6. GDA Demo

6.1. Basic commands

To get help:

help

scannable = software abstraction of angles, slits, energy, temperature probe, detector...

pos – show current positions of all scannables

e.g. pos x, pos y, pos z

shows extended syntax – no brackets

Move: pos x 10

ls – look at objects of certain types

e.g. ls Motor

Easy to write dummy scannables, e.g. x/y/z, for testing

6.2. Other scannables

t

shows time since initialisation

dt

shows time since last data point captured

w

waits for specified time. e.g. to wait 2 seconds:

>>>pos w 2

all single-value position so far

multi-input – can move to multi-value position – e.g. pos mi [2, 3]

multi-extra – read-only output values – e.g. pos me

can combine – mie – one input, two (read-only) outputs – pos mie 4

6.3. Default detectors

list_defaults

add_default pil

remove_default pil

6.4. Beam focusing

fwhm = full width half maximum

minimise fwhmarea = area of spot on detector in pixels

Scan to show the images being plotted:

>>> scan f 430 600 20 pil 20

To display the images: images plotted on “Data Vector” panel

to focus on region of interest:

peak2d.setRoi(50, 50, 150, 150)

6.4.1. wide scan

>>> scan f 430 600 20 pil 20 peak2d

(finds 490 as the minimum)

data plotted as it’s collected

6.4.2. finer scan

::

>>> go minval
>>> rscan f -20 20 2.5 pil 20 peak2d

(finds 482.5 as the minimum)

6.4.3. get feature details

::

>>> minval