Kermit Software

Overview | Hardware Setup | Software Setup | GUI: Main Window | GUI: Motor Control | GUI: Other Windows | Troubleshooting ]


Kermit relies on several interoperating programs to operate: These all run on the computer sauron, a Sun Ultra10. The file ~/kermit.conf in the operator account is used to configure Kermit.

The GUI provides automatic electronic logging of all exposures, motor moves, and other important events, including support for free-form user comments. This is meant to completely replace the need for taking a paper logfile during the night.

The electronics rack supports hardware coadding, in which multiple images are read from the chip and added together in hardware before being transferred to the computer. The detector can be read out into the Leach electronics at up to 32 Mpix/s (i.e. 1 MHz per channel times 32 channels). However, data can only be transferred from the Leach electronics over the fiber into the computer at 1.5 Mpix/s. A full-frame CDS image is 8 megapixels, and thus takes about 5 seconds to read into the computer. For this reason it is highly recommended to use the hardware coadding feature rather than reading many exposures to disk, particularly for shorter exposure times.

Starting the Kermit Software

On sauron, log in as operator. In an xterm, run starttraffic. This will start the traffic and leachd servers, if they are not already running. If they're already running, it will just print an error and exit without screwing anything up, so feel free to type this without worry. These programs will print diagnostic output to this xterm as they run, so leave this window open somewhere.

In a different xterm, run kermitui. This will start the graphical user interface and initialize the camera hardware.

Also start ds9. New images will be automatically displayed in ds9 as they are taken.
Note: Sometimes the ds9 process hangs. If this happens, run fixds9 to kill the hung one and start a new ds9.

GUI: Main Window

The controls in the main window are grouped loosely as follows. At the bottom of the window are text entry boxes for the FITS file headers and log files. At the top left of the window are the most frequently used settings and the actual Expose button, while to the top right are less frequently changed settings relating to array readout.

Each entry field in the GUI is associated with one of the [Set] buttons, usually adjacent to it. When you make changes to any of the values in the GUI, the appropriate set button will change color to indiate that changes have been made but not yet taken effect. Press the [Set] buttons to apply changes. The two large [Set] buttons are equivalent; both apply all array readout configuration settings - there are two just for convenience. A button or field will turn red to get your attention if it is critical that a parameter be set, or if there is a problem with the selected options.

Exposures are controlled by four buttons, as follows:

The exposure settings you can control are as follows:

The data disk status (space available, usage, etc.) is shown at the bottom of the window. You can update this information by pressing the Update button.

Note: All data are automatically logged to a file called logsheetYYMMDD (e.g. logsheet010816). A new logsheet is created with a new date only when kermitui is stopped and restarted.

The kermitui File menu contains only two items: Source... and Quit.

The Config menu contains a number of options for kermitui: AO Communication, Sound, Set exptime sets readoutmode, Set exptime resets ncoadds/nexps, Show array power, Show Readout/Subarray Config.

GUI: Motor Control

The Motor Control window controls the filter wheel, pupil and M2 mirror slides, and detector focus stage. For each motor, the current position and a desired new position are displayed. You move the the motors to the Desired positions by pressing the Move button; one motor at a time will move into position. Stop will instantly stop all motion, but will leave the motor controller in a confused state and will require re-homing the motors before moving again. Update refreshes the display of status for each motor. This will usually happen automatically but feel free to press Update if for some reason you suspect the display is outdated.

The Filter, Pupil, M2 and Focus labels are grey when the Current and Desired filter wheel positions are the same. The labels are pink when the Current and Desired filter wheel positions are different.

The Current positions (or last recorded positions, if Status unknown) is listed for each wheel.

The Desired or next position is specified using the drop-down lists or the first three motors, and by entering a number between -8700 and 0 for the focus motor. You can home the first three motors by selecting Home from the list. To home the focus stage, choose "HomeFocus" from the Config menu (see below).

The Config menu has a few additional motor-related commands and settings.

GUI: Exposure Palette

The Exposure Palette lists a number of standard exposure times in milliseconds and number of reads. When you click on an exposure time it updates the information in the main ircalui window. The numbers to the right of each button are the number of images (including number of coadds) taken with that exposure time and number of reads. When you input a custom exposure mode, it will be added to the exposure palette automatically after its first use.

The buttons are labelled using a unique identifying string for each exposure mode, known as the "mode string". The format of a Kermit mode string is as follows:

If NReads and NResets are their default values of 1, they are not shown in the exposure palette.

The exposure palette is sorted by subarray size then exposure time.

GUI: Dark Widget

The Dark Widget looks at what exposures have been taken on the Exposure Palette and calculates how long it will take to do 10 darks of 10 coadds of each exposure type. You can modify the number of darks and number of coadds until you reach an acceptible total time for the darks (most observers try to pare down the list of dark exposures so they take less than three hours of darks). Make sure the filter wheels are in the Dark position (motor - Config - Dark). Then press Go and it will start a script for taking the specified dark images.

GUI: Analog Offsets

The readout electronics apply an offset to the voltage read from the detector before digitizing that voltage. The purpose of this is to ensure that the voltage swing is located within the bounds of the -10 V to 0 V input range of the ADCs. The necessary offset to achieve this depends on detector readout mode, pixel clocking time, and detector temperature. The Analog offsets window allows you to set these offsets.

Once you've set the offsets as desired, press the Set button to apply the changes to the detector. You can load one of three default sets of offsets by pressing the "Fast", "Slow", or "Warm" buttons. These load offsets appropriate for readouts at 4 us, 2 us, and 4us with the detector at room temperature.

The offsets for each of the 32 readout channels can be edited individually. You can also set all the offsets to one value using the Change All button. Enter a value in the input field next to the button and then press it.

The best way to determine reasonable offsets is to put the detector in single read exposure mode. Take an exposure and examine it in ds9. If the exposure is uniformly 0, the offsets need to be raised. If the exposure is uniformly 65535, the offsets need to be lowered.

This page last modified by Marshall on 2004 March 03.