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Proceedings Paper

MICADO instrument control approach in context of ESO ELT standards
Author(s): Marco Haeuser; Joerg Schlichter; Hans-Joachim Hess; Helmut Kravcar; Josef Richter; Michael Wegner
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Paper Abstract

MICADO will equip the ELT with a first light capability for diffraction limited imaging at near-infrared wave- lengths. The instrument’s observing modes focus on various flavours of imaging, including astrometric, high contrast, and time resolved. There is also a single object spectroscopic mode optimised for wavelength coverage at moderately high resolution.1 Due to ESO’s technology standards evolution from VLT to ELT, MICADO will manifest the combined, PLC based soft- and hardware control. The evolution of ESO’s technology design guidelines is on the one hand triggered by the ongoing developments in modern days industry and consumer tech- nology. On the other hand, ELT’s sheer dimensions request increasingly complex and smart solutions onwards controlling and monitoring such huge instruments. ESO’s control concept is based on a two layer approach: PLCs are responsible for low-level hardware control (in a real-time fashion, if necessary), while software running on a Linux workstation implements the astronomic business logic of the control system. Development is eased by the fact that ESO delivers libraries for the control of many standard hardware components. A very interesting feature of this approach is the possibility to run C++ code natively inside a PLC real-time environment. This will be used for the control of complex mechanisms like the MICADO Atmoshperic Dispersion Corrector (ADC). This contribution provides an overview of the key functionality of the instrument focusing on the mechanisms inside the cryostat, and an overview of the cryogenic control. Because of hardware and cryogenic safety reasons, the cryostat control PLC system will be designed as a closed PLC based control system. Hence commands will only be accepted from a human machine interface located next to the cryostat itself. All cryostat parameters and according sensor readings will be published via OpcUA, allowing for full remote cryostat monitoring. In contrast, the instrument control PLC system will interact with the higher level software using the advantages of the industrial OpcUA communication standard and will therefore allow for remote control. Further configuration and commissioning of those mechanisms is made conveniently accessible via this approach. All this is based on ESO’s concept for Line replaceable Units (LRU), which utilizes Beckhoff PLC units to ensure maintainability, availability.

Paper Details

Date Published: 27 July 2018
PDF: 12 pages
Proc. SPIE 10702, Ground-based and Airborne Instrumentation for Astronomy VII, 107028Z (27 July 2018); doi: 10.1117/12.2312048
Show Author Affiliations
Marco Haeuser, Univ.-Sternwarte München (Germany)
Joerg Schlichter, Univ.-Sternwarte München (Germany)
Hans-Joachim Hess, Univ.-Sternwarte München (Germany)
Helmut Kravcar, Univ.-Sternwarte München (Germany)
Josef Richter, Univ.-Sternwarte München (Germany)
Michael Wegner, Univ.-Sternwarte München (Germany)

Published in SPIE Proceedings Vol. 10702:
Ground-based and Airborne Instrumentation for Astronomy VII
Christopher J. Evans; Luc Simard; Hideki Takami, Editor(s)

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