EPICS
Encyclopedia
The Experimental Physics and Industrial Control System (EPICS) is a software environment used to develop and implement distributed control system
Distributed control system
A distributed control system refers to a control system usually of a manufacturing system, process or any kind of dynamic system, in which the controller elements are not central in location but are distributed throughout the system with each component sub-system controlled by one or more...

s to operate devices such as particle accelerator
Particle accelerator
A particle accelerator is a device that uses electromagnetic fields to propel charged particles to high speeds and to contain them in well-defined beams. An ordinary CRT television set is a simple form of accelerator. There are two basic types: electrostatic and oscillating field accelerators.In...

s, telescope
Telescope
A telescope is an instrument that aids in the observation of remote objects by collecting electromagnetic radiation . The first known practical telescopes were invented in the Netherlands at the beginning of the 1600s , using glass lenses...

s and other large experiment
Experiment
An experiment is a methodical procedure carried out with the goal of verifying, falsifying, or establishing the validity of a hypothesis. Experiments vary greatly in their goal and scale, but always rely on repeatable procedure and logical analysis of the results...

s. EPICS also provides SCADA
SCADA
SCADA generally refers to industrial control systems : computer systems that monitor and control industrial, infrastructure, or facility-based processes, as described below:...

 capabilities. The tool is designed to help develop systems which often feature large numbers of networked computers
Computer network
A computer network, often simply referred to as a network, is a collection of hardware components and computers interconnected by communication channels that allow sharing of resources and information....

 providing control and feedback.

EPICS uses client/server and publish/subscribe
Publish/subscribe
Publish–subscribe is a messaging pattern where senders of messages, called publishers, do not program the messages to be sent directly to specific receivers, called subscribers. Published messages are characterized into classes, without knowledge of what, if any, subscribers there may be...

 techniques to communicate between the various computers. One set of computers (the servers or input/output
Input/output
In computing, input/output, or I/O, refers to the communication between an information processing system , and the outside world, possibly a human, or another information processing system. Inputs are the signals or data received by the system, and outputs are the signals or data sent from it...

 controllers), collect experiment and control data in real-time using the measurement instruments attached to it. This information is given to another set of computers (the clients) using the Channel Access (CA) network protocol. CA is a high bandwidth networking protocol, which is well suited to soft real-time applications such as scientific experiments.

Look and feel

EPICS interfaces to the real world with IOCs (Input Output Controllers) . These are either stock-standard PCs or VME
VMEbus
VMEbus is a computer bus standard, originally developed for the Motorola 68000 line of CPUs, but later widely used for many applications and standardized by the IEC as ANSI/IEEE 1014-1987. It is physically based on Eurocard sizes, mechanicals and connectors , but uses its own signalling system,...

 standard embedded system
Embedded system
An embedded system is a computer system designed for specific control functions within a larger system. often with real-time computing constraints. It is embedded as part of a complete device often including hardware and mechanical parts. By contrast, a general-purpose computer, such as a personal...

 processors that manage a variety of "plug and play" modules (GPIB, RS-232
RS-232
In telecommunications, RS-232 is the traditional name for a series of standards for serial binary single-ended data and control signals connecting between a DTE and a DCE . It is commonly used in computer serial ports...

, IP Carrier etc.) which interface to control system instruments (oscilloscope
Oscilloscope
An oscilloscope is a type of electronic test instrument that allows observation of constantly varying signal voltages, usually as a two-dimensional graph of one or more electrical potential differences using the vertical or 'Y' axis, plotted as a function of time,...

s, network analyzer
Network analyzer
Network analyzer may mean:* Packet analyzer, used on a computer data network* Network analyzer , a type of electronic test equipment...

s) and devices (motors, thermocouple
Thermocouple
A thermocouple is a device consisting of two different conductors that produce a voltage proportional to a temperature difference between either end of the pair of conductors. Thermocouples are a widely used type of temperature sensor for measurement and control and can also be used to convert a...

s, switches, etc.). Some instruments also can come with EPICS already embedded within them, like certain Oscilloscopes . The IOC holds and runs a database of 'records' which represent either devices or aspects of the devices to be controlled. IOC software used for hard-real-time normally use RTEMS
RTEMS
RTEMS is a free open source real-time operating system designed for embedded systems....

 or VxWorks
VxWorks
VxWorks is a real-time operating system developed as proprietary software by Wind River Systems of Alameda, California, USA. First released in 1987, VxWorks is designed for use in embedded systems.- History :...

