ECMC, the Open Source Motion Control Package for EtherCAT Hardware at the ESS
Thomas Gahl, Brodrick, David, Torsten Bögershausen, O. Kirstein, Timo Korhonen, Daniel Piso, Anders Sandström · JACOW · 2018
In industry the open standard EtherCAT* is well established as a real-time fieldbus for largely distributed and synchronised systems. Open source solutions for the bus master have been first introduced in scientific installations by Diamond Light Source** and PSI using EtherCAT hardware for digital and analog I/Os. The European Spallation Source (ESS) decided to establish open source EtherCAT systems for mid-performance data acquisition and motion control on accelerator applications. In this contribution we present the motion control software package ECMC developed at the ESS using the open source Etherlab*** master to control the EtherCAT bus. The motion control interfaces with a model 3 driver to the EPICS motor record supporting it's functionalities like positioning, jogging, homing and soft/hard limits. Advanced functionalities supported by ECMC are full servo-loop feedback, a scripting language for custom synchronisation of different axes, virtual axes, externally triggered position capture and interlocking. On the example of prototyping a 2-axis wire scanner we show a fully EPICS integrated application of ECMC on different EtherCAT and CPU hardware platforms.