not to respond to the commands. It exits as nicely as possible every loop the SNL program could be locked in.|
|[2.d]||This popup-menu will allow you to open the help window or the ``expert'' GUI window (the last one is not documented).|
|||2l|The Scan Panel|
|It contains every controls to perform a beam scan. It is described in the chapter 5.|
|||2l|The Warning Message Panel|
|It will display ``WARNING : It's very likely that the motor is NOT moving !!'' if the Harp switch does not fire when it should. It means that we are probably not where we should be, letting us inferring that the motor is not responding to commands.|
The harp GUI uses the records and hardware detailed in 3.2.3, it runs in the classc3 IOC (see Figure 2.9).
The harp itself is a piece of aluminum about 10 inches long, (Figure 4.3), that supports the radiators and the wires for the scan. This object is moved in and out of the beam by a stepper motor under control of the Harp GUI.
The software for the scans is detailed in chapter 5, the routine that moves the Harp is simple. Anyhow, it provides a mechanism to calibrate the harp when it hits the ``fully retracted'' switch, and a fancy flashing icon when the harp is moving.
The application is under CVS monitoring and is known as
To check it out, type
cvs checkout harp. Then make it by typing
make in the main directory (EPICS compilation variables and flags must
be set, of course).
There are several files of some interest :