The Coude Echelle Spectrographs (Expert Information)

Appendix C6: Complete List of Commands

Sections: Low level spectrograph commands | Control file commands | High level spectrograph control commands | Utility procedures | Setup commands | Miscellaneous commands

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Low Level Spectrograph Commands

Spectrograph Command Format

Every control command has a full and an abbreviated form. The abbreviated form is indicated by the capitals in the names listed by DISPLAY. For example, DISPLAY lists the collimator focus position as ` Col_Focus', from which the commands COL_FOCUS and CF can be inferred. This is not infallible; the short-form command to insert the beam rotator is not R (= READ) but BR (which appears in parentheses on the display).

All low-level commands are of the form:
command value [units] [apply]
where the bracketed items units and apply can be omitted.

value can take the special values MIN and MAX where it makes sense to do so.
units specifies other than default units (which are mm, degrees or ADU, RIGHT? depending on the mechanism) for value.
apply governs whether offsets are applied to the slit and echelle angles, and defaults to TRUE.

An acknowledgement is sent immediately after the request for a mechanism to move and a later asynchronous message informs the user when the movement is complete.

Exceptions to These Rules

Some low-level commands have interlocks with the slit shutter (noted in the following tables) or perform more complex actions.

  1. Slit shutter control commands await completion and confirm it by outputting a message. In addition, the Slit_Shutter OPEN command warns if the camera shutter is closed.
  2. The ECHELLE (= E) command not only drives in the requested echelle but also enables the correct one (via ECH_ENABLE) so that the appropriate echelle angles will be controlled by subsequent commands.
  3. HART_POS (= HP) not only drives the Hartmann masks as requested but in UCLES mode also ensures that the UCLES flap is in the beam.

  4. PERISCOPE and FOCAL_MODIFIER commands ( PERI and FM) expect IN or OUT parameters, and decide which periscope and focal modifier to use based on whether the central wavelength from the most recent CONFIGURE was less than or greater than 5500 Å. RED and BLUE are also acceptable parameters, and override the default values. The focal modifier commands also automatically adjust the slit width and length to maintain the same image dimensions at the detector.
Complete List of Mechanisms

The mechanisms in Table 1 take a numeric parameter and can be driven to any position between the stated limits. Any attempt to drive them out of limits will drive to the appropriate limit, stop and give a warning message.

The mechanisms in Table 2 take a keyword parameter and are driven to the position corresponding to that keyword. Keyword synonyms are shown with `='. Table 3 shows additional commands.

Table 1: Commands taking a numeric parameter
Full Name Abbrev. Minimum Maximum Units
Col_Focus cf -10.0 5.8 mm
Ech_Theta et -3.0 3.0 deg
Ech_Gamma eg -2.0 2.0 deg
Prism_Pos pp -100.0 100.0 mm
Rotator_Angle ra 0.0 360.0 deg
Slit_Width sw 0.02 10.0 mm
Slit_Length sl 2.5 40.0 mm
Slit_Angle sa -12.0 12.0 deg
Uhrf_Focus_Coarse ufc 4050 65040 ADU
Uhrf_Focus_Fine uff -100 100 ADU
Uhrf_Theta ut 5150 63550 ADU
Uhrf_Gamma ug 550 62572 ADU
Uhrf_Secoll usc 7466 61915 ADU

Table 2: Commands taking a keyword parameter
Full Name Abbrev. Values SS* Notes
ARC arc thar; quartz; laser Y
Cam_Lamp cl on; off
Cam_Shutter cs open; shut
Collimator c wide; uv
Echelle e 31; 79
Ech_Enable ee 31; 79
Focal_Modifier fm clear; red; blue; uhrf
Hartmann h in; out
Hart_Pos hp up=a; down=b
Lamp l thar; quartz; laser
Lamp_Filter1 lf1 1; 2; 3; 4; 5; 6; 7; 8 Y
Lamp_Filter2 lf2 1; 2; 3; 4; 5; 6; 7; 8 Y
Lamp_OFf lof thar; quartz Y
Lamp_On lo thar; quartz; none Y
Prism p in; out
Rotator br in; out
Slit s slit; slicer Y
Slit_filter1 sf1 1; 2; 3; 4; 5; 6; 7; 8 Y
Slit_filter2 sf2 1; 2; 3; 4; 5; 6; 7; 8 Y
Slit_Shutter ss open; shut disabled with CCD
Tv_Filter1 tf1 1; 2; 3; 4; 5; 6; 7; 8 not implimented
Tv_Filter2 tf2 1; 2; 3; 4; 5; 6; 7; 8 not implimented
TV_mirror tv wide=arc=in; slit=out Y
Uhrf_Echelle ue 1; 0
Uhrf_HartLow uhl open (0); shut (1)
Uhrf_HartUpp uhu shut (0); open (1)
Uhrf_XDisp uxd u (7); b (9); v (11); r (13) mirrors: mb (5); mr (15)
Uhrf_FocRed ufr 1e6; 6e5; 3e5
Uhrf_CamRes ucr 1e6; 6e5; 3e5 not implimented
* SS is Y if command is interlocked with the slit shutter

