256daf2dde
git-svn-id: https://subversion.xor.aps.anl.gov/synApps/areaDetector/trunk@15328 dc6c5ff5-0b8b-c028-a01f-ffb33f00fc8b
204 lines
8.0 KiB
HTML
Executable File
204 lines
8.0 KiB
HTML
Executable File
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
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"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
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<html xml:lang="en" xmlns="http://www.w3.org/1999/xhtml">
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<head>
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<title>areaDetector URL driver</title>
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<meta content="text/html; charset=ISO-8859-1" http-equiv="Content-Type" />
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</head>
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<body>
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<div style="text-align: center">
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<h1>
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areaDetector URL driver</h1>
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<h2>
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October 1, 2012</h2>
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<h2>
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Mark Rivers</h2>
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<h2>
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University of Chicago</h2>
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</div>
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<h2>
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Table of Contents</h2>
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<ul>
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<li><a href="#Introduction">Introduction</a></li>
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<li><a href="#StandardNotes">Implementation of standard driver parameters</a></li>
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<li><a href="#Driver_parameters">URL specific parameters</a></li>
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<li><a href="#Unsupported">Unsupported standard driver parameters</a></li>
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<li><a href="#Configuration">Configuration</a></li>
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<li><a href="#MEDM_screens">MEDM screens</a></li>
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</ul>
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<h2 id="Introduction" style="text-align: left">
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Introduction</h2>
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<p>
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This is a driver for reading images from a URL. It can be used to read images from
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Web cameras, <a href="http://www.axis.com/">Axis video servers</a>, or simply from
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a disk file. It reads the images using <a href="http://www.graphicsmagick.org/">GraphicsMagick</a>
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and can thus read images encoded in any of the formats supported by GraphicsMagick,
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such as JPEG, TIFF, PNG, etc.
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</p>
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<p>
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The driver simply reads images from the specified URL at the rate determined by
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the AcquirePeriod. Web cameras and Axis video servers have a URL address from which
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the current image can be read. There are often several addresses for different image
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sizes.
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</p>
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<p>
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This driver inherits from <a href="areaDetectorDoc.html#ADDriver">ADDriver</a>.
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It implements many of the parameters <a href="areaDetectorDoxygenHTML/asyn_n_d_array_driver_8h.html">
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asynNDArrayDriver.h</a> and in <a href="areaDetectorDoxygenHTML/_a_d_driver_8h.html">
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ADArrayDriver.h</a>. It also implements a number of parameters that are specific
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to the URL driver.The <a href="areaDetectorDoxygenHTML/class_u_r_l_driver.html">URL
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driver class documentation</a> describes this class in detail.</p>
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<h2 id="StandardNotes" style="text-align: left">
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Implementation of standard driver parameters</h2>
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<p>
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The following table describes how the URL driver implements some of the standard
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driver parameters.</p>
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<table border="1" cellpadding="2" cellspacing="2" style="text-align: left">
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<tbody>
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<tr>
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<td align="center" colspan="3">
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<b>Implementation of Parameters in asynNDArrayDriver.h and ADDriver.h, and EPICS Record
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Definitions in ADBase.template and NDFile.template</b></td>
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</tr>
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<tr>
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<th>
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Parameter index variable</th>
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<th>
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EPICS record name</th>
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<th>
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Description</th>
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</tr>
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<tr>
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<td>
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ADAcquirePeriod</td>
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<td>
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$(P)$(R)AcquirePeriod</td>
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<td>
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This controls the period between reading images. The driver attempts to collected
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images at this rate determined by this value. NOTE: If this value is set to 0 or
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too small a value can result in the driver using 100% of the CPU and becoming unresponsive
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to EPICS.</td>
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</tr>
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</tbody>
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</table>
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<h2 id="Driver_parameters" style="text-align: left">
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URL driver specific parameters</h2>
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<p>
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The URL driver implements the following parameters in addition to those in asynNDArrayDriver.h
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and ADDriver.h.
