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Problem

Is it possible to run telescope software without the telescope?

Solution

If you are a member of the SDD, then mostly yes; the devices listed in /home/sim/etc/config/devices.conf plus all user programs are available for simulation.

The SDD telescope simulator is more properly called a software testbed, as it runs the development version of the system software (which, by its definition, is continually in flux). Its purpose is to allow the SDD to test out the software changes making their way into the next release of the M&C system. Consequently, it is not suitable for general use by observers and other staff not intimately involved in software develoment, or ready to accept the instabilites that are characteristic of software under development.

An actual telescope simulator running an exact copy of the currently released software is a very desirable thing for users, but it will have to wait until time is available to set it up, currently scheduled for Cycle 8 of this year. Until that time we (the Change Control Committee) all agree that use of this testbed (formerly known as the simulator) should be restricted to SDD and Richard. No support will be provided if any astronomers choose to use it.

Where the simulator lives

The simulator runs on hosts leeloo, muacu, and landru. Its files are laid out exactly as the real telescope, i.e.:

The telescope and simulator share the same source directories (except for configuration files).

How to run the simulator

To set up your environment to run the simulator: source /home/sim/gbt.bash and then /home/sim/sparrow/sparrow.bash (source the sparrow.bash after changing the link to your sparrow code, as directed below).

How to prepare code to run on the simulator.

No preparation is needed, exactly the same code is installed and run on the telescope and simulator, the only differences are the contents of the files in YGOR_TELESCOPE/etc/config. For Ygor, one needs to install into a directory in /home/simversions. For Sparrow, one needs to configure the simulator to use the desired version (see below).

What it cannot do

Besides the devices commented out in /home/sim/etc/config/devices.conf, the simulator does not attempt to produce even nominally realistic data files. This prevents the simulator from being very useful for programs whose input is data such as analysis packages. Most of the monitors produce realistic -- though static -- values. More obviously, the simulator does not exercise the hardware drivers in the control software.

How to configure the simulator

One has the option of selecting versions for Ygor and Sparrow independently.

To select among the versions of Ygor installed in /home/simversions go to directory /home/sim and follow the directions for switching M&C versions. Note this allows one to switch versions of Sparrow to the default version, i.e., the version having the same version name as the Ygor version.

To switch the version of Sparrow independently of Ygor, one must change the link sparrow in /home/sim with the following two commands:

    rm sparrow

then ln -s <fully qualified path to your sparrow folder>, i.e.,

    ln -s /home/sandboxes/developer/sparrow_home/sandbox_version sparrow

and then restart all of the python daemons, i.e., ns, es, turtle.d, gbstatus.d, AntennaCharacterization, Inclinometer, and ifpath_pickler. NOTE: This may be done by running RestartSimTurtle as user monctrl. DON'T use RestartTurtle!

Deficits

• The LO1Coordinator does not forward its routing information to the IFManager causing errant messages.
• Accessor regularly loses it connection to the Transporter on the same host.

Background

The original MR describing the goals and plan of work is here.

-- MarkClark - 21 Dec 2004