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ICL and LDSS-2 start-up

The LDSS-2 control system runs under ICL on the instrument control computer. The commands specifically for LDSS are summarized in Table 6, and some other useful commands are shown in Table 7. The following steps are necessary to start up the system, and you will probably need to do this every day before starting to observe. It would be very wise to do this during the afternoon while there are technical staff around to correct any problems.

  1. First make sure that both the system computer and the VAXstation used to provide the user interface are running. Then log on to the VAXstation using the OBSERVER account and start up ICL by simply typing ICL. This will give you a menu of instrument combinations from which you choose LDSS. During the course of the setup, you will be asked to supply the reference focus position with respect to which all focus offsets are made (see commands LFILTER etc. below). The position must be given as an integer in the range: 0 - 767. If in doubt, set it to the centre of the allowed range, i.e. around 380. When this has finished you should have the ICL> prompt. (If for some reason the TCS was not running when ICL was started up, you will have to start up the relevant tasks with the command TEL_LINK_TO_TCS.)

  2. Normally all the LDSS-2 mechanisms are initialized automatically during the course of the startup procedures but you may need to know how to initialize LDSS-2 mechanisms in the event of problems or after loading a wheel. There are two ways to initialize LDSS-2 mechanisms depending on whether the wheels are located in a clamped position or not. After normal use they will be in such a position, but if the wheels have been loaded up recently, it is possible that they will be in an unclamped position. The significance of being in an unclamped position is twofold: (1) the position is undefined and (2) the wheel might freewheel if the telescope is not parked at the zenith which could lead to damage to some wheel-mounted components. The two ways of initialization are:

    (a)
    If you are sure that each wheel is in a clamp position, type LDSS_INIT. This will initialize each wheel in turn. On the LDSS page of the MIMIC, you should see all mechanisms turn from red to blue to green as each is initialized.

    (b)
    If you are not sure that each wheel is in a clamp position, you will need to initialize each wheel separately. Wheels which are in the clamp position may be initialized using LAPERTURE_INIT, LFILTER_INIT or LGRISM_INIT. Wheels which are not in the clamp position must be initialized with:
    SEND LDSS OBEY mechanism GINIT
    where mechanism is one of APERTURE_WHEEL, FILTER_WHEEL or GRISM_WHEEL. You must make sure that the telescope is in the zenith position otherwise there is a risk of the wheel losing registration. You can monitor progress by watching the MIMIC display.

  3. Define the contents of each wheel using:

    LAPERTURE_SETUP for the aperture wheel. You will be asked for the name of the mask to be associated with each position in the wheel.

    LFILTER_SETUP for the filter wheel. You will be asked to supply the filter name and the focus offset from the reference position, i.e. if you specify a focus offset of 0, the focus used will be the same as the reference value specified in LDSS_BEGIN or LFOCUS_SETUP unless you alter the focus independently using LFOCUS position.

    LGRISM_SETUP for the grism wheel. You will be asked for the name of the grism to be associated with each position in the wheel.

Once initialized, each wheel may be moved to a new position using the commands LAPERTURE position, LFILTER position or LGRISM position, where position is the position desired as given on the MIMIC. In principle, the name of the position as listed in the relevant ..._SETUP commands may be used, e.g. LAPERTURE 4C3729A_L1 but caution needs to be exercised since if the name is the same as a parameter name defined internally by ICL an error may result. It is safest to use the position number.

The camera focus may be changed using LFOCUS position where position is an integer in the range 0 - 767 which gives the desired focus. In normal use, the focus will be changed automatically using the focus offsets stored by LFILTER_SETUP and the fiducial focus set with LDSS_BEGIN and/or LFOCUS_SETUP.

The doors are controlled with LDOOR state where state is either 1 for locked or 0 for unlocked.

In each case the selected mechanism is indicated on the MIMIC by highlighting the selected position or displaying the chosen value.



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Wed Mar 16 00:17:46 GMT 1994