EPICS

EPICS ( Experimental Physics and Industrial Control for System) is a software environment to develop distributed control systems for large-scale experiments such as particle accelerators and telescopes and to realize. EPICS provides this SCADA support.

EPICS uses a client-server and publish-subscribe techniques of communication between the various computers used. A variety of computer, Input / Output Controller (IOC ), collected in real time via the connected measuring instruments experiment and control data. A special network protocol called Channel Access ( CA) this information to another computer places the clients passed. CA supports soft real -time requirements, such as occur in scientific experiments.

Input / Output Controller

The IOCs are either commercially available personal computers or standard VME processors meeting certain modules ( such as GPIB or RS232) Manage, in turn, with control system instruments ( oscilloscopes, network analyzers ) and devices (motors, thermocouples, switches and so etc.) are connected.

The IOC runs a database of records that represent either devices or properties of the devices to be controlled. IOC software for hard real-time conditions normally used RTEMS or VxWorks, although it is working on porting to other systems. IOC software for soft real-time constraints sometimes runs on Linux or Windows systems.

Other computers in the network can communicate with the IOC about the concept of channels. Serve as an example a particle accelerator with valves between sections. For a valve, there would typically several channels: a output channel to remotely open the valve or close; an input channel to query the state of the valve (eg, closed, open, in progress); and perhaps more analog input channels, the temperature and pressure on each side of the valve representative.

Often a GUI package such as EDM ( Editor / Display Manager) or MEDM (Motif EDM) is used on the clients. These allow the generation and use of scales, pointers, text boxes, simple animations, etc.