Introduction

The Secondary Loop Manager (SLM) is an ELT ICS Framework component that manages a configurable number of secondary loops. A secondary loop is a periodic, supervised activity — for example reading a sensor and commanding a device — that runs on a timer while the loop is closed, and that the SLM can open (stop), suspend, resume, and automatically open again when it fails repeatedly.

The SLM is built on the Rapid Application Development (RAD) framework and follows the standard ELT state-machine, OLDB and CII/MAL conventions, so it integrates with the rest of an instrument control system and with the ELT Supervisor.

Scope

This document is the user manual for the ELT ICS Framework - SLM. The intended audience are ELT users, consortia developers and software quality assurance engineers who need to deploy an SLM, customise its loops, or operate it through the GUI and the command-line tool.

Acronyms

CII

Common Infrastructure Interface

CLI

Command-Line Interface

ELT

Extremely Large Telescope

FCF

Function Control Framework

GUI

Graphical User Interface

ICS

Instrument Control System

MAL

Middleware Abstraction Layer

OLDB

Online Database

RAD

Rapid Application Development

SCXML

State Chart XML

SLM

Secondary Loop Manager

Main Components

The SLM is delivered as the following components:

  • A framework library (libifwSlmFramework) implementing the state machine, the per-loop control logic, the OLDB state model and the status publishing. This is the part consortia build upon.

  • A reference server (ifwSlm) that wires the framework together and registers the loop implementations.

  • A Taurus GUI that shows all loops in a table, the time remaining to the next execution, and the connection status, and that sends commands.

  • A command-line tool (slmcli) to send commands to a running SLM.