ATLAS DCS Gas System Monitoring and fwAtlasGas Component


This page contains information about the handling of information from the gas systems within ATLAS DCS and the fwAtlasGas framework component.

Gas Control System (GCS)

ATLAS has 5 active gas systems, four dedicated to the muon subdetectors CSC, MDT, RPC and TGC and the fifth to the TRT. In addition, there is a module for Flushing of the Inner Detector. The Gas Control System (GCS) is a common software package developped by IT/CO/FE for the control of all LHC experiments' gas systems (23 in total). It uses a set of PLCs for direct control of and communication with hardware devices, while a supervisor PVSS project provides a user interface and configuration options. The Gas Control System has been implemented on the basis of the CERN UNICOS software and is maintained by IT/CO/FE in collaboration with the PH-DT gas group.

Despite being a PVSS project, there is no direct connection between the DCS projects of ATLAS and the Gas Control System, which in this respect is like any other external system. A set of gas system parameters most relevant for subdetectors is published by the GCS via DIP ; subscription to these data is handled in common by the ATLAS information service (IS) projects, which in turn makes these data available to subdetector DCS projects.

PLC Counter and 'Gas System Alive' Watchdog

For each subdetector, the Gas Control System provides a parameter named PlcCounter whose value increases every few seconds. It is the basic means of DCS to check if the gas system is 'alive'.

DIP quality flags

The DIP quality flags are described here.

For the gas system the <dp_name>.quality.uncertain flag is not used. The <dp_name>.quality.bad flag is set on the server side if data is considered not valid.

fwAtlasGas Component

The fwAtlasGas component aims at standardizing and facilitating subdetector handling and display of gas data. It's main parts are

  • A set of functions for data point and data point type creation,
  • A set of functions to configure data point attributes (descriptions, archiving,....)
  • A generic copy mechanism/script for retrieving data from the information service to the subdetector's project
  • FSM types for gas devices and logic objects built from them, plus functions for creating standardized gas FSM trees for each subdetector,
  • Widgets for easy building of gas system schematic views,
  • A set of example panels which can be used 'out of the box' for some of the FSM nodes,
  • Widgets and tools for easy alert configuration and for building alert configuration panels usable by people unfamiliar with PVSS.


The following assumption(s) is/are made and must be met when using the fwAtlasGas component:

  • Projects used for gas system monitoring are distinct for the different sub detectors, i.e. any project contains gas data points of a single subdetector ONLY.
  • ANY gas data points in the local project follow the fwAtlasGas naming convention. This is automatically the case when using the provided functions for creating DPs.
  • Gas channels are numbered consecutively, starting with 1 (required only for the provided FSM panels in fwAtlasMainPanels)

Installation and Setup

To set up fwAtlasGas in a project where it was not installed before, follow the steps listed here, after having read the section Limitations below.

  • Install the component via the JCOP Installation Tool. This will add the libraries fwAtlasGas.ctl, fwAtlasGasFsm.ctl and fwAtlasGasEvent.ctl as well as various panels to the components directory of your project, and will import the gas FSM types (fwAtlasGas_FSMTypes.dpl) as well as some data point types (fwAtlasGas.dpl) for integrity checking and project monitoring. When asked, restart the project, since a library will have been added to the [event] section of your project's config file as part of the install process.
  • Make sure the information service project containing the gas system DIP subscriptions (currently ATLGCSIS2) is seen as a distPeer by the project you install the component in. If this is not the case, edit the [dist] section of the project config file accordingly and restart the project's Distribution Manager.
The next steps are done by executing a set of functions from the library fwAtlasGas.ctl. For your convenience, a setup panel InteractiveSetup.pnl is provided and should be started at this stage. Then

