The MICADO first light imager for the ELT: PLC-based software design for cryogenic control

The Multi-Adaptive Optics Imaging Camera for Deep Observations (MICADO) is one of the first light ESO Extremely-Large-Telescope (ELT) Instruments and is now nearing the completion of its final design stage. The MICADO instrument aims to generate high-resolution images of the Universe at near-infrared wavelengths, which requires maintaining a stable vacuum environment at 82 K inside the MICADO cryostat. To fulfill this requirement and for safety reasons, a PLC-based control software is used. This software communicates with over 180 sensors and devices simultaneously, to remotely maintain the cryostat environment. This paper discusses the software’s design architecture and implementation.