Integration of PLC with EPICS IOC for SuperKEKB Control System

Recently, more and more PLCs are adopted for various frontend controls of accelerators. It is common to connect the PLCs with higher level frontend computers by the network. As a result, control logic becomes dispersed over separate layers, one of which is implemented by ladder programs for PLCs, and the other is implemented by higher level languages for frontend computers. EPICS-based SuperKEKB (1) accelerator control system, however, take a different approach by using FA- M3 PLCs with its special CPU module, F3RP61, which adopted Linux as its OS and therefore can function as Input/output Controller (IOC. This consolidation of PLC and IOC enables higher level applications to directly reach every PLC placed at frontends by Channel Access (CA). In addition, most of control logic can be implemented by the IOC core program (iocCore) and/or EPICS sequencer to make the system more homogeneous. It results in easier development and maintenance of applications programs. This type of FA-M3-based IOCs are to be used to monitor and control many subsystems of SuperKEKB, such a Low Level RF (LLRF) system, a vacuum control system, a Personnel Protection System (PPS) and so on. This paper describes the FA-M3-based IOC and its applications to the SuperKEKB accelerator control system.