The Experimental Physics and Industrial Control System (EPICS), has been used at a number of sites for performing data acquisition, supervisory control, closed-loop control, sequ,ential control, and operational optimization. The EPICS architecture was originally developed by a group with diverse backgrounds in physics and industrial control. The current architecture represents one instance of the 'standard model'. It provides distributed processing and communication from any LAN device to the front end controllers. This paper will present the genealogy, current architecture, performance envelope, current installations, and planned extensions for requirements not met by the current architecture.

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Currently more than 70 organizations have obtained permission to use EPICS, a set of software packages for building real-time control systems. In this paper representatives from four of these sites discuss the reasons their sites chose EPICS, provide a brief discussion of their control system development, and discuss additional control system tools obtained elsewhere or developed locally.

This document describes the core software that resides in an Input/Output Controller (IOC), one of the major components of EPICS. It is intended for anyone developing EPICS IOC databases and/or new record/device/driver support. The plan of the book is: EPICS Overview An overview of EPICS is presented, showing how the IOC software fits into EPICS. This is the only chapter that discusses OPI software and Channel Access rather than just IOC related topics. Database Locking, Scanning, and Processing Overview of three closely related IOC concepts. These concepts are at the heart of what constitutes an EPICS IOC. Chapter 1: EPICS Overview Getting Started 12 EPICS IOC Application Developer's Guide Another way to create the breakpoint table is to include the following definition in a Makefile.Vx: BPTS += bptXXX.dbd NOTE: This requires the naming convention that all data tables are of the form bpt.data and a breakpoint table bpt.dbd. Menu and Record Type Include File Generation. Access Security Application Programmer's Interface EPICS Release: R3.13.0beta12 EPICS IOC Application Developer's Guide 63 change Client long asChangeClient(ASCLIENTPVT ppvt,int asl, char *user,char*host); This routine changes one or more of the values asl, user, and host for an existing client. Again the caller must provide permanent storage for user and host. It is permissible to use the same user and host used in the call to asAddClient with different values. This routine returns S_asLib_asNotActive without doing anything if access control is not active. remove Client long asRemoveClient(ASCLIENTPVT *pvt); This call removes a client. This routine returns S_asLib_asNotActive without doing anything if access control is not active. get Client Pvt void *asGetClientPvt(ASCLIENTPVT pvt); For each client, the access system keeps a pointer that can be used by the caller. This routine returns the value of the pointer. This routine returns NULL if access security is not active. put Client Pvt void asPutClientPvt(ASCLIENTPVT pvt, void *userPvt); This routine is used to set the pointer returned by asGetClientPvt. register Callback long asRegisterClientCallback(ASCLIENTPVT pvt, ASCLIENTCALLBACK pcallback); This routine registers a callback that will be called whenever the access privilege of the client changes. This routine returns S_asLib_asNotActive without doing anything if access control is not active. check Get long asCheckGet(ASCLIENTPVT pvt); This routine, actually a macro, returns (TRUE,FALSE) if the client (has, doesn't have) get access rights. check Put long asCheckPut(ASCLIENTPVT pvt); This routine, actually a macro, returns (TRUE,FALSE) if the client (has, doesn't have) put access rights Access Computation compute all Asg long asComputeAllAsg(void); This routine calls asComputeAsg for each access security group.