Plotting GBT M&C Sampler Logs using an AIPS++ GUI Tool
December 19, 2005
This memo describes the process of plotting data from the GBT M&C log files.
A brief introduction to the concepts involved with using the AIPS++ tools might be useful before getting to the specifics. However, understanding this info is not necessary to simply view data which has been logged. The GBT M/C software writes monitor data logs to a disk in a time-stamped binary format. The data for each device is written to a separate directory. Each record is written periodically at a rate chosen when the logging program is started. A record contains data for the monitor points which have been selected for logging. When a file gets 3600 records, a new file is started. AIPS++ has provided a program called 'gbtlogfiller' which selects a timerange of data for each or all of the receivers or for the weather station. Gbtlogfiller writes the selected data to a local directory in another format, called the AIPS++ table. This table can be loaded into the program GLISH for manipulation and plotting. For these purposes, GLISH can be thought of as a command-line interpereter and programming language. GLISH commands will be used to load a data table, to define vectors containing columns of data from the table, and to plot the vectors. AIPS++ has also provided a GUI interface to the filler which simplifies the selection and plotting of data. This memo describes how to start and operate the GUI; more advanced operation of the filler or plotting routines can be done but is not discussed here.
Starting the System
Log into a Linux workstation. You may wish to define a subdirectory in which to work because the programs you will use write files to the current directory. If so, do a 'cd' to that working directory.
In a terminal window, type the following commands followed by Enter:
Two windows will eventually appear. They are titled:
GBT Log Data: A X-window which is used to select a data source, specify a time range, and to control the software operation.
Pgplot : A second X-window which displays the data plots.
In addition, GLISH is started automatically and GLISH commands can be entered into the original terminal window.
Plotting Data
1. In the GBT Log Data window, do the following steps. Select a Data Source from the list at the left of the window. One or more can be selected by mouse clicks, and deselected the same way. Then specify a Start Time and End Time by clicking on one of the Last Hour, Last 24 Hours, or Last 7 Days buttons, or by typing the times directly into the fields. It is also possible to use one of the time buttons and then to edit the fields. Then edit the Output Table Name if you wish; this is the subdirectory to which the collated data is written.
2.
The Fill button is the "go do it" button. When this is clicked, a new Filler Status window pops up. A gbtlogfiller command is issued, and verbose feedback from the filler is displayed. Wait until you see "Ends successfully" in the Filler Status window and then dismiss the window. The selected data has now been found and written to your local sub-directory.
3.
Note that the Browse, PlotColumns, and Plot Special buttons are now available in the GBT Log Data window. Browse brings up the filled data in the TableBrowser spreadsheet like display. Plot Columns brings up a new window with a list of data columns. Select a column for the x-axis (usually Time), and one or more columns for the y1 (and optionally the y2) axis by clicking on the column names, and then click on the Plot button. The data will be plotted in the pgplot window.
Note: In order to obtain hardcopy plots of the data plots, use the Pgplot File dropdown menu.