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</p>
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<table border="1" cellpadding="2" cellspacing="2" style="text-align: left">
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<tbody>
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<tr>
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<td align="center" colspan="7">
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<b>Parameter Definitions in URLDriver.cpp and EPICS Record Definitions in URLDriver.template</b>
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</td>
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</tr>
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<tr>
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<th>
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Parameter index variable</th>
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<th>
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asyn interface</th>
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<th>
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Access</th>
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<th>
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Description</th>
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<th>
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drvInfo string</th>
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<th>
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EPICS record name</th>
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<th>
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EPICS record type</th>
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</tr>
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<tr>
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<td>
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URLName</td>
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<td>
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asynOctet</td>
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<td>
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r/w</td>
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<td>
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The name of the URL to read images from. There are 10 output records to control
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the URL name. </td>
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<td>
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URL_NAME</td>
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<td>
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$(P)$(R)URLName[1-10]<br />
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$(P)$(R)URLName_RBV</td>
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<td>
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waveform<br />
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waveform</td>
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</tr>
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</tbody>
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</table>
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<p>
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The URLs for Web cameras and video servers are typically long strings, which are
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difficult to remember and to type. Thus, for convenience there is an EPICS mbbo
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record which is used to select 1 of 10 URLs. This allows easily switching between
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cameras, etc. The mbbo menu string fields (e.g. ZRST, ONST, etc.) can be edited
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to supply a useful short description of each camera (e.g. "Sample camera"), and
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the corresponding URL waveform record will store the actual URL. Both are in save/restore.
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Note that when the mbbo menu string fields are edited then one will need to close
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the main URLDriver.adl medm screen and reopen it to see the new menu choices. This
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is due to restrictions in medm and Channel Access.
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</p>
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<h2 id="Unsupported">
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Unsupported standard driver parameters</h2>
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<p>
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The URL driver does not support many of the standard driver parameters because it
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does not provide control of image acquisition. Thus AcquireTime, binning, region
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to read out, trigger modes, etc. are not supported.</p>
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<h2 id="Configuration">
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Configuration</h2>
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<p>
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The URL driver is created with the URLDriverConfig command, either from C/C++ or
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from the EPICS IOC shell.</p>
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<pre>int URLDriverConfig(const char *portName,
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int maxBuffers, size_t maxMemory,
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int priority, int stackSize)
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</pre>
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<p>
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For details on the meaning of the parameters to this function refer to the detailed
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documentation on the URLDirverConfig function in the <a href="areaDetectorDoxygenHTML/u_r_l_driver_8cpp.html">
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URLDriver.cpp documentation</a> and in the documentation for the constructor for
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the <a href="areaDetectorDoxygenHTML/class_u_r_l_driver.html">URLDriver class</a>.
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</p>
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<p>
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There an example IOC boot directory and startup script (<a href="URLDriver_st_cmd.html">iocBoot/iocURL/st.cmd)</a>
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provided with areaDetector.
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</p>
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<h2 id="MEDM_screens" style="text-align: left">
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MEDM screens</h2>
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<p>
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The following show the MEDM screens that are used to control the URL driver. Note
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that the general purpose screen ADBase.adl can be used, but it exposes many controls
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that are not applicable to the URL driver, and lacks some fields that are important
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for the URL driver.</p>
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<p>
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<code>URLDriver.adl</code> is the main screen used to control the URL driver.
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</p>
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<div style="text-align: center">
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<h3 style="text-align: center">
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URLDriver.adl</h3>
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<img alt="URLDriver.png" src="URLDriver.png" /></div>
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<p>
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<code>URLDriverSetup.adl</code> is the screen used to configure the mbbo menu choices
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and the URL strings for up to 10 preset URLs. Note that when a new value is entered
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into any of the URL string waveform records that URL will be immediately displayed,
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even if it is not the URL currently selected in the mbbo menu.
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</p>
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<div style="text-align: center">
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<h3 style="text-align: center">
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URLDriverSetup.adl</h3>
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<img alt="URLDriverSetup.png" src="URLDriverSetup.png" /></div>
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<p>
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The following is an ImageJ viewer window looking at the URL driver connected to
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analog camera through an Axis video server.
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</p>
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<div style="text-align: center">
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<h3 style="text-align: center">
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ImageJ Viewer of URL driver with Axis video server</h3>
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<img alt="ImageJ_URLDriver.jpg" src="ImageJ_URLDriver.jpg" /></div>
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</body>
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</html>
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