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NCS Architecture

Distributed Control

The NCS is a distributed system of processes that

The processes are running on a set of processors connected to the local ethernet. (list of processes, list of processors)

Communication between the processes is done by several means:

Control Systems

We defined a set of "control system" processes that cooperate in the processing of an observation. The control processes

We have the following control systems:

Synchronization of Control Systems

The tasks of the NCS control systems have to be synchronized between the different control systems. Examples:

As the NCS was designed to be a distributed system, we defined so-called "synchronization messages" that can be used by a process to indicate an event that other processes might want to wait for. A process can wait for a specific synchronization message. The format of a message is <sender>:<identifier>:<event>, e.g., antCS:2007-02-11.113.12:subscanDone .

In the NCS, we took the approach that the end of a subscan is defined by one of the control systems. For now, this is mostly the antennaControlSystem (antCS), except for the case of calibrations, where the control is with the receiverControlSystem (rxCS). For each subscan, therefore one of the control systems takes the role of the "masterControlSystrem" (masterCS) and other control systems can just wait for events from the masterCS without having to know which control system is currently the masterCS.

As a synchronization message can be sent before a specific process wait for it, a process "syncLogger" captures all synchronization messages and keep them in a database. Process can consult the database messages that have arrived.

Coordinator

The coordinator.py program coordinates the execution of observations. It reads submitted [NcsObservationSpecification observation specifications] from the [NcsObservationQueues current observation queue]. The coordinator executes the observation in cooperation with several processes called controlSystems, plus a large number of processes running on hosts of the local network.

Steps:

Short Overview (for presentation HU 2015-10)

Control Hardware

The 30m telescope control (NCS) is based on:

Software Concepts


CategoryNcs

NcsArchitecture (last edited 2015-09-22 07:49:03 by WalterBrunswig)