2 OVERVIEW

The IRACE software consists of three parts - the IRACE front-end controller software, the data acquisition process and the interface libraries.

The front-end controller software runs on the transputer network of the IRACE controller. This software is booted and controlled via an interface process (IRACE command server process - tcomIrcs), which runs on the Ultra-Sparc.

The tasks on the IRACE workstation are started as remote-processes from the instrument workstation. The remote exec- (and remote kill-) functions are part of the interface libraries supplied together with the irace module.

2.2.1 IRACE COMMAND SERVER PROCESS

This process does the protocol conversion to forward commands to the IRACE controller and provides the system services:

- setting of link timeout

Currently the IRACE command server process can handle two link interfaces:

BPP - Sun SBus-Bidirectional Parallel Port (this is the standard parallel port of the SBus based SUN Ultra-Sparc).

ECPP - Sun PCI-Bus via serial port.

2.2.2 SOLARIS DMA ACQUISITION PROCESS

The data acquisition process is a real-time process, that also runs on the Ultra-Sparc. It provides the following parallel tasks:

- Command Interpreter Task (highest priority) for start/stop/parameter-setup and status commands

- Capture-Task (interface to DMA-driver; also does buffer-overrun checks))

- Calculation-Task (parallel computation algorithm)

- Output-Task(s) (transfer data-frames in parallel to any requesting client on any host)

The calculation task is designed as a main-process. The other tasks are started by the main process via functions, which are part of the sdma-library. The sdma-library contains all input-, output-, parameter- and synchronization functions.

This part of the IRACE software is supported for both Sun-Solaris and for HP-UX (simulation mode only, no real-time performance). The EDT DMA interface board is available for both SBus and PCI-Bus based Ultra-Sparcs (pin compatible).

2.2.3 IRACE INTERFACE LIBRARIES

The IRACE interface libraries provide all functions to control both the IRACE controller and the acquisition process. They also contain the functions for data reception. These interface libraries are also supported for both HP-UX and Sun-Solaris.

2.2.4 SIMULATION MODE

In simulation mode a simulator process (tcomScls) is started instead of the IRACE command server process (tcomIrcs). This handles all sequencer, cldc - and status-bus functions and may run either on the IRACE workstation (Ultra-Sparc) or on the instrument workstation.

The acquisition process has a built-in simulator. In simulation mode the input-ringbuffer is pre-filled with data. The input sequence is simulated via timer functions (resolution: 1 ms per input-frame). For simulation on HP-UX the sdma-submodule contains a thread-wrapper (sdmaThr-library) using posix-threads (no real-time performance).

2.3 THE INFRARED DATA ACQUISITION MODULE

The infrared data acquisition module is built on top of the IRACE interface libraries and coordinates the IRACE controller and the acquisition process. This is the interface to the VLT-software. The control server process and the data transfer task are executed on the IWS and the RTD either on the IWS or on the IRACE workstation.

The Science Data is sent to the IWS and stored on the disk as FITS files. The Video Data (RTD data) is sent to the IWS (or to another WS) and displayed in the RTD.

All commands sent by the user must go through the DCS Server on the IWS. Under normal circumstances no commands should be sent directly to other processes.

Not shown in Figure 2 is the RTD Server, which must be running in order to signal to the RTD application to display the data.

Infrared acquisition control processes:


Acquisition Control Server	iracqServer	The WS control server is the interface process to the IRACE-DCS for the external world. Through this server all commands must pass. The server checks the validity of various commands and parameters according to the current state of DCS. The server is running in the IWS environment.
Data Transfer Task	iracqDtt	The Data Transfer Task requests and receives the science data from the IRACE-WS and stores the data in FITS Files. This process is started and stopped by the acquisition control server.

2.4 HOW TO BUILD YOUR OWN APPLICATION

An infrared instrument application consists of a set of configuration files for the IRACE front-end controller (see section 7) and a set of acquisition processes that implement detector read-out specific pre-processing algorithms. Section 4.4 describes in detail how to develop such an acquisition process. Selection and startup of the acquisition process is done by the infrared acquisition control server (iracqServer). The control server also maintains a dynamic parameter interface to the acquisition process.

To introduce instrument specific functions it is also possible to extend the standard server processes and to add application specific control/status widgets to the control panel. This is described in detail in chapter 6.