The General Scan Menu

Table 8.1.3 shows the general scan menu, as it has been called for an energy scan.

ONLINE> scan/energy

**Table 8.1:** The **General Scan** Menu
--- ENERGY Scan --- SPECTRA> ENERGY: 8888.016 [eV] A-Move: \| \|[eV] ------------------------------------------------------------------------------ Scan_Name: ak_0016 Generic Scan Name: ak Comment: Start: 0 [eV] Stop: 0 [eV] Delta: 0 [eV] Sample_time: 1 [Seconds] Range: NP: Scan_par: 1 Wait_time: 0. Maximum x 0 [eV] SSA: No Auto-return: (1) YES Repeats: 1 ------------------------------------------------------------------------------ Edit com-files <~.prog>before_fast_scan.gra NO <~.prog>during_fast_scan.gra NO <~.prog>after_fast_scan.gra NO ------------------------------------------------------------------------------ PF1 - Start Scan, PF2 - Continue Scan, PF4 - Exit, <Space bar> - Stop Scan KP7 - Cursor scan_name, Z - Toggle Zoom, D - Display, ^W - Refresh Screen

Table 8.1: The General Scan Menu

                           --- ENERGY Scan ---
 SPECTRA>

 ENERGY:          8888.016      [eV]          A-Move:   |               |[eV]


------------------------------------------------------------------------------
 Scan_Name:         ak_0016
 Generic Scan Name: ak
 Comment:
 Start:           0             [eV]     Stop:         0            [eV]
 Delta:           0             [eV]     Sample_time:  1            [Seconds]
 Range:                                  NP:
 Scan_par:        1                      Wait_time:    0.
 Maximum x        0             [eV]     SSA:          No
 Auto-return:     (1) YES                Repeats:      1
------------------------------------------------------------------------------
 Edit com-files
  <~.prog>before_fast_scan.gra                                      NO
  <~.prog>during_fast_scan.gra                                      NO
  <~.prog>after_fast_scan.gra                                       NO
------------------------------------------------------------------------------
 PF1 - Start Scan, PF2 - Continue Scan, PF4 - Exit, <Space bar> - Stop Scan
 KP7 - Cursor scan_name, Z - Toggle Zoom, D - Display, ^W - Refresh Screen

The explanations of the menu items:

Start
The starting point of the scan. The default is 0, the translation of start_type or the qualifier /_start.

Stop
The end point of the scan. The default is 0, the translation of stop_type or the qualifier /_stop.

Delta
The step width. The default is 0, the translation of delta_type or the qualifier /_delta.

Range
If this parameter is supplied, ONLINE calculates start and stop. The corresponding qualifier is /_range.

np
If this parameter is supplied, ONLINE calculates delta. The corresponding qualifier is /_np_scan.

repeats
The scan is n times repeated. ONLINE maintains the symbols rindex, repeat_total and repeat_flag which may be used in before_type_scan.gra or in after_type_scan.gra. Rindex is the current repeat count, repeat_total is the number of requested repeats and repeat_flag is 1, if the current scan is a repeat scan. Repeated scans requiere a generic_scan_name.

Repeated scans can be terminated with the key 't' or by setting the symbol INTERRUPT_REPEATS.

scan_name
The scan name. ONLINE creates this scan, clears it and sets its x-values to the selected positions. During the scan the x-values are set to the actual positions. The default is the translation of scan_name_type, scan_name_general or the qualifier /_scan_name. If a scan is started with an empty scan name, ONLINE chooses scan_type_date_time.

comment
A comment line. It is copied to the first comment line of scan_name.

sample_time
The sample time. The default value is 1 second, the translation of sample_time_type or the qualifier /_sample_time.

scan_par
A scan parameter, the only purpose of this parameter is to have it available in the command files. The default value is 1, the translation of scan_par_type or the qualifier /_scan_par.

wait_time
ONLINE waits wait_time seconds before it executes during_type_scan. This feature has been implemented to reduce the effect of mechanical instabilities.

ssa
A simple scan analysis on the SCAN scan_name (In case of fast scans scan_name is filled with scan_c1). The SSA is done before after_type_scan.gra is executed. The default value of the flag is 0, the translation of ssa_type or the qualifier /_ssa. The user may specify that there is no background subtraction by issuing the /_ssa_nbs=1 qualifier.

auto_return
A flag that controls whether the energy/wavelength is driven back to the original position after the scan. The default value of this flag is given by 1, auto_return_general, auto_return_type or the qualifier /_auto_return. The qualifier has the highest precedence. The options are:

0	The motors stay where they are.
1	The motors are moved back to where the were before the scan started.
2	The motor is moved to the midpoint of the SSA analysis.
3	The motor is moved to the cms of the SSA analysis.
4	The motor is moved to the peak of the SSA analysis.
5	The motor is moved back to the starting point of the scan.

Option 2, 3 and 4 are ignored, if the SSA was not successful.

maximum_x, maximum_y
These values are returned from the scan routine. It is the position of the highest point of scan_name.

before_type_scan
The command file which is executed before a scan is started. The default name is the translation of before_type_scan. If that symbol does not exist, ONLINE tries to decode before_general_scan. If that also does not exist ONLINE, chooses before_type_scan.gra.

during_type_scan
The command file that is executed at every stop. It contains a list of commands that is read once for each scan. Statement blocks (if, for, case) are not allowed in this file in order to save CPU time. If such constructs cannot be avoided, during_type_scan must call a file with a run command. Note that there is a single line if-statement. This may appear in during_type_scan.

during_type_scan may set the symbol interrupt_scan to tell online to interrupt the scan.

The default name is the translation of during_type_scan. If that symbol does not exist, ONLINE tries to decode during_general_scan. If that also does not exist ONLINE, chooses during_type_scan.gra.

after_type_scan
The command file which is executed after a scan is finished. It may evaluate the symbol interrupt_scan to decide whether the scan has come to a normal end or not.

The default name is the translation of after_type_scan. If that symbol does not exist, ONLINE tries to decode after_general_scan. If that also does not exist ONLINE, chooses after_type_scan.gra.

A scan is started by pressing PF1. If it has been interrupted, it can be continued by PF2. Pressing PF4 (Ctrl-X) exits the menu.

KP7 invokes the cursor for scan_name. If a marker is set, ONLINE prompts whether the motors should be moved to the markes position.

Supplying PF $i$

in the command line has the same effect as pressing the corresponding key.

Once a scan has been started it can be interrupted by pressing the space bar. It may take some time - in the order of a second - before the program acknowledges the keystroke. If the interrupt occurs during the execution of the code of the scan routine, ONLINE asks " Continue to scan?". The default answer is "N". The user responds with "Y", if he interrupted the scan by mistake. If the interrupt occurs when the part of the code that changes the energy is executed, ONLINE responds with "INTERRUPT: All moves stopped ...". The user is asked whether he wants the monochromator to be moved to the last consistent position. The default answer is "Y". The scan routine detects that the energy change has been interrupted and asks whether it should continue to scan: "Error in SET_VALUE, continue to scan?". The default answer is "N".

If the user wishes to edit the command files, he has to toggle the 'NO' behind the corresponding name to 'YES'.

The key 'D' forces a re-display during the scan without interrupting it. To be used together with /nodisplay.