  • Select the subdetector from the drop down list.
  • Create the fwAtlasGas data point types relevant for the selected subdetector, by clicking 'Create/Update Data Point Types'.
  • Create the gas data points relevant for the selected subdetector by clicking 'Create/Add Data points'.
  • Set up some basic DPE configs and dpFuncs for the alive mechanism and integrity checking by clicking 'Configure DPs (base configs)'.
We are now ready to set up the copy mechanism between the IS and the local project. Before doing so it is important to note that while the fwAtlasGas DPTs are common for all subdetectors, not all DPEs are used by all systems and thus should not be copied to avoid overhead. Configuration of which elements are needed is done with the help of so called 'template' DPs template_<dptName> which have been created for each fwAtlasGas data point type during DP creation:

  • In the template_<dptName> data point set the :_original.._userBit1 attribute for elements which must be copied from the IS. You can use the button 'Set Template DP User Bits' in the setup panel as a first attempt to set the userBits correctly, since this however depends on DPE time stamp information on the IS to determine which elements are relevant for a given subdetector the settings should be verified.
  • Add the manager PVSS00Ctrl -num <ManNum> fwAtlasGas/fwAtlasGas_copyGasData.ctl to your PVSS console after choosing which manager number ManNum shall be used and set it to mode always. Set the data point element GasProjectMonitor.CopyScript.ManNum to the manager number you have selected. It will be used for monitoring whether he copy script is running or not.

Congratulations, you have completed the basic setup smile

Alarm Configuration (recommended)

In the setup panel

  • Do a 'Create/Set Bool/Int Alert Configs', this will configure correct alerts on all gas system and gas system module state parameters as well as on quantities related to data validity and quality monitoring.
  • Do a 'Create/Set Sum Alerts' to set up and configure alert reduction in particular for the quality related DPEs.
  • Do a 'Create Float Alert Configs' to create standardized alert configs for all float type quantities. This function sets correct alert classes and texts, but dummy limits, since these are highly subdetector specific.
  • You can use the panel fwAtlasGas/AlertConfigDevices.pnl for activating/deactivating alerts and for configuring the limits of float parameter alerts.

FSM Setup (optional)

Please note that there is no FSM implementation provided currently for IDE.

A standardized GAS FSM tree can be built using the FSM section of the setup panel. To do so,

  • Make sure in DEN that no old gas devices exist in the FSM.
  • Select the parent node for the GAS FSM. By default the gas tree is created below the subdetector infrastructure node <subdet>_INF, but another choice can be taken by selecting 'UserDefined' from the drop down menu 'Parent Node'.
  • Do a 'Instantiate Gas FSM tree'. This creates the tree.
  • Do a'Set FSM Node Labels'.
  • Optional: Do a 'Set FSM Node Panels'. This will configure the FSM to use the panels provided with the component for those devices where such exist.
  • Start the FSM tree and check whether you like the provided panels ...

Note: The FSM panels included in the component all contain a button 'Alert Settings'. Pressing it brings up a panel which shows the alerts currently configured for the device, and allows to modify limits. This however only works if the alert configs/alert classes correspond to the default ones set as described in the previous section.


In the current version of fwAtlasGas,

  • Library functions have been fully validated for the subdetectors CSC, MDT, RPC, TGC, TRT only. They do not fully work for IDE.
  • IDE naming conventions are still under discussion and may change.
  • Functions for setting DP configs (descriptions, archiving, ....) do not include data points which are not assigned to a specific subdetector. This is the case for DPs of type fwAtlasGasEnvironment and fwAtlasGasSource.
  • It is currently not possible to handle which data point elements are to be copied from the IS project separately for active gas and for envelope channels in the case of TGC and TRT. This is due to the fact that a single template_<dptName> data point is used for this purpose, and that active gas and envelop channels/racks have the same data point types, fwAtlasGasChannel and fwAtlasGasRack.
  • The provided FSM types and setup scripts do not include channels, racks etc. dedicated to the TGC and TRT gas envelope system.

Useful Links

Link Description
Gas Control System URD IT/CO/FE's User Requirement Document, providing comprehensive information about the internal GCS implementation
Gas System Parameters published via DIP Reference document by IT/CO/FE listing parameters published via DIP

Major updates:
-- Main.zimmerst - 15 Nov 2008

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Topic revision: r4 - 2008-11-18 - StephanieZimmermann
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