Integration of S7 programmable logic controller in EPICS

In the control system of linear induction accelerator (LIA), Programmable Logic Controller (PLC) is widely used as front end controller in personal protection system (PPS). It is necessary to integrate PLC into input/output controller (IOC) based on EPICS. This paper introduces a new communication method between IOC and PLC based on S7nodave device support and asynchronous communication module, which can achieve the transparent access of IOC to S7 PLC process image area and memory variables without establishing communication buffer, thus keep the independence of the PLC programs. This paper also presents the development procedures and operating interface for PPS.