Slow Control SYstem


The Slow Control SYstem (SloCSy) was developed for the RD51 Collaboration Test Beam facilities in order to provide an automated complete system which would control and monitor the high voltage channels of the detectors under test.

It is designed to work with CAEN universal multichannel power supply systems (both SY1527 and SY2527) and provides a user friendly interface for configuring and monitoring the high and low voltage channels. In parallel, tools have been developed in order to provide offline analysis with the data accumulated through the test beam periods.

The relevant internal note for the project can be found here: * RD51-NOTE-2011-011.pdf: Internal Note RD51-NOTE-2011-011

The Slow Control System

Main Interface

The main window of the SLOw Control SYstem is displayed below. Through that, general informations (status, voltage, current) about the high voltage channels are available.

The status of each channel with a color coded background of its name is displayed. The color code used is:

when a channel is turned off
when a channel is turned on
Flashing red
when a channel has tripped


With a right click at each field (name, iMon, vMon) a pop up window with the corresponding history plot of the values will appear. In the following figure the pop up window originated from the name field is displayed. In that plot all information iMon (monitored current), vMon (monitored voltage) and vSet (voltage that have been set) are plotted.


Through the main window access to all the available panels of the program is granted. The buttons on the top of the main window are:

Reload View
manual update of the online monitor of the mainframe (although the refresh rate and the status is 500 ms).
Group Handling
panel that provide the ability to modify channels belonging to a group. More details.
the panel with all the settings of the mainframe and the high voltage channels for each group. More details.
This panel is only for the administrators of the project. Through this the internal data base of the project is accessible. The administrator can start, stop, configure and delete the processes that archive the values (iMon, vMon and vSet). The project is fully optimized and automated and all the prementioned can be done with a simple click only.
panel which is used to export the archived values (iMon, vMon, vSet) of the channels. More details.
Activate group
activates a group that the user selects from the main window.

Group Handling

The group handling panel (see Figure below) simplifies the monitor and control of the high voltage channels when a lot of high voltage cards are connected to the mainframe. Through this panel the user can modify his group only, assign high voltage channels to his group, change the name of the group and change the password of that group. All changes are password protected. When a valid username and password are provided the corresponding group is loaded in the panel and the buttons to make changes are activated.



The ”settings” panel contains all the configurations that can be made for every high voltage channel. In order to change the settings a correct user name and password for the group are required otherwise the buttons ”Set Config” (which saves the desired settings) ”Channel On”, ”Channel Off” (which turns the selected channels on or off) and the buttons for the script are not available.


In detail, someone can select, either one channel at the time or multiple channels from the table at the left. Then, by clicking the appropriate check box, the corresponding field is enabled to be edited.

The available fields are:

  • v0: the desired value for the voltage of the channel (in V).
  • i0: the limit of current (in μA) that a channel can hold for a specific time (trip time) before it trips.
  • rUp: the speed with which a channel reaches the v0 (in V/s).
  • rDwn: the speed with which a channel drops to 0 (in V/s).
  • tripTime: the maximum time (in ms) that a channel is allowed to stay overcurrent (having current above i0).
  • Alias: a custom name that one can set in order to be more easy to recognize the channel (maximum 6 characters).
  • vMax: the maximum allowed voltage (v0) that the user can give to a channel (protection mean for the channel).

There is also another way to configure the channels, is to load a script with the desired configurations for the channels. The configurations as well as the appropriate channels made from the script are shown in the box at the right of the panel.

By clicking ”Set Config” any of the prementioned values used or the values loaded with the script, are set to the selected channels. On the table on the left, read-back settings that are currently stored on the mainframe for each channel are shown. After any change occurs by the user the table is refreshed automatically. This feature gives the opportunity to crosscheck the values the user applied applied.

A logbook is kept on the hard disk of the PC under the name logger.txt . Any change in the settings that any user makes are recorded in detailed here.


In this panel, a channel or multiple channels can be selected and the archived data are exported. From the top right and bottom boxes the desired time period can be selected. After this the user can select between two different structures about the time stamps of the values for the files. In the folder name field the user can set the desired name that the created folder will have. The folder is created under C:/ directory. In that folder the ”txt” files are created. The desired val- ues for the exportation can be selected (iMon, vMon, vSet or all of them) by the appropriate buttons. The name of the file has the following format: (i.e. iMon.R11Mesh.11.05.05.txt) where valueType is iMon, vMon or vSet, channel is either the alias name of the channel (if one exists) or the position of the channel in the mainframe (i.e. board02.channel010 is the channel number 11 of the board that is placed in slot number 2 of the mainframe) and exportationDate is the date that the user creates the specific file in the form:


Each file has first three lines with general information, starting with ”#”. The first line contains the date of the exportation (in the form:, the second the channel and the third the exportation range (in the form: hh:mm:ss). After that depending on the user selection we have:

  • Unix Time: UT milliseconds Value, where UT stands for the Unix time of the value (defined as the number of seconds elapsed since midnight Coordinated Universal Time (UTC) of January 1, 1970, not counting leap seconds) and the Value is in V for vMon and vSet and μA for the iMon.

  • GMT Time: year month day hours minutes seconds milliseconds Value where the Value is in V for vMon and vSet and μA for the iMon.

Offline Data Analysis

The files produced during the ”export” procedure described before, can be used for more detailed offline analysis. The analysis can easily be done using any data analysis framework the user wants. However scripts for ROOT and Gnuplot are available here.

Gnuplot Script


Plot of the high voltage scan of a detector during a test beam. On the same Figure the instantaneous high voltage, the set high voltage and the monitor of current of a channel are plotted. The voltages correspond to the left axis and the current to the right. This plot was produced with Gnuplot.

The script for producing plots like that among with instructions and an example are available here.

ROOT Script


An example script written in ROOT gives the user the ability to have two kinds of plots and also to save the exported data in a root file well organized and ready for further statistical analysis. In figure above, two plots of the operation status of the high voltage of a channel during several days is shown. The bottom plot shows the current (in μA) versus time and the top plot shows the voltage, both monitored and set (in volts) versus time.

The script for producing plots like that among with instructions and an example are available here.

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