69 lines
2.7 KiB
HTML
69 lines
2.7 KiB
HTML
<HTML>
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<HEAD>
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<TITLE>Chopper Control</TITLE>
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</HEAD>
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<BODY>
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<H1>Chopper Control</H1>
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<P>
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Some instruments are equipped with a Dornier Chopper system running one or more choppers:
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a disk chopper and possibly a fermi chopper. In most situations the diskchopper is
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in slave mode. This means his speed is a predefined ratio of the
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speed of the fermichopper. Furthermore, there is a phase difference between
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the two choppers in order to allow for the fligh time of neutrons
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between choppers.
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</P>
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<p>
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The program handling RS-232 requests at the chopper control computer
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is rather slow. This would slow the SICS server to unacceptable
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levels, if any request would be handled through the RS-232 interface. In order
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to cope with the problem, the SICS server buffers chopper
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information. This information is updated any minute if not set otherwise.
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</p>
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<p>
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The chopper system control is divided into several distinct objects: There
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is the actual chopper controller which mainly serves for answering
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status requests. Then there are a couple of virtual motors which
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represent the four modifiable parameters of the chopper control
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system. These can be driven through the normal <a
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href="drive.htm">drive</a> command. The commands understood by the
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chopper controller object are:
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<dl>
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<DT>choco list
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<DD>prints a listing of all known chopper parameters.
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<DT>choco name
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<DD>print only the value of parameter name. Possible values for name
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can be extratcted from the list printed with choco list.
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<DT>chosta
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<DD>This command procedure prints a status listing of the chopper
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system in a nicely formatted stefan-happy form.
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</dl>
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The following virtual motor variables exist for the chopper system.
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<dL>
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<DT>fermispeed
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<DD>fermi chopper speed
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<DT>diskspeed or chopperspeed
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<DD>disk chopper speed. Note, that driving this parameter while the
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chopper system is in synchronous mode will throw an error condition.
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<DT>phase
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<DD> The phase difference between the two choppers.
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<DT>ratio
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<DD>The ratio of fermi to disk chopper speeds.
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<DT>updateintervall
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<DD>The update intervall for the buffering of chopper data. Units are
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seconds. Setting to low values here will compromise the responsiveness
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of the SICS server.
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</DL>
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Each of the variables kindly prints its current value when given as a
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command. Modifying values happens through the normal drive
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command. For instance the command:
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<pre>
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drive fermispeed 10000
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</pre>
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will drive the fermi chopper to 10000 RPM eventually and if no problem occurs.
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Please check your input carefully for all chopper commands.
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Dornier has provided no way to stop an erraneous command in its software. So, if you intend to run the chopper to 1000 RPM and mistyped it as 10000 then
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you'll wait for 20 minutes until the chopper is at speed!
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</p>
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</BODY>
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</HTML>
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