The EPICS toolkit consists of a set of software components with which Application Developers can create a control system. The basic component types are:
•OPI
Operator Interface. A UNIX- or NT-based workstation or PC which can run various EPICS tools—the “clients.”
•IOC
Input Output Controller. A VME/VXI-based chassis containing a Motorola 68K or PPC processor with various VME I/O modules for analog and digital signals, and for access to field buses such as Allen-Bradley, GPIB, CANbus or CAMAC.
•LAN
TCP/IP-based Local Area Network. A communication network which connects the IOCs and OPIs. EPICS provides a software com- ponent, Channel Access, which provides network transparent commu- nication between every client—such as OPI—and an arbitrary number of servers—such as IOC.

EPICS Attributes
•Tool Based
EPICS provides a number of tools both for creating and also for
operating a control system. This minimizes the need for custom
coding and helps ensure uniform operator interfaces.
•Distributed
An arbitrary number of IOCs and OPIs can be supported. If a single IOC becomes saturated, its functions may be spread over several IOCs.
•Event Driven Network loading and message latency are simultaneously minimized by allowing only changes to a datum to be sent by servers to clients (“reporting by exception”).
•Customization Users may add new components to support their applications; they are configured using simple ascii tables.
•Scalable
Systems from a few to 100,000 “channels” supported.
•Modular
Distinct “software buses” at several layers allow good decoupling between clients and servers, across versions, and mixed hardware.
•Platforms
Runs on most Unix workstations, VMS, Windows NT.

Download pdf Experimental Physics and Industrial Control System (EPICS) Tutorial