, though work has been ongoing in porting to other systems. Soft real-time IOC software sometimes runs on Linux
Linux
Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...

 or MS-Windows based machines.

Other computers on the network can interact with the IOC via the concept of channels. Take, for example a particle accelerator with shutters between sectors. There would typically be several channels corresponding to a shutter: an output channel to activate shutter motion, an input channel to see the status of the shutter (e.g. shut, open, moving, etc.), and probably some additional analog input channels representing temperatures and pressures on each side of the shutter. Channel names are typically in the form EQUIPMENT:SIGNALNAME (e.g. ACCELERATOR_RING:TEMP_PROBE_4, although they can be much less verbose to save time).

Most operations are driven directly from a standalone GUI
Gui
Gui or guee is a generic term to refer to grilled dishes in Korean cuisine. These most commonly have meat or fish as their primary ingredient, but may in some cases also comprise grilled vegetables or other vegetarian ingredients. The term derives from the verb, "gupda" in Korean, which literally...

 package such as EDM (extensible display manager) or MEDM (Motif
Motif (widget toolkit)
In computing, Motif refers to both a graphical user interface specification and the widget toolkit for building applications that follow that specification under the X Window System on Unix and other POSIX-compliant systems. It emerged in the 1980s as Unix workstations were on the rise, as a...

/EDM). These allow creation of GUI screens with dials, gauges, text boxes, simple animations, etc. Newer control systems and
GUI interfaces such as CSS/BOY are being investigated.

However it is not just GUI software which can interact with EPICS: any software which can speak the CA protocol can get and put values of records. For example on the EPICS website there are several extension packages which allow CA support in things like MATLAB
MATLAB
MATLAB is a numerical computing environment and fourth-generation programming language. Developed by MathWorks, MATLAB allows matrix manipulations, plotting of functions and data, implementation of algorithms, creation of user interfaces, and interfacing with programs written in other languages,...

, LabVIEW
LabVIEW
LabVIEW is a system design platform and development environment for a visual programming language from National Instruments. LabVIEW provides engineers and scientists with the tools needed to create and deploy measurement and control systems.The graphical language is named "G"...

, Perl
Perl
Perl is a high-level, general-purpose, interpreted, dynamic programming language. Perl was originally developed by Larry Wall in 1987 as a general-purpose Unix scripting language to make report processing easier. Since then, it has undergone many changes and revisions and become widely popular...

, Python
Python (programming language)
Python is a general-purpose, high-level programming language whose design philosophy emphasizes code readability. Python claims to "[combine] remarkable power with very clear syntax", and its standard library is large and comprehensive...

, Tcl
Tcl
Tcl is a scripting language created by John Ousterhout. Originally "born out of frustration", according to the author, with programmers devising their own languages intended to be embedded into applications, Tcl gained acceptance on its own...

, ActiveX, etc. Hence it is easy to do things like make scripts which can activate EPICS controlled equipment.

Record types

There are different types of records available in EPICS. Here are some common types. Note that in addition to the other records not mentioned here, it is possible to create your own record type to interact with a device.

Each record has various fields in it, which are used for various tasks.
AI and AO Analog Input and Output records can obviously store an analog value, and are typically used for things like set-points, temperatures, pressure, flow rates, etc. A limited amount of conversion to and from raw device data is available natively in the record (typically scaling and offsetting, but not advanced conversion like two's complement or logarithmic).
BI and BO Binary Input and Output records are generally used for commands and statuses to and from equipment.
Calc and Calcout These two records can access other records and perform a calculation based on their values. (E.g. calculate the efficiency of a motor by a function of the current and voltage input and output, and converting to a percentage for the operator to read).
Stepper Motor Control of a stepper motor. Allows settings of things like accelerations and velocities, as well as position.

Record processing

Records in EPICS must have a designated scan time, otherwise they are automatically set as passive. A passive record will never process (unless its PROC field is written to). Mostly records are set to process on a periodic scan (such every 0.1 second).

