Current Status of Hardware Controls VME-based front end processors for detector control.

1. Slow Controls Upgrade for STARJennie Burns, Undergraduate Student, Department of Physics, Creighton University for the STAR ExperimentThis work was supported by the Office of Science, U.S. Department of Energy. Currently the STAR (Solenoidal Tracker At RHIC) experiment is using specialized VME-based front end processors for its data acquisition and control systems. After years of design work and construction, STAR was assembled at Brookhaven in 1998 but over the last 10 years processor speed has increased and the use of personal computers for the control and monitoring of these experiments is now possible. The system is being revised to replace old hardware with PC's which are less expensive and more easily maintained in order to accommodate new detector subsystems. The original STAR control system is compared with the upgraded system. The architecture and the implementation of upgraded control systems for the Ground Integrity Device (GID) and Time Projection Chamber (TPC) & Forward Time Projection Chamber (FTPC) Gas Systems of the STAR experiment are also presented. Current Status of Hardware Controls • VME-based front end processors for detector control. • Front end cards were housed in VME crates. • EPICS R3.12.4 or R3.13.1 on Sun Ultra-10 workstations running SunOS. • Most workstations open an X-window with MEDM (Motif Editor and Display Manager) displays for the control and monitoring of experiment parameters. • Data for the user interface is received from local Ethernet broadcasts. • 30 MVME 167 and 162 processors running VxWorks 5.2. • VME boards are 10-yr-old dedicated specialized processors with low memory capability. • Some VME boards use program code that is incompatible with newer versions of VxWorks. • Startup files are downloaded over Ethernet from a single Sun host workstation. • Commands can also be entered over a serial line and reboot can be initiated using CANbus controls for the VME crates. • CDEV (Control DEVice) is used to exchange data between the STAR control system and other external systems. • Archived controls data is web accessible. • A limited amount of data is passed to the event stream and to the online database. Upgrade of Hardware Controls • PC-based front end processors for new subsystems. • Existing subsystems which use serial interfaces are being moved to the PC-based system. • VME-based front end processors continue to be used for existing subsystems whose front end electronics is housed in VME crates. • Linux workstations are used for new and upgraded subsystems. • Sun Ultra-10 workstations are being phased out. • Upgrading to new versions of VxWorks is required for compatibility with EPICS R3.14. • VME boards system is being upgraded to Linux compilable VxWorks 5.5. • RTEMS 4.6 is also being evaluated for use as an operating system. • Program code is available locally on the PC processors. Program code for the VME processors is downloaded from a Linux workstation. • Requirements for the new systems: must be backwards compatible, existing software and programming should be retained as much as possible in appropriate settings , and there should be a migration towards current generation of hardware where possible. • Soft IOC’s will provide a model for other various other upgrades of the STAR experiment. Upgraded Systems at STAR • GID (Ground Integrity Device) • Reads current and detects deviations from earth ground. • Entire STAR experiment bases its data and calculations of subatomic particles from the energies running into and out of such devices like the particle tracking system within the experiment, which makes knowing these energies vital in determining the particle’s properties because the entire experiment bases its measurement of current signal strength from the signal’s amplitude with respect to ground. • Measurements of energy deposited in the particle tracking system are used to reconstruct what particles passed through the detector, where they passed, and with what momentum they passed. • Current Monitoring System • For years has been monitored by journal entry periodically throughout the day. Upgraded Monitoring System • GID is located in experiment hall and connected to a PC placed within the Data Acquisition (DAQ) Room by cable. • PC is connected to the local network which makes it possible for the GID readings to be directly monitored and archived in the main controls room. • PC runs EPICS (Experimental Physics and Industrial Control System) which is a framework for building alarms, archives, control panels, displays, etc. • PC also uses a Linux operating system soft-IOC for developing EPICS device support for GID. • Can either use a sequencer/State Notation Language Compiler or Stream Device for data sorting. • Used Stream Device (data sorting software) which easily formats input data. • Properly set up Stream Device for the particular processing of the GID’s stringed data using C programming. • Processed data is sent into MEDM (Motif Editor and Display Manager) installed on same PC for creating the control panel (user interface). • PC connected to local network by Ethernet. • Data is broadcasted and then can be easily accessed and monitored within the main controls room. Figure 1. MEDM display for GID monitoring. • If any problem with the GID, the problem could be better isolated and fixed quickly if the current monitored was constantly archived within a database so that any change could be correlated with other changes in the experiment. Figure 2. Offline archived GID current. • GID upgrade is second upgrade to PC to take place at STAR and 60% upgrade of all slow control hardware is expected to take place by next year. • TPC & FTPC Gas Systems • STAR TPC (Time Projection Chamber) and FTPC (Forward Time Projection Chamber) gas systems regulate a mixture of gases at a certain temperature and pressure to the TPC and FTPC. • Gas systems parameters are archived and purification of the recirculating gas mixture is controlled using a computer data acquisition/control system. • An alarm and interlock system separate from the data acquisition/control system prevents the TPC and FTPC from operating under unsafe conditions. Current Monitoring and Control System • Gas systems located at STAR experiment on RHIC (Relativistic Heavy Ion Collider) stream data into ASCII files which are sent to a processor located in STAR control room. • ASCII files are run through sequencer on VME processor located on platform for reformatting and then sent back to computer in control room for archiving, monitoring, and controlling. Upgraded Monitoring and Control System • Gas monitoring systems save data to Linux processor running EPICS located in STAR control room on which reformatting and processing takes place. • SED (Stream EDitor) is used for reformatting of ASCII files saved by monitoring systems and declaring of new variables for each gas subsystem so that the new system for monitoring and control runs in parallel with existing monitoring and control system. • Reformatted data is then sent into a database using “caput” command and CRON (Command Run ON) is used to pull out data from the database containing the reformatted files every 1 minute. Figure 3. FTPC Gas System formatting of ASCII file and final output of ASCII file data. • Using CRON, the database outputs data to an archive and MEDM on the same STAR control room computer. Figure 4. MEDM displays for TPC and FTPC gas systems monitoring. • New system monitoring/control systems for TPC and FTPC will replace old systems.