Mount Control System of the ASTRI SST-2M prototype for the Cherenkov Telescope Array

The ASTRI SST-2M telescope is an end-to-end prototype proposed for the Small Size class of Telescopes (SST) of the future Cherenkov Telescope Array (CTA). The prototype is installed in Italy at the INAF observing station located at Serra La Nave on Mount Etna (Sicily) and it was inaugurated on September 2014. This paper presents the software and hardware architecture and development of the system dedicated to the control of the mount, health, safety and monitoring systems of the ASTRI SST-2M telescope prototype. The Mount control system installed on the ASTRI SST-2M telescope prototype makes use of standard and widely-deployed industrial hardware and software. State of the art of the control and automation industries was selected in order to fulfill the Mount-related functional and safety requirements with assembly compactness, high reliability and reduced maintenance. The software package was implemented with the Beckhoff TwinCAT version 3 environment for the software Programmable Logical Controller (PLC), while the control electronics have been chosen in order to maximize the homogeneity and the real-time performance of the system. The integration with the high-level controller (Telescope Control System) has been carried out by choosing the Open Platform Communications Unified Architecture (UA) protocol, supporting rich data model while offering compatibility with the PLC platform. In this contribution we show how the ASTRI approach for the design and implementation of the Mount control system has made the ASTRI SST-2M prototype a stand-alone intelligent machine, able to fulfill requirements and easy to be integrated in an array configuration such as the future ASTRI mini-array proposed to be installed at the southern site of the Cherenkov Telescope Array (CTA).