Control System Overview

1. Control System Overview J. Frederick Bartlett Fermilab June 1,1999

2. Outline • Introduction • EPICS Architecture • Channel Access • Scanning • Database Access Levels • Process Variables • Detector Access

3. The DØ Control System • History • Run I - CDAQ • Built at DØ • VMS and Pascal • Platform Independence Decree • Run II - EPICS • Shared with HEP Community • Runs on many platforms • The Standard (Control) Model • Operator Interface (OPI) • Local Area Network (LAN) • Input/Output Controller (IOC)

4. The Standard Model OPI OPI LAN IOC IOC

5. Operating Systems • OPI (Host) • Operating System • UNIX (including Digital UNIX) • Linux • Windows NT • IOC (Front End) • Operating System • VxWorks • Windows NT (Portable CA only) • Linux (Portable CA only) • Platforms • Motorola 68K (MVME-162) • Motorola Power PC (MVME-230x) • Intel (Portable CA only)

6. EPICS Characteristics • Maintained by HEP and astronomy community • Tools and building blocks for a control system • Distributed database • Scalable architecture • OPI’s and IOC’s may be added dynamically • Channel Access (CA) servers and clients • Event driven • Portable CA Server • Written in C++

7. EPICS Characteristics • High performance (records processed per second) • MVME-162 (68K) • >5000 • MVME-230x (Power PC) • >50000 • Extensive collection of applications • Database editors • Display programs • Alarm handler • Archiver • Many more

8. EPICS Channel Access • Channel access provides network transparent access to IOC databases • CA Services • Search - Find a process variable (PV) by name • Get - Get a PV value + optional information • PUT - Change the value of a PV • Add Event - Add a change-of-state callback to a PV

9. EPICS Channel Access • Items returned with a GET • Value • String • Integer (char, short, int, long) • Floating point (float, double) • Enumerated menu string • Optional • Status and severity • Time stamp • Graphics and alarm limits • Control limits • Channel access transforms • numeric formats • native types

10. Asynchronous • Provides a callback mechanism for change of state • Alarms • Value change • Any • Deadband • Archival

11. DB Load Channel Access Ethernet LAN Database Access Scanners IOC Database Record Support Device Support Driver VME EPICS IOC Components

12. DØ Project User Application EPICS File Extractor Ethernet LAN OPI Components Hardware Database CA Interface EPICS .DB File Channel Access Client Channel Access Server

13. Scanning • Periodic - Process at a periodic rate • Standard • 0.1, 0.2, 0.5, 1, 2, 5, 10 seconds • DØ may add other periods • Event - Process when an event is posted • 255 events • Begin run, End run, ... • I/O Event - Process on an external interrupt • Passive - Process only when requested

14. ai rm INP VAL AD00 DA00 ao OUT VAL Database Access Levels - Record • Record • Provides a generic user view of a device + attributes • Simple records may be linked to provide complex behavior

15. Database Access Levels - Record • Record • Monitors • Alarm conditions • Change of value • Transforms • Linear scaling • Table look-up • Sub-field operations (shift and mask)

16. Database Access Levels - Record • Record • Types • Value related • ai and ao - Analog • bi and bo - Boolean • longin and longout - Binary • mbbi and mbbo - Multi-bit fields • stringin and stringout - Character strings • waveform - Block (array) input • calc - General expression evaluation • dfanout - Data replication

17. Database Access Levels - Record • Record • Types • Functional • subroutine - Procedure call • timer - Time delay • fanout - Scan propagation • seq - Sequence ordering • event - Event generation • Complex • pid - Close-loop controller • histogram - Frequency counts • steppermotor - Positioning • scan - Peak finding

18. Database Access Levels - Device • Device • Transforms device-specific properties to record-specific requirements • Types • Bus-specific • VME • MIL-1553B • GPIB • CANBUS • CAMAC

19. Database Access Levels - Device • Device • Types • IOC-internal • Soft (linked to another record) • Symbolic (linked to global object) • Function (call interface) • IOC resource measurement • Detector-specific • Rack monitor • High voltage • SMT sequencer

20. Database Access Levels - Driver • Driver • Required when a device generates interrupts • DØ uses MIL-1553B bus

21. Process Variables • Application programs access process variables (PV) • A PV is associated with an instance of an EPICS record • EPICS records and, therefore, PVs have many fields (properties) that control its behavior • A field name is usually four characters or less and is always upper case

22. Process Variables • D0 PV naming convention • Concatenation of fields bounded by separators • Fields • Detector - i.e. CALN (calorimeter north) • Device - i.e. HV (high voltage channel) • Locator - i.e. • Attribute - i.e. CUR (current) • Field - i.e. HIHI (high alarm limit) • Separators • underscore (_) • slash (/) • dot (.)

23. Process Variables • D0 PV naming convention • Examples • CALN_HV_001/CUR.HIHI • CTL_IOC_11/CPU • MUO_PDT_231/ADC

24. Detector Access • Detector component • Calorimeter • Central, North, South • ICD • Central Fiber Tracker • Barrels and Disks • Central and Forward Preshower • Forward Proton Detector • Luminosity Monitor • Silicon Microstrip Tracker • Silicon Track Trigger (future) • MUON • Central and Forward

25. Detector Access • Accelerator • Gateway link to ACNET system • Data access only • Cryogenics and Gas • Gateway link to DMACS system • Data access only