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<title>QModbusRequest Class | Qt Serial Bus 5.12.6</title>
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<td >Qt 5.12</td><td ><a href="qtserialbus-index.html">Qt Serial Bus</a></td><td ><a href="qtserialbus-module.html">C++ Classes</a></td><td >QModbusRequest</td></tr></table><table class="buildversion"><tr>
<td id="buildversion" width="100%" align="right"><a href="qtserialbus-index.html">Qt 5.12.6 Reference Documentation</a></td>
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<h3><a name="toc">Contents</a></h3>
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<li class="level1"><a href="#public-types">Public Types</a></li>
<li class="level1"><a href="#public-functions">Public Functions</a></li>
<li class="level1"><a href="#static-public-members">Static Public Members</a></li>
<li class="level1"><a href="#related-non-members">Related Non-Members</a></li>
<li class="level1"><a href="#details">Detailed Description</a></li>
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<h1 class="title">QModbusRequest Class</h1>
<!-- $$$QModbusRequest-brief -->
<p><a href="qmodbusrequest.html">QModbusRequest</a> is a container class containing the function code and payload that is stored inside a Modbus ADU. <a href="#details">More...</a></p>
<!-- @@@QModbusRequest -->
<div class="table"><table class="alignedsummary">
<tr><td class="memItemLeft rightAlign topAlign"> Header:</td><td class="memItemRight bottomAlign"> <span class="preprocessor">#include <QModbusRequest></span>
</td></tr><tr><td class="memItemLeft rightAlign topAlign"> qmake:</td><td class="memItemRight bottomAlign"> QT += serialbus</td></tr><tr><td class="memItemLeft rightAlign topAlign"> Since:</td><td class="memItemRight bottomAlign"> Qt 5.8</td></tr><tr><td class="memItemLeft rightAlign topAlign"> Inherits:</td><td class="memItemRight bottomAlign"> <a href="qmodbuspdu.html">QModbusPdu</a></td></tr></table></div><ul>
<li><a href="qmodbusrequest-members.html">List of all members, including inherited members</a></li>
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<a name="public-types"></a>
<h2 id="public-types">Public Types</h2>
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<tr><td class="memItemLeft rightAlign topAlign"> typedef </td><td class="memItemRight bottomAlign"><b><a href="qmodbusrequest.html#CalcFuncPtr-typedef">CalcFuncPtr</a></b></td></tr>
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<h2 id="public-functions">Public Functions</h2>
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<tr><td class="memItemLeft rightAlign topAlign"> </td><td class="memItemRight bottomAlign"><b><a href="qmodbusrequest.html#QModbusRequest">QModbusRequest</a></b>()</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> </td><td class="memItemRight bottomAlign"><b><a href="qmodbusrequest.html#QModbusRequest-1">QModbusRequest</a></b>(const QModbusPdu &<i>pdu</i>)</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> </td><td class="memItemRight bottomAlign"><b><a href="qmodbusrequest.html#QModbusRequest-2">QModbusRequest</a></b>(QModbusPdu::FunctionCode <i>code</i>, const QByteArray &<i>data</i> = ...)</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> </td><td class="memItemRight bottomAlign"><b><a href="qmodbusrequest.html#QModbusRequest-3">QModbusRequest</a></b>(QModbusPdu::FunctionCode <i>code</i>, Args... <i>data</i>)</td></tr>
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<ul>
<li class="fn">11 public functions inherited from <a href="qmodbuspdu.html#public-functions">QModbusPdu</a></li>
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<h2 id="static-public-members">Static Public Members</h2>
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<tr><td class="memItemLeft rightAlign topAlign"> int </td><td class="memItemRight bottomAlign"><b><a href="qmodbusrequest.html#calculateDataSize">calculateDataSize</a></b>(const QModbusRequest &<i>request</i>)</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> int </td><td class="memItemRight bottomAlign"><b><a href="qmodbusrequest.html#minimumDataSize">minimumDataSize</a></b>(const QModbusRequest &<i>request</i>)</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> void </td><td class="memItemRight bottomAlign"><b><a href="qmodbusrequest.html#registerDataSizeCalculator">registerDataSizeCalculator</a></b>(QModbusPdu::FunctionCode <i>fc</i>, QModbusRequest::CalcFuncPtr <i>calculator</i>)</td></tr>
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<a name="related-non-members"></a>
<h2 id="related-non-members">Related Non-Members</h2>
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<tr><td class="memItemLeft rightAlign topAlign"> QDataStream &</td><td class="memItemRight bottomAlign"><b><a href="qmodbusrequest.html#operator-gt-gt">operator>></a></b>(QDataStream &<i>stream</i>, QModbusRequest &<i>pdu</i>)</td></tr>
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<h3>Additional Inherited Members</h3>
<ul>
<li class="fn">1 protected function inherited from <a href="qmodbuspdu.html#protected-functions">QModbusPdu</a></li>
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<a name="details"></a>
<!-- $$$QModbusRequest-description -->
<div class="descr">
<h2 id="details">Detailed Description</h2>
<p><a href="qmodbusrequest.html">QModbusRequest</a> is a container class containing the function code and payload that is stored inside a Modbus ADU.</p>
<p>A Modbus request usually consists of a single byte describing the <code>FunctionCode</code> and N bytes of payload</p>
<p>A typical Modbus request can looks like this:</p>
<pre class="cpp">
<span class="type"><a href="qmodbusrequest.html#QModbusRequest">QModbusRequest</a></span> request(<span class="type"><a href="qmodbusrequest.html#QModbusRequest">QModbusRequest</a></span><span class="operator">::</span>WriteMultipleCoils<span class="operator">,</span>
<span class="type">QByteArray</span><span class="operator">::</span>fromHex(<span class="string">"0013000a02cd01"</span>));
</pre>
<p><b>Note: </b>When using the constructor taking the <code>QByteArray</code>, please make sure to convert the containing data to big-endian byte order before creating the request.</p><p>The same request can be created like this, if the values are known at compile time:</p>
<pre class="cpp">
<span class="type">quint16</span> startAddress <span class="operator">=</span> <span class="number">19</span><span class="operator">,</span> numberOfCoils <span class="operator">=</span> <span class="number">10</span>;
<span class="type">quint8</span> payloadInBytes <span class="operator">=</span> <span class="number">2</span><span class="operator">,</span> outputHigh <span class="operator">=</span> <span class="number">0xcd</span><span class="operator">,</span> outputLow <span class="operator">=</span> <span class="number">0x01</span>;
<span class="type"><a href="qmodbusrequest.html#QModbusRequest">QModbusRequest</a></span> request(<span class="type"><a href="qmodbusrequest.html#QModbusRequest">QModbusRequest</a></span><span class="operator">::</span>WriteMultipleCoils<span class="operator">,</span> startAddress<span class="operator">,</span> numberOfCoils<span class="operator">,</span>
payloadInBytes<span class="operator">,</span> outputHigh<span class="operator">,</span> outputLow);
</pre>
</div>
<!-- @@@QModbusRequest -->
<div class="types">
<h2>Member Type Documentation</h2>
<!-- $$$CalcFuncPtr -->
<h3 class="fn" id="CalcFuncPtr-typedef"><a name="CalcFuncPtr-typedef"></a>typedef QModbusRequest::<span class="name">CalcFuncPtr</span></h3>
<p>Typedef for a pointer to a custom calculator function with the same signature as <a href="qmodbusrequest.html#calculateDataSize">QModbusRequest::calculateDataSize</a>.</p>
<!-- @@@CalcFuncPtr -->
</div>
<div class="func">
<h2>Member Function Documentation</h2>
<!-- $$$QModbusRequest[overload1]$$$QModbusRequest -->
<h3 class="fn" id="QModbusRequest"><a name="QModbusRequest"></a>QModbusRequest::<span class="name">QModbusRequest</span>()</h3>
<p>Constructs an invalid <a href="qmodbusrequest.html">QModbusRequest</a>.</p>
<!-- @@@QModbusRequest -->
<!-- $$$QModbusRequest$$$QModbusRequestconstQModbusPdu& -->
<h3 class="fn" id="QModbusRequest-1"><a name="QModbusRequest-1"></a>QModbusRequest::<span class="name">QModbusRequest</span>(const <span class="type"><a href="qmodbuspdu.html#QModbusPdu">QModbusPdu</a></span> &<i>pdu</i>)</h3>
<p>Constructs a copy of <i>pdu</i>.</p>
<!-- @@@QModbusRequest -->
<!-- $$$QModbusRequest$$$QModbusRequestQModbusPdu::FunctionCodeconstQByteArray& -->
<h3 class="fn" id="QModbusRequest-2"><a name="QModbusRequest-2"></a>QModbusRequest::<span class="name">QModbusRequest</span>(<span class="type"><a href="qmodbuspdu.html#FunctionCode-enum">QModbusPdu::FunctionCode</a></span> <i>code</i>, const <span class="type">QByteArray</span> &<i>data</i> = ...)</h3>
<p>Constructs a <a href="qmodbusresponse.html">QModbusResponse</a> with function code set to <i>code</i> and payload set to <i>data</i>. The data is expected to be stored in big-endian byte order already.</p>
