Implementation of EPU66S control system at the Taiwan Photon Source

The EPU66S, an elliptically polarized undulator with a 66 mm period, is a component of the Phase III beamline project at the Taiwan Photon Source (TPS). It was successfully installed in the TPS storage ring in January 2025. The control system for the EPU66S is developed within the EPICS framework, integrating motion controllers and EtherCAT communication. This system also includes a safety interlock mechanism, which halts motion in response to limit switches, torque limit switches, emergency stop button, and linear optical encoder feedback. To ensure smooth operational testing, all hardware and software components of the EPU66S control system were fully integrated prior to installation. This paper presents the development process of the EPU66S control system, with a focus on the optimization of its motion control test platform.