2.2.2. General Requirements#

General Requirements involve: SWCS common standards, environmental and health, general services, maintenance, documentation, and testing – items which are required to establish and maintain the baseline health and proper functioning the observatory at all times that GMTO is in operation. The items are briefly summarized below.

Standards Requiremnets

Standards Requirements involve SWCS standards that enable the integration of software and hardware into a coherent telescope system, whereas data formats standards establish common practices for properly expressing and representing numerical and science data.

  • SWCS standards -– The SWCS standards require that the SWCS establish a reference model for a control subsystem, software and hardware standards (SWC-REF-00029) and comply with electronic, software (operating systems, user interface libraries, distributed system libraries, network, databases, etc.), and hardware standards (control computers, PLCs, workstations, servers, I/O modules, fieldbuses and network).

  • Data Formats -– Data format standards require that the SWCS use SI units, that all numerical values which represent physical magnitudes have units, that GMT adopt the Flexible Image Transport Systems (FITS) to record science observations, that the GMT data be compliant with Virtual Observatory standards, and that the SWCS provide a data archive system for collecting, storing, and retrieving all raw data and metadata acquired during observations for the lifetime of the observatory.

Health and Safety Requirements

To establish a safe working environment, the GMT project adopts industry standards presented in the document: GMT Compliance to Regulations, Codes and Standards [Sawy12a], which the SWCS inheritsa nd complies with as the baseline. The Hazard Analysis process described in Chapter 5.11 of the SLPDR identifies safety risks and defines mitigation actions that are allocated to GMT subsystems, including the SWCS. The SWCS is required to provide capabilities: to continuously monitor performance, status, and health of the system; to interface with the Interlock and Safety System; to enhance the safety and integrity of the system with software; to include redundant safety limits on moving parts that have risk implications for the hardware or personnel; and to enable manual interlock override without interference from software. However the SWCS is not ultimately responsible for the safety of the personnel and the system. The SWCS must also inherit operating limits established by Level 2 requirements, such as observing limits for science observations that include absolute hardware and software limit-switches. In case of central control failure (e.g., in the observatory control system, operator console), all critical subsystems will have built-in time-outs. Lastly, the SWCS will provide status information for: common operating states, alarm conditions, trip conditions and corrective actions, power supply, and other items required to operate subsystems from the control room.

Environmental Requirements

Environmental requirements facilitate the optimal use of the observatory by monitoring the atmosphere and weather forecasts to aid observation scheduling, planning, and on-the-fly decision making. The requirements protect the observatory and instruments actively during adverse weather (lightning, rain, and wind storms) and earthquakes by triggering emergency procedures automatically or with operator supervision. The electronic and hardware components must also be protected passively from moisture, power surges, wind, etc.

The Environmental Requirements stipulate that the GMT will be operated centrally from a control room, and that electronic equipment for operating the telescope, AO, and instruments will be located in the electronics room. The SWCS will provide capabilities: to access weather forecasting; to interface to the environment monitoring facility to monitor dust, atmospheric turbulence, water vapor, atmospheric seeing, weather conditions; and to record, and make accessible, all environmental statistics. In the event of an earthquake, the SWCS is designed to survive without structure failure up to a maximum level defined in the document on GMT Environmental Conditions [Mait12]. The SWCS will provide capability to execute automated safety procedures to protect personnel, the telescope, enclosure, instruments, and electrical systems, in the event of loss of power, storms, lightning, and earthquakes.

Services Requirements

Service requirements involve power, electrical grounding, liquid cooling, compressed air, nitrogen, helium, communication lines, electronic cabinets, and washing services. GMTO will utilize Chilean standard voltages (380V 3-phase and 220V single phase) and frequency (50 Hz), backed up by on-site emergency power generators, and supplied to the telescope through various power distribution panels and electronics cabinets installed as part of the telescope systems utilities infrastructure. The SWCS hardware (e.g., computers, networking equipment) will run off of UPS as per the GMT Common Utilities power budget (GMT-SE-REF-00366).

  • Power -– The requirements for the electrical power systems are defined in GMT Electrical Power Systems [Sawy12b] and Telescope Common Utilities and Equipment [Sawy12c]. The SWCS is required to provide cabling infrastructure to support safe installation and operation of the GMT control system.

  • Grounds -– In addition to the grounds associated with power feeds to various sub-circuits and equipment on the telescope, additional circuits will be required to electrically ground the structures of the moving components (azimuth disk, Optical Support Structure, and GIR), and other locations to isolate noise sensitive equipment. The SWCS equipment will be compatible with the GMT power filtering and grounding system, which has been designed to minimize electrical interference.

  • Electronics Cabinets -– According to the document Telescope Common Utilities and Equipment8, there are 8 service bays on the GIR that will be used for placing 16 electronics cabinets. The IP platform and azimuth platform structures will also include an area for locating electronic cabinets. The Standard Electronics Cabinets (SEC) includes active heat removal for a maximum of 2000 W, and feature remote power on/off control. Each SEC provides 2200W of 220V UPS. The SEC maintains the air inside the cabinet to an average temperature of ambient ± 2C. The SWCS hardware components will be designed to allow adequate installation clearances inside the SEC and will provide the local control of the cabinets and the integration with the supervisory components of the Observatory Control System for global start-stop sequences and health monitoring.

Reliability and Maintainability Requirements

These requirements promote system reliability and facilitate routine maintenance. Reliability is achieved by: using high quality components, over-specifying or overrating equipment, implementing contamination control, using proven design techniques, designing for ease of serviceability, and providing adequate spare parts. The SWCS will provide: an engineering mode to allow low-level control of components and subsystems; software tools to display real-time and long-term performance trends of components and subsystems; an ability to correlate time-stamped data with other subsystems. The SWCS will also provide equipment, procedures, and safe access, to maintain and service all critical components. The SWCS will provide the capability to achieve maintenance time requirements per Maintenance Time Budget (GMT-SE-DOC-00420). The SWCS will also standardize common components to optimize the stock and number of different spare parts.

Documentation Requirements

The SWCS will provide documentation needed to operate, support, and maintain the GMT. All SWCS documentation will be accessible, searchable, and retrievable on-line. SWCS documentation will also provide access to user guides for all equipment and facility instrumentation used during routine operations, technical documentation (manuals, drawings), and electronics schematics.

Testing Requirements

Testing requirements pertain to testing and verification of the GMT software, instruments, and subsystems produced by all the partners and subcontractors working with and for the project. The SWCS will develop software modules that have automated test procedures, and that support testing for backward compatibility. Contractors and procurement suppliers must provide SWCS all necessary software and hardware tools for factory acceptance testing. Documentation for testing includes information on the version of equipment, version of test specification, and version of design specification, for every test (unit testing, system and integration, acceptance). The SWCS will generate a report that tracks all requirements that are fulfilled, unfulfilled, or unverifiable, using a common template. All the software components of the SWCS will be subject to a Continuous Integration Process with the goal of ensuring interface compatibility before the final integration. The Continuous Integration Process will also include automated unit and integration testing as the software modules are incrementally developed. This process will include all the software components, regardless of the organization procuring them.