Alternately records may be set to process only on events.

Facilities using EPICS

A partial list of facilities using EPICS:
  • Australia
    • Australian Synchrotron
      Australian Synchrotron
      The Australian Synchrotron is a 3 GeV synchrotron radiation facility built in Melbourne, Victoria and opened on 31 July 2007.The circular building was designed by Architectus in conjunction with Thiess, while the lattice design was performed substantially by Professor John Boldeman.The Synchrotron...

    • ANTARES - Australian Nuclear Science and Technology Organisation
    • ASKAP (Australian Square Kilometre Array Pathfinder)
      Australian Square Kilometre Array Pathfinder
      The Australian Square Kilometre Array Pathfinder, or ASKAP, is CSIRO’s new radio telescope currently under construction at the Murchison Radio-astronomy Observatory in Mid West region of Western Australia...

       - CSIRO
    • Heavy Ion Accelerator at the Australian National University
      Australian National University
      The Australian National University is a teaching and research university located in the Australian capital, Canberra.As of 2009, the ANU employs 3,945 administrative staff who teach approximately 10,000 undergraduates, and 7,500 postgraduate students...

  • Asia
    • KSTAR
      KSTAR
      The KSTAR, or Korea Superconducting Tokamak Advanced Research is a magnetic fusion device being built at the National Fusion Research Institute in Daejon, South Korea. It is intended to study aspects of magnetic fusion energy which will be pertinent to the ITER fusion project as part of that...

       - Korea Superconducting Tokamak Advanced Research (Republic of Korea)
    • J-PARC
      J-PARC
      J-PARC is a high intensity proton accelerator facility. It is a joint project between KEK and JAEA and is located at the Tokai campus of JAEA. J-PARC aims for the frontier in materials and life sciences, and nuclear and particle physics...

       - Joint Facility for High Intensity Proton Accelerators (Japan
      Japan
      Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

      )
    • RIBF - RIKEN RI Beam Factory Project (Japan
      Japan
      Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

      )
    • BSRF - Beijing Synchrotron Radiation Laboratory (China
      China
      Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...

      )
  • Europe
    • Berliner Elektronenspeicherring-Gesellschaft für Synchrotronstrahlung (BESSY II)
      BESSY
      The Berliner Elektronenspeicherring-Gesellschaft für Synchrotronstrahlung m. b. H. , abbreviated BESSY, is a research establishment in the Adlershof district of Berlin. Founded on 5 March 1979, it currently operates Germany's only 3rd generation synchrotron radiation facility, BESSY II...

       - Helmholtz-Zentrum Berlin
      Helmholtz-Zentrum Berlin
      The Helmholtz-Zentrum Berlin for Materials and Energy is a research centre and part of the Helmholtz Association of German Research Centres. The institute carries out research into the structure and dynamics of novel materials and also investigates solar cell technology.Several large scale...

       (Germany
      Germany
      Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

      )
    • Deutsches Elektronen Synchrotron (DESY)
      DESY
      The DESY is the biggest German research center for particle physics, with sites in Hamburg and Zeuthen....

       (Germany
      Germany
      Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

      )
    • Diamond Light Source
      Diamond Light Source
      Diamond Light Source is the UK's national synchrotron science facility in Oxfordshire, United Kingdom. Its purpose is to produce intense beams of light whose special characteristics are useful in many areas of scientific research...

       - Rutherford Appleton Laboratory
      Rutherford Appleton Laboratory
      The Rutherford Appleton Laboratory is one of the national scientific research laboratories in the UK operated by the Science and Technology Facilities Council . It is located on the Harwell Science and Innovation Campus at Chilton near Didcot in Oxfordshire, United Kingdom...

       (England
      England
      England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

      )
    • International Thermonuclear Experimental Reactor (ITER)
      ITER
      ITER is an international nuclear fusion research and engineering project, which is currently building the world's largest and most advanced experimental tokamak nuclear fusion reactor at Cadarache in the south of France...

       (France
      France
      The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

      )
    • Laboratori Nazionali di Legnaro (Italy
      Italy
      Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...

