HVDP: High Voltage Display Program

Ryan Roth
Pager: (516) 402-4739
Email: rothr@db.erau.edu
This page describes the look and use of the High Voltage Display Program, a program which uses a ROOT-generated GUI to choose information from a Objectivity database and display that information in the form of graphs or histograms.

Contents

  1. Program Description
  2. HV Database Description
  3. The Command Window -- Plotting
  4. The Command Window -- 1D Histogram
  5. The Command Window -- Graph
  6. The Command Window -- 2D Histograms
  7. The Command Window -- Histogram Options
  8. The Canvas Window

Program Description

HVDP is executed by typing HVDP on the command line. This causes the program's two windows to appear. One of these (the smaller one) is the command window, where the user can select what information to plot and what style to present it in. The other window is the canvas window, where the graphics are drawn. By default, the program initially opens a database called "DEMO" upon executing. If another database is desired, the program will accept the first command line argument as the initial database name (i.e., typing 'HVDP -db EMCAL' will cause the program to load the database named EMCAL initally).  The program also accepts a -cf flag, which can specify an initial configuration file, in this manner:  HVDP -cf EXAMPLE1.DPC.  (The program uses configuration files to define the type and style of the multiple plots that can be drawn to the canvas window.)

HVDP 'loads' a database by opening the database and creating a list of all the channels present there which have readbacks. Readbacks are objects which record voltage, current, demand voltage, status, and enable status, together with a timestamp. HVDP organizes the readbacks for the selected channel into a list structure, which is then used to build the appropriate histogram or graph. The user can select one or more of the viable channels from the first list box in the command window.  The selections appear in the second list box, and can be removed from there by clicking their names in the second list box When more than one channel is chosen, the drawing canvas is split into separate, smaller areas known as pads when the "Draw!!" button is pressed.

The actual drawing does not occur until the user clicks the "Draw!!" button, which is located along the bottom of the command window.  The plot types and styles are determined by the current configuration.  The user can change the configuration by loading a configuration file (with a .DPC extension) from the menu bar, or by modifying an existing configuration.   Modifying an existing configuration is simple -- merely select which pad you wish to modify via the slection box at the bottom of the command window.  Then select the type of plot you wish this tab to have via the second selection box.  Then switch to the tab which has the same name as the plot type and modify its parameters there.  If you are making a histogram, you might also modilfy the ranges found on the tab "Histogram Options."  Everytime you change a value, the existing configuration gets updated.  You can save the configuration for later via the "Save Configuration.." option under "File" on the menu bar.

These ROOT-based drawing routines have shown themselves to be sensitive to other window programs, especially Netscape. By this I mean that, if Netscape or another GUI-based program is running when HVDP is executed, then HVDP may not be able to display certain colors (Netscape has a well-known habit of 'eating' the color-maps). In particular, the histograms which use the surface or shading options can look very strange. You can resolve this by closing other GUI applications before executing HVDP.  I have also noted some strangeness involving plots having the "Smooth Curve" option, which may cause them to not be drawn correctly when many plots have this option.

Database Description

HVDP links with an Objectivity database which contains High Voltage information. The program expects the database to have a certain structure; if a database with a different structure is used, it is likely that the program will not be able to plot anything.

The High Voltage databases we use consist of several containers, one for each LeCroy High Voltage Module type that we use in PHENIX. Inside these containers are placed HV module objects. When a module object is created, the database software automatically creates the appropriate number of HV channel objects in the same container. These channel objects are linked to the module object with Objectivity associations. Each channel object has associated with it a HV setpoint object, which contains default information for HV settable variables, such as demand voltage and ramp rates. In a similar way, each HV channel object has associated with it a Readback container, where HV readback objects for that channel will be placed. Whenever the database software receives an instruction to store a readback, a HV readback object is created and placed in that channel's readback container. The Readback containers are named using the following convention: "Readbacks_X", where X is the name of the channel that this readback container is associated with. HVDP accesses these readback containers to find plottable information.

The Command Window -- Plotting

The first tab in the command window provides the user with a way of changing the database being examined and quickly changing which set of channels are selected. After typing in a new database name, pressing 'Enter' in that text field or hitting the 'Load Channels' button will cause the program to examine the new database for plottable channels and list the acceptable ones in the list box. A new channel is selected simply by clicking its name in the list box, which causes it to appear in the second 'draw set' list box.  It is possible to select a channel more than once, and thus see its information in different plots and styles.  There is also a "Print Pad Configuration" button, which prints the current configuration to standard output.  Since, when many channels are selected, the plots can be difficult to see, there has been added an additional 'Maximize' feature.  To get a larger image of a plot, click the corresponding numbered button in the middle of this tab.  This will cause a new canvas to be created, with the correct plot drawn to it by itself.  Note that these buttons can only be pressed immediately after hitting the "Draw!!" button, since to do otherwise would possibly create a larger image of an old plot style.  The program imposes a limit of nine channels that can be plotted at once -- this could be changed, with some effort, but this is not recommended since having more shrinks the plots, making them hard to see and possibily causing program errors.

