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Subsections


The superharp interface window

The automated hall C superharp interface window program allows control of both data acquisition and data analysis. The flow chart of the code is shown on Fig. 2.5. Each superharp device is controlled via EPICS. The signals obtained from a scan are then stored into an ASCII file which serves as an input file for a C++ routine where all the calculations are performed. The main interface window is shown on Fig. 2.6.

Figure 2.5: Flowchart of the hall C superharp interface program.
\begin{figure}\begin{center} \psfig{figure=superharp-flowchart.ps2}\end{center}\end{figure}

Figure 2.6: The hall C superharp interface window.
\begin{figure}\begin{center} \psfig{figure=superharp_interface.ps2,height=6.5in,width=5.5in}\end{center}\end{figure}

In this section, we will review the different menu items that allow users to perform a scan and perform data analysis.


Data Acquisition

The corresponding code is running only on the actual cdaqh1 cluster located in the experimental hall C counting house. Selecting \fbox{Harp $>$\ Scan} launches the MEDM executable routine.

There are two control panels: one allows the user to select the appropriate superharp (Fig. 2.7) and one to perform the scanning process (Fig. 2.8).

Figure 2.7: The hall C superharp selection control panel.
\begin{figure}\begin{center} \psfig{figure=superharpChoicePanel.ps,height=7.2in}\end{center}\end{figure}

Figure 2.8: The hall C superharp scanning control panel.
\begin{figure}\begin{center} \psfig{figure=scan-panel.eps}\end{center}\end{figure}

Before starting any scanning process, verify that you have the correct default parameters as shown in Table 2.1 below.

Table 2.1: The default scan parameters for the hall C superharp system.
Values:    
Acceleration 2000 tr/min  
Velocity 20000 tr/min  
Deceleration 2000 tr/min  
Pre-Gain Amplifier (PGA) 2  
Messages:    
State 1  
Status Declared Zero Point Harp Position  
Input Register 64335  
Analog Digital Converter (ADC) counts 10-30 (background)  
Cmd Readback 129  


If not, then enter the correct value(s) and hit \fbox{return}. Note that the value will not change unless you hit \fbox{\bf return}. The last two digits in the \fbox{Input Register} box may not be the same due to the 10 $\mu$m accuracy of the encoder.

After launching MEDM, click on the red \fbox{SCAN} button to begin the scan. The list below describes the change in several important variables during the scanning process.

  1. \fbox{{\bf State}} changes from 1 to 4.
  2. \fbox{{\bf Status}} indicates Harp is moving, Harp is retracting, and Declared zero harp position during the corresponding motion of the harp. Declared zero harp position indicates that the scan is finished and the harp has returned to its fully retracted rest position.
  3. \fbox{{\bf Velocity}} changes to 30000 tr/min when the harp comes back.
  4. \fbox{{\bf ADC}} registers the number of electrons picked up when a wire crosses the beam.
  5. \fbox{{\bf Cmd Readback}} reads 66 when the harp is moving in the forward direction and 65 in the backward direction.


Data analysis

Although \fbox{\bf harp\_ana\_new} is the main executable, the files \fbox{\bf harp\_ana\_new.tk} and \fbox{\tt bltwish} are both required: \fbox{\bf harp\_ana\_new.tk} contains the graphical routines for the program and is interpreted at run-time through \fbox{\bf bltwish}. \fbox{\bf harp\_ana\_new} contains both C++ and Tcl/Tk codes: \fbox{\bf harp\_ana\_new} is written in C++ and contains most of the calculation routines, and \fbox{\bf harp\_ana\_new.tk} is written in Tk and contains the user interface and graphing routines.

Menu and entry Items

The menu commands and entry items are described in Table 2.2.

Table 2.2: Definition of the menu commands, accelerators and entry items.
Menu Commands and Accelerator
File Reset Ctrl-R Clears all graphs and removes all data.
File Load Ctrl-L Load all data in the current path.
File Save Ctrl-S Saves all data in the current path.
File Print Ctrl-P Prints all graphs to the current printer.
File Quit Ctrl-Q Exits the program.
Harp Options   Calls the configuration dialog.
Harp Scan   Launches the medm scanning routine.
Calculate dP/P0   Calculates $P$ and $\Delta P$ based on the current data.
Calculate Smooth Ctrl-M Filters out background noise in all graphs.
Calculate Unsmooth Ctrl-U Reverses Calculate Smooth.
Calculate Transform Ctrl-T Calculates the Fourier cosine transform
    of the data.
Entry Items
Superharp   Load the selected superharp from the path
    listed in the File Name entry and graphs it
Experiment   Specifies the number of the current experiment.
    The destination for files created by File Save
    is scan_data/Experiment/File Name
File Name   Specifies the location of the harps to be loaded
    or the destination for the files created
    by File Save
Printer   Specifies the current printer


Help and BLM data

The two remaining buttons on the superharp interface window menu bar, \fbox{{\bf BLM data}} and \fbox{{\bf Help}}, allow users to switch to the BLM channels and displays this document (harphelp.ps), respectively.

next up previous contents
Next: Using the Program Up: Superharp Systems Previous: The Superharp Device
Hall-C Staff
2002-11-04