EPICS Gets System Problems under Control

Sophisticated control systems for large, complex operations, such as major scientific facilities, manufacturing plants, and storage/distribution facilities, are not readily transplanted from one site to another. Instead, system designers expend vast amounts of time and money to "reinvent the wheel" for their particular facility. Now, a multi-laboratory collaborative effort, in which Argonne National Laboratory is an important player, has produced a system that lets application developers create control systems for any type of facility. First developed for particle accelerators, the Experimental Physics and Industrial Control System (EPICS) gives designers a "universal" solution to computerized control.

EPICS is extremely flexible and open-ended. Different implementations of the system — say, one used to control particle accelerator operations at a research facility and another used to handle a large-scale manufacturing or refining plant's needs — might use entirely different sets of tools, designed to serve highly diverse applications. Yet the same design philosophy, methods, and overall system architecture would apply to both.

A major factor in the success of EPICS is the tool-based approach taken by its designers, minimizing the need for custom coding . The software "tools" incorporated in the system are designed to permit independent development, as well as to use appropriate protocols and maintain well-chosen boundaries between modules. New software tools can be developed to replace existing ones or to serve new purposes; EPICS is so designed that the presence or absence of any particular tool should have no impact on other tools or functions.

Among the many tools, for instance, is "Alarm Handler," one of Argonne's first contributions to the EPICS collaboration. Dealing with alarms is a challenge in any control system; the larger and more complex the system, the bigger the problems become, including "alarm storms" that waste time and resources. In developing Alarm Handler, Argonne had the opportunity to fine-tune it under "real world" conditions at the Thomas Jefferson National Accelerator Facility. The tool has been incorporated into control systems for Argonne's Advanced Photon Source and other accelerator-based facilities.

EPICS is the product of a continuing co-development effort. Initially, Los Alamos National Laboratory developed an operator interface for what would eventually become EPICS as part of a control system built for Argonne's Intense Pulsed Neutron Source. Next, faced with building a control system for a major new accelerator, the Advanced Photon Source (APS), Argonne's design team suggested a collaboration with the Los Alamos team. This effort was so successful that other research organizations, in the United States and abroad, have joined in to continue improving EPICS.

Today, EPICS is being used at more than 100 sites worldwide. EPICS-based systems are in service at a number of particle accelerators, detectors, and astronomical instruments, while water distribution networks, oil field extraction systems, and plants for wastewater treatment and gas liquefaction are among the successful commercial applications.

Development of EPICS was funded by the U.S. Department of Energy, Office of Science, Basic Energy Research.

Technical Information

Based on a Unix development and operator interface environment, EPICS is written in the C and C++ programming languages. The EPICS operator interface uses Unix-based workstations (currently SUN and HP are supported), running the Unix operating system, X Windows, and the Motif Toolkit. PCs using Motif libraries are also supported. The local area network (LAN) is based on any media that use TCP/IP communication protocols (via sockets). Input/output controller (IOC) hardware includes the VME-VXI bus/crate system and various modules, as well as various processors, with the Motorola 680xx and Power PC being the most prevelent. IOCs based on PCs are also supported. Various subnetworks, such as Allen Bradley , GPIB, CAN, Modbus and BitBus, are supported. Software for IOC applications is vXWorks from Wind River Systems, a real-time system with extensive Unix-like libraries.

EPICS is a completely distributed system (thereby avoiding bottlenecks); it scales well, and its input/output controllers are autonomous systems. It is "event-driven" (providing quick response) and is designed for high performance (display call-up is rapid, and input/output controllers can process more than 5,000 records per second).

Los Alamos, Argonne, and the Department of Energy have signed a nonexclusive license agreement with three commercial firms for the use of an earlier version of EPICS. These firms — KineticSystems Corp. (Denver, Colo.), Tate Integrated Systems (Baltimore, Md.), and Titan Corp. (Albuquerque, N.M.) — are separately developing and marketing new software products spun off from EPICS. Other organizations — Lawrence Berkeley Laboratory, the Spallation Neutron Source Collaboration, the Thomas Jefferson National Accelerator Facility (home of the Continuous Electron Beam Accelerator Facility, CEBAF), and two German accelerator facilities, BESSY and DESY — have joined the EPICS collaboration.

Development funded by U.S. Department of Energy, Office of Science (formerly Office of Energy Research), Basic Energy Research.