The international market for process control and data acquisition software is estimated to be worth $3-5 billion per year. Having been largely eliminated from this market through foreign acquisition during the 1980s, American business now seeks to recapture and expand its market share. The strategy for achieving this goal relies heavily on marketing a control system called EPICS, which was developed through a collaboration between DOE laboratories. The collaborative development of EPICS and its overall utility have also resulted in significant reductions in software development costs for major DOE research projects.
EPICS, the Experimental Physics and Industrial Control System, is a software `toolkit' for building process control systems for a wide variety of applications, both experimental and industrial. The software tools in this kit are independent, expandable modules that can be tailored to serve specific process control functions, making EPICS extremely adaptable. For DOE and academic collaborators, this adaptability plus the collaborative nature of system development means dramatic savings. Such users receive the basic EPICS toolkit free of purchase or licensing costs. New releases are fully tested and documented by members of the EPICS collaboration, and all users share freely in the fruits of system development. This sharing approach provides substantial time and cost savings compared with software development from scratch.
Industry has also recognized the value of EPICS. To date, three companies have signed agreements for the use of EPICS, and two of these, Kinetic Systems and Tate Integrated Systems, are marketing fully developed systems based on the core features of EPICS. Commercial adaptations of EPICS are successfully performing process control functions in numerous commercial installations. Some of these include a storage facility for liquefied natural gas, a distribution system for potable water, and a waste water collection and treatment plant.
In April of 1989, a control group at Argonne National Laboratory (ANL) decided to adapt the GTA control system for use in the Advanced Photon Source (APS), which was in the early stages of development at that time. This decision spoke volumes about the versatility of the existing GTA system, as the GTA was a linear proton accelerator, while the APS was a synchrotron radiation facility whose accelerator and storage ring handled positrons. The members of the APS team also decided to develop their new control system in collaboration with the GTA control group, and a developer from the APS group was detailed to the Los Alamos for an extended period so that he could become thoroughly versed in the system.
Initially, it was expected that this collaboration would produce an adaptation of the GTA system, tailoring it specifically to the requirements of the APS. However, from the project's inception the two groups sought to maximize the system's utility, convenience, and cross-plaform transparency by having both teams carefully examine and approve each proposed system modification. Consequently, as the collaboration proceeded, the two groups began to envisage the possibility of implementing the new version on both projects. This vision enhanced the versatility of the system that emerged, which was renamed EPICS and implemented successfully on both projects.
Following the twin birth of EPICS at these two sites, control groups from other national labs joined the collaboration. Since 1992, developers at Lawrence Berkeley Laboratory have been at work adapting EPICS for use on LBL's new Advanced Light Source, its Gammasphere project, and the STAR detector for Brookhaven National Lab's Relativistic Heavy Ion Collider (RHIC). EPICS application was also under active development at the SSC before that project's cancellation, and CEBAF has recently joined the collaboration.
EPICS users also enjoy the freedom to implement a wide variety of commercial hardware and software modules, freeing them from reliance on particular hardware or software vendors and making it easy to avoid the consequences of hardware obsolescence at the component level. These advantages derive from the fundamental characteristics of EPICS, which are
Its genesis in the field of accelerator control notwithstanding, EPICS is not a ready-made, single-purpose control system, but rather a software `toolkit' for developing systems that serve a wide variety of experimental and industrial applications. These applications can include both control and data acquisition systems that allow extensive operator/experimenter intervention and fully automated control systems more suited to industrial applications. To date, research applications of EPICS have included particle accelerators, free-electron lasers, astronomical telescopes, and physics detectors; the variety of industrial implementations has been noted above. Across this entire spectrum, EPICS has proven its value for providing control functions that include supervisory control, closed-loop control, sequential control, data acquisition, and the optimization of system operation.
EPICS applications can vary as widely in scale as in function. Current EPICS installations include small-scale installations with only a few hundred data channels connecting a single operator workstation to a single I/O-Controller module. (The I/O-Controller modules are hardware units that perform the low-level processing and input/output functions for the EPICS database.) At the other end of the scale are installations with 30 workstations, over 100 CPU-I/O modules, and more than 30,000 data channels. The EPICS installation planned for the SSC would have included more than 100 workstations, 2,000 CPU-I/O modules, and approximately 1,000,000 data channels.
The toolkit approach to system development also makes EPICS relatively easy and inexpensive to adapt for new applications. The system developer has relatively little actual programming to do, as EPICS provides ready-made graphical interface and table entry facilities for this purpose. In addition, the system's modularity means that existing software modules can simply be ignored if they do not need to be implemented, so the developer needn't expend a lot of effort identifing and eliminating unneeded functional modules. For new users, these developmental shortcuts typically yield significant economies in system implementation, with total developmental costs that are as little as 20% of the cost of coding a system from scratch.
In keeping with this emphasis on modularity, EPICS provides a fully distributed system, meaning that any control or data-acquisition/exchange function can be located in any appropriate hardware component. This characteristic is responsible in large measure for the system's speed and robustness, as there are no bottlenecks to slow data travel and no critical links whose failure can disable the entire system.
Additional benefits accrue from the implementation of standards wherever possible. In addition to the Channel Access communications protocol, EPICS adheres strictly to such standards as the C programming language, the UNIX development environment, X-windows graphics, the TCP/IP network protocol, some popular field-bus protocols, and the VME bus. The system's reliance on such standards further simplifies the jobs of system developers, who are free to implement a wide variety of hardware to interface with the system software. Strict adherence to standards also
The aggregate savings in software development costs due to the use of EPICS in all these programs has not been calculated. However, a rough index of the total savings has been provided by the developer of one small detector-control system, who indicated that implementing EPICS had saved that project 20 person-years of software development time.
As noted above, a commercial version of EPICS is also playing a key role in enhancing American competitiveness in the worldwide control system market. As a result of a competitive, equal-opportunity selection process, three American firms have been licensed to use EPICS. These firms are Kinetic Systems Corporation, Tate Integrated Systems, and Titan Spectron Corporation. Of these, both Kinetic and Tate are shipping fully developed systems based on the core features of EPICS. The commercial installations of EPICS to date include: