200 lines
6.8 KiB
HTML
200 lines
6.8 KiB
HTML
<?xml version="1.0" encoding="iso-8859-1"?>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
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"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml">
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<head>
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<meta http-equiv="content-type" content="text/html; charset=iso-8859-1" />
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<title>EPICS pva</title>
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<link rel="stylesheet" type="text/css"
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href="http://epics-pvdata.sourceforge.net/base.css" />
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<link rel="stylesheet" type="text/css"
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href="http://epics-pvdata.sourceforge.net/epicsv4.css" />
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<style type="text/css">
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/*<![CDATA[*/
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.about { margin-left: 3em; margin-right: 3em; font-size: .83em}
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table { margin-left: auto; margin-right: auto }
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.diagram { text-align: center; margin: 2.5em 0 }
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body { margin-right: 10% }
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/*]]>*/</style>
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<!-- Script that generates the Table of Contents -->
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<script type="text/javascript" src="http://epics-pvdata.sourceforge.net/script/tocgen.js"></script>
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</head>
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<body>
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<div class="head">
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<h1>EPICS pvaClientCPP</h1>
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<!-- Maturity: Working Draft or Request for Comments, or Recommendation, and date. -->
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<h2 class="nocount">EPICS V4 Working Group, Working Draft,
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26-June-2015</h2>
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<dl>
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<dt>This version:</dt>
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<dd><a
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href="pvaClientCPP.html">pvaClientCPP.html
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</a> </dd>
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<dt>Latest version:</dt>
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<dd><a
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href="pvaClientCPP_20150626.html">pvaClientCPP_20150626.html
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</a> </dd>
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<dt>Previous version:</dt>
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<dd><a
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href="easyPVA_20150609.html">easyPVA_20150609.html</a>
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</dd>
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<dt>Editors:</dt>
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<dd>Marty Kraimer, BNL</dd>
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</dl>
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<h2 class="nocount">Abstract</h2>
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<p>pvaClient is a software library that provides to an EPICS client programmer, a friendly
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client side programming interface to the data of an EPICS based control system. It is intended
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for such uses as rapid development of ad hoc programs by controls engineers, or to provide
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scientists a way to directly develop analytical applications.</p>
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<p>Specifically, pvaClient provides a synchronous interface for pvAccess, which is the
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software support for high speed controls network communications used in EPICS version 4.
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pvAccess provides a callback based interface, which can be hard to use.
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pvaClient provides an interface that does not require callbacks even for monitors.
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</p>
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pvaClientChannel provides many "convenience" methods to directly get and put
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scalar and scalarArray data types.
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Additional methods provide access to the full features of pvAccess.
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</p>
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<p>
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pvaClientMultiChannel provides access to data from multiple channels.
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It can be used directly by a client or via pvaClientMultiDouble or pvaClientNTMultiChannel.
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pvaClientMultiDouble allows the client to get and put data to multiple channels.
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But each channel must have a value field that is a numeric scalar.
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pvaClientNTMultiChannel allows the client to get and put data to multiple channels.
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Each channel must have a value field.
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The data for the channels is presented via normative type NTMultiChannel.
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</p>
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<!-- last para of Abstract is boilerplate reference to EPICS -->
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<p>For more information about EPICS generally, please refer to the home page of the <a
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href="http://www.aps.anl.gov/epics/">Experimental Physics and Industrial
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Control System</a>.</p>
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<h2 class="nocount">Status of this Document and of the pvaClient Software</h2>
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<p>pvaClientCPP is ready for use.</p>
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</div> <!-- head -->
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<div id="toc">
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<h2 class="nocount">Table of Contents</h2>
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</div>
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<!-- Place what you would like in the Table of Contents, inside the contents div -->
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<div id="contents" class="contents">
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<hr />
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<h2>Introduction</h2>
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<p>pvaClient is a synchronous API for accessing PVData via PVAccess. It provides
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an interface to many of the features provided by pvData and pvAccess.</p>
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<p>This document describes the layout of the source files in this project.</p>
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<p>
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A user overview is available via
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<a
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href="./pvaClientOverview.html">pvaClientOverview.html
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</a>
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</p>
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<p>
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Doxygen documentation is available at
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<a
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href="./html/index.html">doxygenDoc
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</a>
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</p>
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<h2>Example Database</h2>
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<p>The examples require that an example pvAccess server is runnimg.
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To get the test database go to:</p>
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<a
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href="https://github.com/epics_base/pvaClientTestCPP/blob/master/database.zip">pvaClientTestCPP/database.zip
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</a>
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Then select "raw file" and You will be able to download the zip file.
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<p>
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When unzipped this is used to create an example IOC database.
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</p>
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<p>
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After unzipping the file:
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</p>
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<pre>
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cd database/configure
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cp ExampleRELEASE.local RELEASE.local
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edit RELEASE.local
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cd ..
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make
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cd iocBoot/exampleDatabase
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../../bin/<arch:>/exampleDatabase st.cmd
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</pre>
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<h2>Examples</h2>
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<p>Examples are in directory <b>example/src</b>.
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An example of how to run them is:</p>
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<pre>
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mrk> pwd
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/home/epicsv4/pvaClientCPP/example
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mrk> bin/linux-x86_64/examplePvaClientGet
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</pre>
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<p>The following is a brief description of each example.
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In order to understand each example it
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helps to also look at the source for the example.</p>
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<h2>examplePvaClientGet</h2>
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<p>This has a number of examples:</p>
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<dl>
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<dt>exampleDouble</dt>
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<dd>
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This shows two methods for getting data from a channel that has a numeric
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scalar value field.
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</dd>
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<dt>exampleDoubleArray</dt>
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<dd>
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This shows two methods for getting data from a channel that has a
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double array value field.
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</dd>
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<dt>exampleCADouble</dt>
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<dd>
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This is like exampleDouble except it uses provider <b>ca</b>.
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</dd>
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<dt>exampleCADoubleArray</dt>
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<dd>
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This is like exampleDoubleArray except it uses provider <b>ca</b>.
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</dd>
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<dt>examplePowerSupply</dt>
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<dd>
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This is an example of getting data from a channel that does not
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have a value field.
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</dd>
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</dl>
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<h2>examplePvaClientMonitor</h2>
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<p>This is an example of creating a monitor on a channel.
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It monitors a channel that models a powerSupply, i. e. it is not a "standard" record.
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It does not have a value field.
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</p>
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<p>After starting the example a change can be made to the powerSupply by issuing:</p>
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<pre>
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pvput -r "power.value,voltage.value" examplePowerSupply 6 6
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</pre>
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<h2>examplePvaClientPut</h2>
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<p>This example gets and puts to channel exampleDouble.</p>
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<h2>examplePvaClientProcess</h2>
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<p>This example makes a process request to channel exampleDouble.</p>
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<h2>helloWorldPutGet</h2>
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<p>This is an example of issuing a channelPutGet.</p>
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<h2>examplePvaClientMultiDouble</h2>
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<p>This is an example of issuing gets and puts to multiple channels where each
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channel has a numeric scalar value field.</p>
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<h2>examplePvaClientNTMultiChannel</h2>
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<p>This is an example of using NDMultiChannel to obtain data from multiple channels.
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</p>
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<h2>helloWorldRPC</h2>
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<p>This is an example of issuing a channelRPC request.
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It does <b>not</b> use pva.</p>
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</div> <!-- class="contents" -->
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</body>
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</html>
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