db6c355f44
* added PROJECT both in HM and driver code * added single detector support. - Removed several bugs in the AMOR data bit. - Updated documentation
139 lines
6.2 KiB
HTML
139 lines
6.2 KiB
HTML
<HTML>
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<HEAD>
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<TITLE>The Internal Scan Command</TITLE>
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</HEAD>
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<BODY>
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<H1>The Internal Scan Command</H1>
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<P>
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Scans are preformed from a variety of commands in SICS. All these commands
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are just Tcl--wrappers around an internal scan object implemented in C. This
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section describes this internal scan command and how it works. This internal
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scan command is installed into the SICS server via the <a href=command.htm>MakeScanCommand
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command</a> in the initialisation file. This command install the internal
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scan object under a user defined name. For the rest of this document it is
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assumed that this name is xxscan.
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</P>
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The scan object (named here xxscan, but may have another name) understands
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the following commands:
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<DL>
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<DT>xxscan add name start step
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<DD>This command adds the variable specified by the argument name to the
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list of variables scanned in the next scan. The arguments start and step
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define the starting point and the sptep width for the scan on this variable.
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<DT>xxscan clear
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<DD>clears the list of scan variables. Must be called before each scan with
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different parameters.
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<DT>xxscan run NP mode preset
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<DD>Executes a scan. The arguments are: NP the number of scan points, mode
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the counter mode to use (this can be either timer or monitor) and preset
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which is the preset value for the counter. Scan data is written to an output
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file.
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<DT>xxscan silent NP mode preset
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<DD>Executes a scan. The arguments are: NP the number of scan points, mode
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the counter mode to use (this can be either timer or monitor) and preset
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which is the preset value for the counter. The difference to run is, that
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this scan does not produce an output file.
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<DT>xxscan recover
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<DD>Recovers an aborted scan. The scan object writes a file with all data
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necessary to continue the scan after each scan point. If for some reason a
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scan has been aborted due to user intervention or a system failure, this
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scheme allows to continue the scan when everything is alright again. This
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works only if the scan has been started with run, not with silent.
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<DT>xxscan getfile
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<DD>This command retuns the name of the current data file.
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<DT>xxscan setchannel n
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<DD>Sometimes it is required to scan not the counter but a monitor. This
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command sets the channel to collect data from. The argument n is an integer
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ID for the channel to use.
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<DT>xxscan getcounts
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<DD>Retrieves the counst collected during the scan.
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<DT>xxscan getvardata n
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<DD>This command retrieves the values of a scan variable during the scan
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(the x axis). The argument n is the ID of the scan variable to retrieve data
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for. ID is 0 for the first scan variable added, 1 for the second etc.
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<DT>xxscan interest
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<DD>A SICS client can be automatically notified about scan progress. This is
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switched on with this command. Three types of messages are sent: A string
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NewScan on start of the scan, a string ScanEnd after the scan has finished
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and a string scan.Counts = {109292 8377 ...} with the scan values after each
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finished scan point.
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<DT>xxscan uninterest
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<DD> Uninterest switches automatic notification about scan progress off.
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<DT>xxscan integrate
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<DD> Calculates the integrated intensity of the peak and the variance of teh
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intensity for the last scan. Returns either an error, when insufficient scan
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data is available or a pair of numbers. Peak integration is performed along
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the method described by Grant and Gabe in J. Appl. Cryst. (1978), 11,
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114-120.
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<DT>xxscan window [newval]
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<DD>Peak Integration uses a window in order to determine if it is still in the
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peak or in background. This command allows to request the size of this
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window (without argument) or set it (with argument giving the new window
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size).
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<DT>xxscan simscan pos FWHM height
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<DD>This is a debugging command. It simulates scan data with a hundred
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points between an x axis ranging from 10 to 20. A gauss peak is produced
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from the arguments given: pos denotes the position of the peak maximum, FWHM
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is the full width at half maximum for the peak and height is its height.
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<DT>xxscan command tclcommand
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<DD>Sets the tcl command procedure to invoke at each scan point. See below
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for the description of user defined scans. Invoked without argument command
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returns the name of the current command procedure.
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<dt>xxscan configure mode
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<dd>Confugures the several possible scan modes for the scan
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object. Currently there are two:
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<ul>
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<li><b>standard</b>, the default mode writing ASCII files.
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<li><b>amor</b>, a special mode the reflectometer AMOR which writes
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NeXus files.
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</ul>
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</DL>
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</P>
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<p>
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<h2>User Defined Scans</h2>
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<p>
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In some cases users wish to control the scan more closely, i.e. do
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multiple counting operations at the same point etc. This is especially
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true when magnets are involved. In order to do this a facility has
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been provided which allows the user to specify a macro routine which
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is called at each point. This macro routine then performs all
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necessary operations and then is responsible for storing its data. In
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order to this commands have been defined which allow to append a line
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to the scan data file and to store measured data in the scan data
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structure. The last feature is necessary in order to make scan status
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displays and scan analysis, such as center detection, work. The
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following steps are required:
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<ol>
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<li>Write a suitable macro procedure for the actions required at each
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scan point. The procedure signature looks like this:
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<pre>
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proc myScanPoint {point} {
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}
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</pre> And will be called with the number of the current scan point as
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a parameter. Besides all usual Tcl and SICS commands the following
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special commands may be used:
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<dl>
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<dt>xxxscan line text
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<dd>Appends all the text after line to the scan data file.
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<dt>xxxscan storecounts c1 c2 c3 c4 ...
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<dd>Stores the first number given as count data, all the others as
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monitor values in the internal scan data structure.
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</dl>
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<li>Test the procedure.
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<li>Switch the internal scan command command into user scan mode with
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the command:
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<b>xxxscan configure user</b>
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<li>Assign your procedure to the internal scan command with the
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command: <b>xxxscan command myScanPoint</b>
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<li>Use normal scan commands for doing your scan.
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<li>Switch the internal scan command into normal mode with the
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command:
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<B>xxxscan configure standard</b>.
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</ol>
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In all this replace xxxscan with the name of the internal scan
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command.
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</p>
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</BODY>
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</HTML>
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