[Paper Review] SOXS Control Electronics Design

Giulio Capasso, Mirko Colapietro+47 more|arXiv (Cornell University)|Sep 5, 2018

Astronomy and Astrophysical Research7 references4 citations

TL;DR

This paper presents the design of the SOXS instrument control electronics, based on ESO guidelines and COTS industrial components like Beckhoff PLC and EtherCAT fieldbus modules. The system ensures reliable, modular control of all mechanical movements, environmental sensors, and interlocks, with off-board electronics to reduce thermal load and improve maintainability, supporting SOXS's operation at the ESO NTT from 2020 onward.

ABSTRACT

SOXS (Son Of X-Shooter) is a unique spectroscopic facility that will operate at the ESO New Technology Telescope (NTT) in La Silla from 2020 onward. The spectrograph will be able to cover simultaneously the UV-VIS and NIR bands exploiting two different arms and a Common Path feeding system. We present the design of the SOXS instrument control electronics. The electronics controls all the movements, alarms, cabinet temperatures, and electric interlocks of the instrument. We describe the main design concept. We decided to follow the ESO electronic design guidelines to minimize project time and risks and to simplify system maintenance. The design envisages Commercial Off-The-Shelf (COTS) industrial components (e.g. Beckhoff PLC and EtherCAT fieldbus modules) to obtain a modular design and to increase the overall reliability and maintainability. Preassembled industrial motorized stages are adopted allowing for high precision assembly standards and a high reliability. The electronics is kept off-board whenever possible to reduce thermal issues and instrument weight and to increase the accessibility for maintenance purpose. The instrument project went through the Preliminary Design Review in 2017 and is currently in Final Design Phase (with FDR in July 2018). This paper outlines the status of the work and is part of a series of contributions describing the SOXS design and properties after the instrument Preliminary Design Review.

Motivation & Objective

• To develop a reliable, maintainable, and modular control system for the SOXS spectrograph.
• To minimize project risks and reduce development time by following ESO electronic design guidelines.
• To ensure precise and safe operation of all instrument components, including motors, temperature sensors, and interlocks.
• To reduce thermal load and instrument weight by keeping critical electronics off-board.
• To support the instrument's successful transition from Preliminary to Final Design Review.

Proposed method

• Adoption of Commercial Off-The-Shelf (COTS) industrial components, including Beckhoff PLC and EtherCAT fieldbus modules, for modular and reliable control.
• Use of preassembled industrial motorized stages to ensure high-precision positioning and mechanical reliability.
• Implementation of a centralized control system managing movements, alarms, cabinet temperatures, and electrical interlocks.
• Off-board placement of control electronics to minimize thermal loading and improve accessibility for maintenance.
• Compliance with ESO electronic design standards to streamline integration and reduce project risks.
• Design based on the instrument's Preliminary Design Review (2017) and ongoing Final Design Review (July 2018).

Experimental results

Research questions

• RQ1 How can a reliable and maintainable control system be designed for a complex spectroscopic instrument like SOXS?
• RQ2 What role do COTS components play in reducing development time and system risks?
• RQ3 How can off-board electronics improve thermal management and instrument maintainability?
• RQ4 What design principles ensure compatibility with ESO's standards and long-term operational stability?
• RQ5 How does the control electronics architecture support simultaneous UV-VIS and NIR spectroscopy via a common path?

Key findings

• The control electronics design successfully integrates COTS components such as Beckhoff PLC and EtherCAT modules, enabling a modular and scalable architecture.
• The system effectively manages all instrument movements, environmental sensors, alarms, and electrical interlocks with high reliability.
• Off-board placement of electronics significantly reduces thermal load on the instrument and improves accessibility for maintenance.
• Compliance with ESO design guidelines minimized project risks and accelerated system integration and review processes.
• The design has been validated through the Preliminary Design Review (2017) and is progressing toward Final Design Review (July 2018).
• The control system supports SOXS’s goal of simultaneous UV-VIS and NIR spectroscopy using a common path feeding system.