SOFTWARE INTERFACE

The atif module is responsible for providing the central and only command interface between external users and the TCS. The VLTI Interferometer Supervisor Software is the most typical high level user for the VLTI Auxiliary Telescopes.

The VLTI Supervisor Software user processes communicate with the ATCS by sending commands to and receiving replies from the atif. The atif internally dispatches the commands to the responsible TCS processes, receives their replies and passes them back to the caller.

The atif module uses all functionality of the tif module, but has a specific CDT file and special database clasess.

In order to use atif also tif is required.

The following table alphabetically lists the telescope control commands. On top of these TCS commands, the tif control process accepts all the usual VLT standard commands and a small set of specific commands used for maintenance purposes.

Units and coordinate systems for command parameters follow VLT conventions.

This document describes the interface between AT and ISS, i.e. all the interfaces needed to control the ATs for VLTI observations. TIF in itself will probably also have more commands, used to control the telescope not for pure VLTI coordinating purposes. This anyway does not include operations performed by the operators on control panels. For example operating the enclosure is done via a dedicated AT control panel, that uses internal AT commands, not defined in tif. This is because we do not want enclosure commands to be public for other applications than the operator control panels and AT internal procedures.

tif is a highly flexible piece of software that allows publishing a set of TCS commands and data.
Usually a subset of all available TCS commands is made publicly available. The list can be easily changed and extended or reduced.
ISS will interact with ATCS only through atif. Only data and commands relevant for ISS will be published by ATCS.
Further data and access can be retrieved by the operator via ATCS specific user interfaces, e.g. check of temperatures etc.

The class atifTCS_PUBLIC can be instantiated in any user database to provide a local image of the ATCS public data items. This class is used when the TCS database, real or simulated, is NOT in the same environment as the user database. In this case, the scan system is used to update the user database with values from the ATCS environment (real or simulated).

The class atifTCS_LOCAL has the same structure as atifTCS_PUBLIC (it is a subclass) and provides the same items, but can be instantiated in the same environment where TCS itself is running, i.e. when simulated TCS data are a part of the user database. In this case, the items are updated using the calculation engine, instead of the scan system.

These classes have been implemented to provide access to ATCS data for UIF instrument panels and Sequencer scripts, while C and C++ applications should use the tif Query Library.

For performance reasons, not more than one instance of the classes should be used in each environment.

This has been done in order to allow a more structured access to the items themselves and to optimize performance on the update of the items, that is based on the RTAP calculation engine.

What follows is the structure of the class:

atifTCS_PUBLIC

tcsState - Global TCS state information

tcsState - TCS global state, as in Mode Switching

tcsSubstate - TCS substate, as in Mode Switching

track - TCS tracking flag (0/1)

domeStatus - Current dome Status

times - Time items

lst - Local Sideral Time

utc - Universal Time Coordinated

coord - Target coordinates

ha - Target actual Hour Angle

ra - Target actual RA

dec - Target actual declination

ra2000 - RA at mean place of J2000 in HHMMSS

dec2000 - dec at mean place of J2000 in DDMMSS

ra 2000deg - RA at mean place of J2000 in deg

dec2000deg - dec at mean place of J2000 in deg

alt - Telescope altitude

az - Telescope azimuth

prltic - Actual parallactic angle

track - Tracking parameters

airmass - Actual airmass

dvelra - Differential velocity RA

dveldec - Differential velocity dec

remtime - Remaining tracking time

remlimit - Remaining tracking time limit

trackingLost - Event flag for lost tracking

remTimeLow - Event flag for low remaining trk. time

coude - Coude parameters

state - Guide state

guidingStatus - Guide status

guidingMode - Guide status

trackingState - Tracking state

trackingStatus - Tracking status

RA2000 - RA of current guide star J2000 (HMS)

DEC2000 - dec of current Guide Star J2000 (HMS)

mag - Guide star magnitude

wavelen - Guide star wavelen

probeRA2000 - RA of current guide star J2000 (HMS)

probeDEC2000 - dec of current Guide Star J2000 (HMS)

probeInPos - Guide probe in position

guidingLost - Event: Unexpected loss of guiding

trackingLost - Event: Unexpected loss of tracking

m2 - M2 parameters

focuValue

info - General information

telescop - Telescope name

version - TCS software version in use

installed - TCS software installation date

oper - Telescope Operator name

foculenCO Focus length coude

focuscaleCO Focus scale coude

site - Site information

longi - Longitude

lati - Latitude

level - Height above see level
station - station id string

chop Chopping configuration

status - chopping status (active or not)

startTime - starting time (ISO string)

stopTime - stop time (ISO string)

freq - frequency

throw - amplitude

posOptImage - optimal position for image

peakValleyRatio - peak to valley ratio

telPointingAxis - telescope pointing axes

posAng - chopping angle

offsetChop - chopping offset with respect to center position

asm - Astronomical site monitor

seeing

windspeed

winddir

Note: Add location (station), local seeing (mean, median, max & min), observatory and local coherence time (mean, median, max & min) of the AT.