<!-- @@@QModbusRequest -->
<!-- $$$QModbusRequest$$$QModbusRequestQModbusPdu::FunctionCodeArgs... -->
<h3 class="fn" id="QModbusRequest-3"><a name="QModbusRequest-3"></a>QModbusRequest::<span class="name">QModbusRequest</span>(<span class="type"><a href="qmodbuspdu.html#FunctionCode-enum">QModbusPdu::FunctionCode</a></span> <i>code</i>, <span class="type">Args</span>... <i>data</i>)</h3>
<p>Constructs a <a href="qmodbusrequest.html">QModbusRequest</a> with function code set to <i>code</i> and payload set to <i>data</i>. The data is converted and stored in big-endian byte order.</p>
<p><b>Note: </b>Usage is limited <code>quint8</code> and <code>quint16</code> only. This is because <code>QDataStream</code> stream operators will not only append raw data, but also e.g. size, count, etc. for complex types.</p><!-- @@@QModbusRequest -->
<!-- $$$calculateDataSize[overload1]$$$calculateDataSizeconstQModbusRequest& -->
<h3 class="fn" id="calculateDataSize"><a name="calculateDataSize"></a><code>[static] </code><span class="type">int</span> QModbusRequest::<span class="name">calculateDataSize</span>(const <span class="type"><a href="qmodbusrequest.html#QModbusRequest">QModbusRequest</a></span> &<i>request</i>)</h3>
<p>Calculates the expected data size for <i>request</i> based on the request's function code and data. Returns the full size of the request's data part; <code>-1</code> if the size could not be properly calculated.</p>
<p><b>See also </b><a href="qmodbusrequest.html#minimumDataSize">minimumDataSize</a> and <a href="qmodbusrequest.html#registerDataSizeCalculator">registerDataSizeCalculator</a>.</p>
<!-- @@@calculateDataSize -->
<!-- $$$minimumDataSize[overload1]$$$minimumDataSizeconstQModbusRequest& -->
<h3 class="fn" id="minimumDataSize"><a name="minimumDataSize"></a><code>[static] </code><span class="type">int</span> QModbusRequest::<span class="name">minimumDataSize</span>(const <span class="type"><a href="qmodbusrequest.html#QModbusRequest">QModbusRequest</a></span> &<i>request</i>)</h3>
<p>Returns the expected minimum data size for <i>request</i> based on the request's function code; <code>-1</code> if the function code is not known.</p>
<!-- @@@minimumDataSize -->
<!-- $$$registerDataSizeCalculator[overload1]$$$registerDataSizeCalculatorQModbusPdu::FunctionCodeQModbusRequest::CalcFuncPtr -->
<h3 class="fn" id="registerDataSizeCalculator"><a name="registerDataSizeCalculator"></a><code>[static] </code><span class="type">void</span> QModbusRequest::<span class="name">registerDataSizeCalculator</span>(<span class="type"><a href="qmodbuspdu.html#FunctionCode-enum">QModbusPdu::FunctionCode</a></span> <i>fc</i>, <span class="type"><a href="qmodbusrequest.html#CalcFuncPtr-typedef">QModbusRequest::CalcFuncPtr</a></span> <i>calculator</i>)</h3>
<p>This function registers a user-defined implementation to calculate the request data size for function code <i>fc</i>. It can be used to extend or override the implementation inside <a href="qmodbusrequest.html#calculateDataSize">QModbusRequest::calculateDataSize</a>().</p>
<p>The <code>CalcFuncPtr</code> is a typedef for a pointer to a custom <i>calculator</i> function with the following signature:</p>
<pre class="cpp">
<span class="type">int</span> myCalculateDataSize(<span class="keyword">const</span> <span class="type"><a href="qmodbusrequest.html#QModbusRequest">QModbusRequest</a></span> <span class="operator">&</span>pdu);
</pre>
<!-- @@@registerDataSizeCalculator -->
</div>
<div class="relnonmem">
<h2>Related Non-Members</h2>
<!-- $$$operator>>[overload1]$$$operator>>QDataStream&QModbusRequest& -->
<h3 class="fn" id="operator-gt-gt"><a name="operator-gt-gt"></a><span class="type">QDataStream</span> &<span class="name">operator>></span>(<span class="type">QDataStream</span> &<i>stream</i>, <span class="type"><a href="qmodbusrequest.html#QModbusRequest">QModbusRequest</a></span> &<i>pdu</i>)</h3>
<p>Reads a <i>pdu</i> from the <i>stream</i> and returns a reference to the stream.</p>
<p><b>Note: </b>The function might fail to properly stream PDU's with function code <a href="qmodbuspdu.html#FunctionCode-enum">QModbusPdu::Diagnostics</a> or <a href="qmodbuspdu.html#FunctionCode-enum">QModbusPdu::EncapsulatedInterfaceTransport</a> because of the missing size indicator inside the PDU. In particular this may happen when the PDU is embedded into a stream that doesn't end with the diagnostic/encapsulated request itself.</p><!-- @@@operator>> -->
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