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dasformat: set readout format for one DAS channel

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Purpose:

dasformat is an engineering utility for setting or querying the readout format of one channel of data-acquisition sub-system (DAsS). It does not set a corresponding format on the associated detector.

Usage:

   dasformat [-c ccd-size] [-b binning] [-w window-enable] \
             [-1 window] [2 window] [-3 window] [-4 window] \
             [-t transformation] [-p] [-d [-r] channel

where channel is a number in the range 0..7 inclusive and the command options are as follows.

-c

sets the size of the read from the detector when no windows and binning apply. ccd-size specifies the x and y sizes in pixels thus: x:y. The default value is 100:100.

-b

sets the binning factors. binning states the x and y factors thus: x:y. The default value is 1:1.

-w

enables windowing if window-enable is 1 or disables windowing if it is 0. The default is 0. Using this option does not change the size or position of any windows but determines whether the system applies those settings.

-1

sets window 1. window defines the windows size and position in pixels in the format x-size:y-size:x-origin:y-origin. The pixel grid has a row 0 and a column 0 so an origin of (0,0) aligns the window with the edge of the frame and an origin of (1,1) offsets it one pixel into the frame. The default settings for all windows are 0:0:0:0.

-2

sets window 2.

-3

sets window 3.

-4

sets window 4.

-t

sets the geometric transformation. transformation is a string of up to eight characters expressing rotations and relections:

+

means rotate 90° anti-clockwise.

-

means rotate 90° clockwise.

x

means reflect in the x axis.

y

means reflect in the y axis.

The default transformation is no transformation.

-p

(`read parameter') means that defaults are not applied and instead the stated format-adjustments are made to the format already set.

-d

dumps the DAsS' internal list of readout strips for low-level debugging.

-r

reads back the format just set. When used with -p and no other options it is a way of querying the current format without changing it.

Examples:

Define the basic size of a newly mounted detector for channel 1:

   dasformat -c1124:1124 1

Adjust the channel in the previous example: specify a 90° rotation and a reflection to get spectra with wavelength on the x-axis increasing to the right:

   dasformat -p -t "+y" 1

Query the current format:

   dasformat -p -r 1

Caveats:

Once a format is accepted by the DAsS it remains in the control-settings record until the next format-change and is restored each time the sub-system is reset or restarted.

dasformat sets a format only for the DAS channel to which it is applied. If a multi-channeled instrument is used, it is necessary to set each channel independently (the instrument may have its own version of dasformat that does this in one go). If you use dasformat to set a format and do not set the same format on the CCD controller, then all subsequent readouts will fail or will be corrupt.

This is a common error in settings windows:

   dasformat -c1124:1124 -w1 -1 1124:100:1:1 1