SKA South Africa, National Research Foundation of South Africa, Cape Town, South Africa
The 64-dish MeerKAT radio telescope, currently under construction, comprises several loosely coupled independent subsystems, requiring a higher level Control and Monitoring (CAM) system to operate as a coherent instrument. Many control-system architectures are bus-like, clients directly \mbox{receiving} monitoring points from Input/Output Controllers; instead a multi-layer architecture based on point-to-point Karoo Array Telescope Control Protocol (KATCP) connections is used for MeerKAT. Clients (e.g. operators or scientists) only communicate directly with the outer layer of the telescope; only telescope interactions required for the given role are exposed to the user. The layers, interconnections, and how this architecture is used to meet telescope system requirements are described. Requirements include: Independently controllable telescope subsets; dynamically allocating telescope resources to individual users or observations, preventing the control of resources not allocated to them; commensal observations sharing resources; automatic detection of, and responses to, system-level alarm events; high level operator controls and health displays; automatic execution of scheduled observations.
