75 lines
2.6 KiB
HTML
75 lines
2.6 KiB
HTML
<HTML>
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<HEAD>
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<TITLE>Automatic Updating of NeXus Files</TITLE>
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</HEAD>
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<BODY>
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<H1>Automatic Updating of NeXus Files</H1>
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<P>
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Some instruments perform measurements for quite long counting
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times. In such cases it is advisable to save the data measured so far
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to file in order to protect against hardware or software failures. To
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this purpose an automatic file upgrade manager is provided. On
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installation the automatic update object is connected wth a counting
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device through the the callback interface. This makes sure that the
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update manager is automatically notified when counting starts or
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finishes.
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</P>
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<h2>Prerequisites for Using the Automatic Update Manager</h2>
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<p>
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In order to use automatic updating, three programs must be
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provided. Each of these programs can be a script which uses the
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nxscript facility. It can also be a SICS command.
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<dl>
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<dt>startScript
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<dd>This program is supposed to write the static part of the file. It
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is called once when the file is created.
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<dt>updateScript
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<dd>This program is supposed to create and update the variable data
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elements in the NeXus file. This is called frequently.
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<dt>linkScript
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<dd>This program is supposed to create the links within the NeXus
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file. This is called once after startcript and updateScript have been
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run.
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</dl>
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</p>
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<h2>Installing Automatic Update</h2>
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<p>
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An automatic update object is installed into SICS with:
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<pre>
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updatefactory name countername
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</pre>
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name is a placeholder for the name under which SICS knows the
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automatic update object. name is available as a SICS command later on.
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countername is a placeholder for a counter
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object (counter or HM) which triggers automatic updating of NeXus
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files. This object has to support both the countable and callback
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interfaces of SICS. Suitable SICS objects include counter and
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histogram memory objects.
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</p>
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<h2>Configuring Automatic Update</h2>
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<p>
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The SICS command created with updatefactory (see above) supports a few
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parameters which allow for the configuration of the whole
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process. Parameters follow the normal SICS syntax. Futhermore there is
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a subcommand list, which lists all configuration
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parameters. Supported parameters are:
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<dl>
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<dt>startScript
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<dd>The program supposed to write the static part of the file.
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<dt>updateScript
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<dd>The program supposed to create and update the variable data
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elements in the NeXus file.
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<dt>linkScript
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<dd>This program supposed to create the links within the NeXus
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file.
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<dt>updateintervall
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<dd>The time intervall in seconds between updates. The defualt is
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1200, eg. 20 minutes.
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<dt>onoff
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<dd>can be 1 or 0. Switches automatic updates on or off. It might be usefule for
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scans to switch this off.
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</dl>
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</p>
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</BODY>
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</HTML>
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