Here is a picture of the first tab:

First Tab

The Command Window -- 1D Histogram

This tab allows the user to select options for the one-dimensional histograms drawn by pressing the 'Draw Histogram' button. The radio buttons control which aspect of the readbacks are plotted (voltage, current, etc.) The last radio button allows the user to overlay the demand voltage information on top of the voltage information for comparison. The check boxes allow the user to select specific drawing options such as drawing a striaght or smooth line between points, drawing bar-graph style bars, or displaying the information as a lego plot. This tab also contains combo boxes which can change the color of the fill areas and lines drawn, change the marker styles, or use an error bar option.

Here is a picture of the second tab:

Second Tab

A typical Voltage histogram is shown here (default colors -- the canvas has been resized to present it easily here):
 

Default 1D Histogram

The Command Window -- Graph

This tab is very similar to the previous one, except that it controls the options used to draw graphs. Colors and marker styles are selected with combo boxes; what to graph is selected with radio buttons; check boxes select other drawing options. The resulting graph is plotted against time in minutes.

 Here is a picture of the third tab:

Third Tab

A typical Voltage Graph is shown here (default colors-- the canvas has been resized to present it easily here):
 

The Command Window -- 2D Histograms

The 2D histograms drawn with the 'Draw 2D' button are controlled from here. The user can select one of six different 2D plots, and one of 15 different plot styles. Surface and Lego plots are drawn inside a wire-frame cube -- the user can remove all, half or none of this wire-frame by clicking one or both of the check boxes found here.

Here is a picture of the fourth tab:
 

Fourth Tab

Here is a picture of a (default-- the canvas has been resized to present it easily here) Scatter plot:

 
Scatter Plot

Here is a picure of a Lego 3 plot:

 
Lego 3 Plot

The Command Window -- Histogram Options

This window holds the text fields which control the 1D and 2D historgram ranges and bins. The program displays every histogram as centered on its mean value; the values plotted will extend from the (mean-Range) to (mean+Range). Naturally, the ranges for voltages and currents are distinct. For the DEMO database, these values are set to 1000.0 V for voltage ranges and 5000.0 microamps for currents. If you use the command line option to load an alternative database, these values will change to 4.0 V and 50.0 microamps, respectively. However, if you allow the DEMO database to load, and then change the database from tab 1 (Plotting), you may have to alter these text fields to be able to view the histogram. In case you are wondering, the Graph option automatically sizes itself around the data, so you need not provide values for its range. The DEMO database has it's own .DPC file (DEMO.DPC) which holds its enlarged ranges and is automatically loaded if DEMO database is allowed to load.

Note: it is usually a good idea to keep the number of bins in 2D histograms small, because a large number of bins there slow down the program and make the histogram more difficult to read, usually without providing any additional resolution that is helpful.

 Here is a picture of the fifth tab:

Fifth Tab

The Canvas Window

This is the drawing area. It remains blank until one of the three drawing button is clicked. When a button is pressed, the designated channel information is drawn to the canvas. The user can manipulate the objects on the canvas, moving or resizing text boxes, for example. When using Lego or Surface options, the user can rotate the plot by clicking and dragging the wire-frame box. When a new channel is selected in the tab 1 (Plotting) list box, the canvas does not automatically redraw -- the draw button must be pressed again.

Recently, ROOT 2.20.06 was installed on the machines in the PHENIX counting house. When operating/compiled under this version of ROOT, this program has an added feature: Zoomable Axes. This means that the user can use the mouse to focus a Graph or Histogram axis onto a narrower area. This is done by left-clicking the axis, and dragging the mouse to create a zoom-in area. Releasing the mouse button causes the program to recalculate the plot, using the marked area as the new borders. This feature allows the user to quickly adjust the plot to make it more readable. However, zooming-out is more difficult, in that you must extend the marked area past the edge of the plot. It is usually easier just to redraw it in this case, or to adjust the range via 'Histogram Options.'

At the top of the Canvas window is a menu bar. This is the standard menu bar ROOT attaches to a Canvas window. There are several options here, most of which are not very useful to this program's goals. However, there are a few which might prove useful to you.

  1. File -- Under the File option, you can save the canvas as a .gif, .ps, .eps, or even a .root file.
  2. Edit -- You can add notes or clarifications to the graph by selecting the 'Editor' option (Note that, by right-clicking an object in the canvas, you can examine and make changes to its attributes, such as font size, color, etc.). You can also clear the canvas with 'Clear Canvas' (oddly enough).
  3. View -- The 'Color' option lets you see the different colors that the program uses. This is a good place to look if your histograms look strange -- if you don't see 50 different colors -- (number 10 is white) than you probably have another GUI that is eating part of the color map. You can also look at the different marker styles under 'Marker' (HVDP uses 5 of these styles).
  4. Options -- The most useful things here are the ability to turn off and on the the Histogram/Graph Title bar and the Histogram Statistics box with 'Histogram Title' and 'Statistics', respectively.
Unless you want to play with the ROOT Browser option, the Inspect and Classes Menu options are not too useful. The usefulness of the Help option is, of course, debatable.

Here is a picture of the canvas when nine channels have been selected, with various styles:

 Multiple Plots

Here is a picture of an expanded pad:

 Expanded Pad

Here are some links to pictures developed using some 'standard' configurations:

 1D Histograms
 Graphs
 2D Histograms

Follow this link to download the source code file.

Last Modified: 9 June, 1999