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The new HERMES spectrograph represents the first foray by AAO into the use of commercial off-the-shelf industrial field bus technology for instrument control, and we regard the final system, with its relatively simple wiring requirements, as a great success. However, both software and hardware teams had to work together to solve a number of problems integrating the chosen CANopen/CAN bus system into our normal observing systems. A Linux system running in an industrial PC chassis ran the HERMES control software, using a PCI CAN bus interface connected to a number of distributed CANopen/CAN bus I/O devices and servo amplifiers. In the main, the servo amplifiers performed impressively, although some experimentation with homing algorithms was required, and we hit a significant hurdle when we discovered that we needed to disable some of the encoders used during observations; we learned a lot about how servo amplifiers respond when their encoders are turned off, and about how encoders react to losing power. The software was based around a commercial CANopen library from Copley Controls. Early worries about how this heavily multithreaded library would work with our standard data acquisition system led to the development of a very low-level CANopen software simulator to verify the design. This also enabled the software group to develop and test almost all the control software well in advance of the construction of the hardware. In the end, the instrument went from initial installation at the telescope to successful commissioning remarkably smoothly.

MUSE (Multi Unit Spectroscopic Explorer) is a second generation VLT panoramic integral field spectrograph developed for the European Southern Observatory (ESO), operating in the visible wavelength range (0.465-0.93 μm). The MUSE instrument is currently under integration and the commissioning is expected to start at the beginning of year 2013. The scientific and technical capabilities of MUSE are described in a series of 19 companion papers. The Fore-Optics (FO), situated at the entrance of MUSE, is used to de-rotate and provide an anamorphic magnification (x 5 / x 2.5) of the 1 arc minute square field of view from the F/15.2 VLT Nasmyth focal plane (Wide Field Mode, WFM). Additional optical elements can be inserted in the optical beam to further increase the magnification by a factor 8 (Narrow Field Mode, NFM). An atmospheric dispersion corrector is also added in the NFM. Two image stabilization units have been developed to ensure a stabilization of the field of view (1/20 of a resolved element) for each observation mode. Environmental values such as temperature and hygrometry are monitored to inform about the observation conditions. All motorized functions and sensors are remote-controlled from the VLT Software via the CAN bus with CANOpen protocol. In this paper, we describe the FO optical, mechanical and control/command electronic concept, development and performance.

The Hobby-Eberly Telescope (HET) will be undergoing a major upgrade as a precursor to the HET Dark Energy Experiment (HETDEX ‡ ). As part of this upgrade, the Prime Focus Instrument Package (PFIP) will be replaced with a new design that supports the HETDEX requirements along with the existing suite of instruments and anticipated future additions. This paper describes the new PFIP control system hardware plus the physical constraints and other considerations driving its design. Because of its location at the top end of the telescope, the new PFIP is essentially a stand-alone remote automation island containing over a dozen subsystems. Within the PFIP, motion controllers and modular IO systems are interconnected using a local Controller Area Network (CAN) bus and the CANOpen messaging protocol. CCD cameras that are equipped only with USB 2.0 interfaces are connected to a local Ethernet network via small microcontroller boards running embedded Linux. Links to ground-level systems pass through a 100 m cable bundle and use Ethernet over fiber optic cable exclusively; communications are either direct or through Ethernet/CAN gateways that pass CANOpen messages transparently. All of the control system hardware components are commercially available, designed for rugged industrial applications, and rated for extended temperature operation down to -10 °C.

This paper describes both the electronics design (ED) and the acceptance control system (ACS) of the Commissioning Instrument (CI) for the Gran Telescopio Canarias (GTC). The CI mainly comprises ten mechanisms accurately positioned by control algorithms, which in turn are programmed according to the CI operation modes. The control system is based on a CANopen protocol and is completely compatible with the GTC control system. CANopen is a serial communication protocol based on CAN bus. The CANopen features allow for the control system high reliability. A Reliability, Availability, Maintainability, and Safety (RAMS) analysis was carried out to guarantee the CI opto-mechanics and electronics performance.