      )
    • Swiss Light Source
      Swiss Light Source
      The Swiss Light Source is a synchrotron located at the Paul Scherrer Institute in Switzerland for producing electromagnetic radiation of high brightness...

       - Paul Scherrer Institut (Switzerland
      Switzerland
      Switzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....

      )
    • GSI/FAIR - (Germany
      Germany
      Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

      )
    • IFMIF - International Fusion Materials Irradiation Facility
      International Fusion Materials Irradiation Facility
      The International Fusion Material Irradiation Facility, also known as IFMIF, is an international scientific research program designed to test materials for suitability for use in a fusion reactor...

       (Japan, European Union, United States, and Russia)

  • North America
    • Gemini Observatory
      Gemini Observatory
      The Gemini Observatory is an astronomical observatory consisting of two telescopes at sites in Hawai‘i and Chile. Together, the twin Gemini telescopes provide almost complete coverage of both the northern and southern skies...

       (United States
      United States
      The United States of America is a federal constitutional republic comprising fifty states and a federal district...

      )
    • Advanced Light Source
      Advanced Light Source
      The Advanced Light Source at Lawrence Berkeley National Laboratory in Berkeley, California is a synchrotron light source. Built from 1987 to 1993, it currently employs 210 scientists and staff. Part of the building in which it is housed was completed in 1942 for a 4.67 m cyclotron, designed by...

       - Lawrence Berkeley National Laboratory
      Lawrence Berkeley National Laboratory
      The Lawrence Berkeley National Laboratory , is a U.S. Department of Energy national laboratory conducting unclassified scientific research. It is located on the grounds of the University of California, Berkeley, in the Berkeley Hills above the central campus...

       (United States
      United States
      The United States of America is a federal constitutional republic comprising fifty states and a federal district...

      )
    • Advanced Photon Source
      Advanced Photon Source
      The Advanced Photon Source at Argonne National Laboratory is a national synchrotron-radiation light source research facility funded by the United States Department of Energy Office of Science...

       - Argonne National Laboratory
      Argonne National Laboratory
      Argonne National Laboratory is the first science and engineering research national laboratory in the United States, receiving this designation on July 1, 1946. It is the largest national laboratory by size and scope in the Midwest...

       (United States
      United States
      The United States of America is a federal constitutional republic comprising fifty states and a federal district...

      )
    • Canadian Light Source Synchrotron
      Canadian Light Source Synchrotron
      The Canadian Light Source is a third-generation 2.9 GeV synchrotron located in Saskatoon, Saskatchewan, Canada. It opened on October 22, 2004 after three years of construction and cost C$173.5 million. One of forty-two such facilities in the world, it occupies a footprint the size of a football...

       - University of Saskatchewan
      University of Saskatchewan
      The University of Saskatchewan is a Canadian public research university, founded in 1907, and located on the east side of the South Saskatchewan River in Saskatoon, Saskatchewan, Canada. An "Act to establish and incorporate a University for the Province of Saskatchewan" was passed by the...

       (Canada
      Canada
      Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

      )
    • FNAL - Fermi National Accelerator Laboratory (United States
      United States
      The United States of America is a federal constitutional republic comprising fifty states and a federal district...

      )
    • W. M. Keck Observatory (United States
      United States
      The United States of America is a federal constitutional republic comprising fifty states and a federal district...

      )
    • Laser Interferometer Gravitational-Wave Observatory (LIGO)
      LIGO
      LIGO, which stands for the Laser Interferometer Gravitational-Wave Observatory, is a large-scale physics experiment aiming to directly detect gravitational waves. Cofounded in 1992 by Kip Thorne and Ronald Drever of Caltech and Rainer Weiss of MIT, LIGO is a joint project between scientists at MIT,...

       (United States
      United States
      The United States of America is a federal constitutional republic comprising fifty states and a federal district...

      )
    • Los Alamos Neutron Science Center
      Los Alamos Neutron Science Center
      The Los Alamos Neutron Science Center , formerly known as the Los Alamos Meson Physics Facility is one of the world's most powerful linear accelerators. It is located in Los Alamos National Laboratory in New Mexico in Technical Area 53 . It was the most powerful linear accelerator in the world...

