LHC Gas Control System

1. LHC Gas Control System Stefan Haider EP-TA1-GS

2. Outline • Introduction and working philosophy • Control architecture • Operation • Hierarchies (bubble diagrams) • Information exchange • Who maintains what? • Conclusions ALICE DCS workshop, S.Haider

3. Working philosophy for Gas System Controls • Synthesize commonalities of proposed gas systems.  Modules: Mixer, Purifier… • URD with detailed descriptions of processes • Design document with engineering issues • Produce PLC code and test on real gas-HW • Instantiate modules for a sub-detector • Assembly and commissioning with detector experts ALICE DCS workshop, S.Haider

4. Control architecture Operator workstations Control room CERN / Experiment Ethernet Surface bldg. PBus PBus PBus PBus DI/O DI/O DI/O DI/O DAC DAC DAC DAC ADC ADC ADC ADC PLC CPU I/O modul ProfiBUS CAN-bus Ethernet Plug Device CAN-bus UX P ELMB ELMB ELMB Main PLC CPU I/O modul ProfiBUS Ethernet Ethernet ProfiBUS coupler ProfiBUS Device ProfiBUS ALICE DCS workshop, S.Haider

5. Operation(1/3) - General Aspects • The gas maintenance group will be part of the operation team of an experiment. Like experts of any other sub-system, we shall report about gas to the team leaders. • The Gas Control System of an experiment must be kept independent of other sub-systems as much as possible, because – • the gas systems startup about 3 weeks earlier than other system • and the maintenance crew must find similar environments coming from one experiment to the next • During running periods, Gas Piquets will support the experiments: • 90% of all piquet-interventions at LEP was restarting the gas systems after a power-cut. • Now, the control system will handle this with the “Recover from Power-cut” procedure. • Stability: • Changes of parameters are rare, and reserved for sub-detector gas experts ALICE DCS workshop, S.Haider

6. Operation(2/3) - Operators • DCS shifters will observe the gas systems • warnings and alarms will be reported to a central place,-- ( ok / not ok information ) • in case of “not ok” , panel of the gas system can be opened that show a more detailed fault report • shifter has read-access to all online plots and display panels of all gas system of the experiment • DCS shifter can restart a gas system • after power cuts • after failure of a part of a sub subsystem ALICE DCS workshop, S.Haider

7. Operation(3/3) - Operators • GCS sub-detector expert • has write access to recipes (running parameters) • can start and stop sub-modules of his gas system • GCS gas expert • has access to all changeable parameters of all gas systems in an experiment • Gas System maintenance crew • has limited access to parts of systems that need regular interventions, like O2 cells, etc... ALICE DCS workshop, S.Haider

8. “Reporting/recovery hierarchy” • DCS Shifter sees a problem first, • He calls the sub-detector gas expert, who should be able to resolve most situations. • Only if he can not find a solution (e.g. faulty equipment, etc.) , he will call the “Gas Piquet” from the central Gas Team. ALICE DCS workshop, S.Haider

9. Experiment Control System Shifter Gas Piquet Status Status Sub-Detector Control System CMS PVSS PVSS PVSS HMI HMI HMI GASControl System ATLAS LHCb EV EV EV Shifter, Gas expert, etc Status driver driver driver HMI HMI HMI Sub detector expert ALICE Shifter Shifter, Gas expert, etc ALICE DCS workshop, S.Haider Sub detector expert

10. DCS TPC TRD TOF …. GAS HV LV Sub-sys. Gas TPC TRD TOF TPC PLC TRD PLC TOF PLC CAEN CAEN CAEN TPC gas equipment TRD gas equipment TOF gas equipment Bubbles mean information concentration/display ALICE DCS workshop, S.Haider

11. Independent PVSS systems on individual PC’s AFTER commissioning phase… Commissioning of several gas systems at the same time… Pro: - maintenance of one system easier - common devices easier integrated Con: - downtime,- problem for all, has to be short One PVSS systems for all Gas Systems TPC,TRD,TOF… TPC TOF TRD TOF PLC TRD PLC TPC PLC TPC gas equipment TRD gas equipment TOF gas equipment ALICE DCS workshop, S.Haider

12. Information exchange with the Gas Control System • Gas Control System GCS DCS • Status, alarms, events of each sub-detector • GCS Sub-Detector Control System • Any other information the sub-detector experts may want to access: chamber pressures, main flows, impurities, etc.. • GCS DSS • Under discussion at the moment • Hardwired signals and messages via DIP (or different) are possible • DCS  GCS • None identified yet ! Input from detector experts welcome. ALICE DCS workshop, S.Haider

13. Who creates/maintains what? • Gas group responsible for: • PVSS panels that are necessary to interact with the gas system (main navigation, recipes, download/upload mechanisms, access control, alarm panels etc..) • PLC code. • Sub-detectors are responsible for: • Sub-detector specific PVSS panels: • E.g. correlation of gas data with performance data • E.g. safety actions that turn off HV in case gas is not ready for physics. • Etc.. ALICE DCS workshop, S.Haider

14. Conclusions • We see our work as a service to the experiments, with the aim of producing gas systems that can be maintained by one team for the operational period of LHC • Sub detector experts are in full charge of their Gas System • “Crash-resistant” PLC computers will control the gas system hardware,--- NOT PVSS on PC’s (PVSS = user interaction only) • Displays of gas panels can be installed on any PC at CERN • Design of gas control system is not at all frozen…. Looking forward to user input… ALICE DCS workshop, S.Haider