LINAC2026 - 33rd Linear Accelerator Conference

Implementation of an EPICS and EtherCAT-based PLC replacement system in PAL-XFEL

TUPO085

18 Aug 2026, 16:00

2h

1F Exhibition Hall (Daejeon Convention Center)

Poster Presentation MC4.A05: Other technology TUPO - Poster Session

Speaker

Geonyeong Mun (Pohang Accelerator Laboratory)

Description

PAL-XFEL is a fourth-generation X-ray free electron laser facility in Pohang, Korea. The existing operation mode PLC system interfaced with the Personnel Safety Interlock System (PSI) using a legacy embedded PLC platform that had reached end-of-life status. To replace the system while maintaining compatibility with the existing infrastructure, a new control system based on Raspberry Pi 5, EtherCAT I/O modules, and EPICS IOC was developed.

The EtherCAT master was implemented using EtherLab integrated directly into the EPICS IOC application. Existing dry-contact interfaces and EPICS PV naming structures were preserved using PV alias configuration, allowing the existing PSI ladder logic and operator interface to remain unchanged.

PREEMPT_RT Linux and CPU isolation techniques were applied to improve deterministic real-time performance. The developed system was successfully installed and verified through PSI interlock tests during PAL-XFEL maintenance operation.