       - Los Alamos National Laboratory
      Los Alamos National Laboratory
      Los Alamos National Laboratory is a United States Department of Energy national laboratory, managed and operated by Los Alamos National Security , located in Los Alamos, New Mexico...

       (United States
      United States
      The United States of America is a federal constitutional republic comprising fifty states and a federal district...

      )
    • National Superconducting Cyclotron Laboratory
      National Superconducting Cyclotron Laboratory
      National Superconducting Cyclotron Laboratory is located on the campus of Michigan State University and is the leading rare isotope research facility in the United States...

       - Michigan State University
      Michigan State University
      Michigan State University is a public research university in East Lansing, Michigan, USA. Founded in 1855, it was the pioneer land-grant institution and served as a model for future land-grant colleges in the United States under the 1862 Morrill Act.MSU pioneered the studies of packaging,...

       (United States
      United States
      The United States of America is a federal constitutional republic comprising fifty states and a federal district...

      )
    • National Synchrotron Light Source
      National Synchrotron Light Source
      The National Synchrotron Light Source at Brookhaven National Laboratory in Upton, New York is a national user research facility funded by the U.S. Department of Energy...

       - Brookhaven National Laboratory
      Brookhaven National Laboratory
      Brookhaven National Laboratory , is a United States national laboratory located in Upton, New York on Long Island, and was formally established in 1947 at the site of Camp Upton, a former U.S. Army base...

       (United States
      United States
      The United States of America is a federal constitutional republic comprising fifty states and a federal district...

      )
    • Spallation Neutron Source
      Spallation Neutron Source
      The Spallation Neutron Source is an accelerator-based neutron source facility that provides the most intense pulsed neutron beams in the world for scientific research and industrial development...

       - Oak Ridge National Laboratory
      Oak Ridge National Laboratory
      Oak Ridge National Laboratory is a multiprogram science and technology national laboratory managed for the United States Department of Energy by UT-Battelle. ORNL is the DOE's largest science and energy laboratory. ORNL is located in Oak Ridge, Tennessee, near Knoxville...

       (United States
      United States
      The United States of America is a federal constitutional republic comprising fifty states and a federal district...

      )
    • Stanford Synchrotron Radiation Laboratory
      Stanford Synchrotron Radiation Laboratory
      The Stanford Synchrotron Radiation Lightsource , a division of SLAC National Accelerator Laboratory, is operated by Stanford University for the Department of Energy...

       - Stanford University
      Stanford University
      The Leland Stanford Junior University, commonly referred to as Stanford University or Stanford, is a private research university on an campus located near Palo Alto, California. It is situated in the northwestern Santa Clara Valley on the San Francisco Peninsula, approximately northwest of San...

       (United States
      United States
      The United States of America is a federal constitutional republic comprising fifty states and a federal district...

      )
    • Linac Coherent Light Source - SLAC National Accelerator Laboratory
      SLAC National Accelerator Laboratory
      The SLAC National Accelerator Laboratory, originally named Stanford Linear Accelerator Center, is a United States Department of Energy National Laboratory operated by Stanford University under the programmatic direction of the U.S...

       (United States
      United States
      The United States of America is a federal constitutional republic comprising fifty states and a federal district...

      )
    • TJNAF - Thomas Jefferson National Accelerator Facility
      Thomas Jefferson National Accelerator Facility
      Thomas Jefferson National Accelerator Facility , commonly called Jefferson Lab or JLab, is a U.S. national laboratory located in Newport News, Virginia. Since June 1, 2006, it has been operated by Jefferson Science Associates, LLC, a joint venture between Southeastern Universities Research...

       (United States
      United States
      The United States of America is a federal constitutional republic comprising fifty states and a federal district...

      )
    • TRIUMF
      TRIUMF
      TRIUMF is Canada’s national laboratory for particle and nuclear physics. Its headquarters are located on the south campus of the University of British Columbia in Vancouver, British Columbia. TRIUMF houses the world's largest cyclotron, source of 500 MeV protons, which was named an IEEE Milestone...

       - Located on the campus of the University of British Columbia
      University of British Columbia
      The University of British Columbia is a public research university. UBC’s two main campuses are situated in Vancouver and in Kelowna in the Okanagan Valley...

       (Canada
      Canada
      Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

      )

External links


The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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