Table 3: Additional commands
Command Operation
ucles select UCLES mode
uhrf select UHRF mode
r command read command in default units (mm, deg)
ru command units read command in specified units (arcsec or pixels)
cancel command cancel specified action
o = ss open; disabled with CCD
k = ss shut; disabled with CCD
raw change default units from mm and deg to encoder units (ADU)
real change default units from encoder units to mm and deg
shutdown provide orderly shutdown of spectrograph

Control File Commands

Command Operation
centre [peak] Computes control file parameters for specified wavelength
use Select new current control file
list List contents of current control file
iset Change a parameter in a control file
glist List global parameters

High-level Spectrograph Control Commands

Command Operation
configure [slauto] Configure spectrograph using current control file
display [output=file] Display the current spectrograph state
trackpa (UCLES) Maintain constant position angle on sky
cancelpa (UCLES) Cancel position angle tracking
vertical (UCLES) Maintain slit verticle on sky
cancelvertical (UCLES) Cancel vertical tracking

CONFIGURE has a variety of optional keywords associated with it:
Keyword Operation To cancel
log (=default) Log each step in the setup procedure to the VAX terminal. This keyword is retained until cancelled. nolog
slauto Sets the slit length to the maximum value avoiding order overlap. This is false by default.
fmswap (=default) Swaps between the red and blue focal modifier (if in use) depending upon the central wavelength. nofmswap
hartout (=default) Causes the Hartmann assembly to be driven out of the beam.  nohartout
periswap (=default) Swaps between red and blue periscope (if in use), depending upon the central wavelength. noperiswap

Utility Procedures

ICL utility procedures can be written simply to perform sequences of spectrograph tasks. For example,
: proc name               give new procedure name
name> sf1 5                          input spectrograph commands
name> arc thar            ... until ...
name> end proc            you end the procedure entry.
... or ...
proc star
startobey (p1) (m1) echelle tv_mirror slit
startobey (p2) (m2) echelle lamp_on none
endobey (p2) (m2)
endobey (p1) (m1)
print "Mirror slide removed from beam"
print "Arc lamps turned off"
end proc
All procedures that are written by users will be saved on exit from ICL in a file called "save.icl". To load procedures defined in a previous session, simply type load save. For further details, refer to the ICL Manual. EXISTS?

Setup Commands

The setup procedures have already been discussed in some detail in Appendices C1 to C4. However, the experienced user may wish to use some of the low-level commands that are incorporated into these routines. The routines attempt to make this easier by always saying which commands they are issuing. This way it is easy to learn what is going on. The following commands may be useful.
Command Operation
deflog Define a job logical name (useful for shorthand file names)
offsets Explicitly set values for slit and echelle angle offsets
pixels Set detector and pixel sizes
setup Execute semi-automatic setup routine
showlog Show the value of a logical name

Miscellaneous Commands

There are a few commands which have not been mentioned. Some are low-level; some refer to facilities that are not yet fully commissioned; none should do any damage.
Command Operation
focpars Define parameters governing automatic focus adjustments
instparm Write ascii file "" describing spectrograph configuration
microlog Toggle logging of micro messages
xxx_power Control individual power supplies (xxx can be ag1; ag2; cam; col; ech; prism; slit)
power_up (= power_on) Issued automatically on startup
power_down (= power_off) Issued automatically on shutdown

Ray Stathakis (
Last Update: 23 March 2000