From 6c142a234673e442561b2c050b727aa4400177d8 Mon Sep 17 00:00:00 2001
From: Thomas Vanbesien <tvanbesi@proton.me>
Date: Fri, 20 Feb 2026 14:50:39 +0100
Subject: Wire monitored property to OPC UA monitored items
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The monitored bool now calls enableMonitoring/disableMonitoring on
the Value attribute. Adds publishingInterval property (default 100ms).
Value is no longer read at init — delivered by the monitored item.
Empty 4th demo page to verify monitoring stops when navigating away.
---
 src/OpcUaMonitoredNode.cpp | 76 ++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 73 insertions(+), 3 deletions(-)

(limited to 'src/OpcUaMonitoredNode.cpp')

diff --git a/src/OpcUaMonitoredNode.cpp b/src/OpcUaMonitoredNode.cpp
index 518ddd5..1a2da86 100644
--- a/src/OpcUaMonitoredNode.cpp
+++ b/src/OpcUaMonitoredNode.cpp
@@ -7,6 +7,7 @@
 
 #include <QMetaEnum>
 #include <QOpcUaLocalizedText>
+#include <QOpcUaMonitoringParameters>
 #include <QStringList>
 
 OpcUaMonitoredNode::OpcUaMonitoredNode (QObject *parent) : QObject (parent) {}
@@ -51,6 +52,29 @@ OpcUaMonitoredNode::setMonitored (bool monitored)
     return;
   m_monitored = monitored;
   emit monitoredChanged ();
+
+  if (!m_componentComplete || !m_node)
+    return;
+
+  if (m_monitored)
+    startMonitoring ();
+  else
+    stopMonitoring ();
+}
+
+double
+OpcUaMonitoredNode::publishingInterval () const
+{
+  return m_publishingInterval;
+}
+
+void
+OpcUaMonitoredNode::setPublishingInterval (double interval)
+{
+  if (qFuzzyCompare (m_publishingInterval, interval))
+    return;
+  m_publishingInterval = interval;
+  emit publishingIntervalChanged ();
 }
 
 QVariant
@@ -122,11 +146,18 @@ OpcUaMonitoredNode::setupNode ()
            &OpcUaMonitoredNode::handleValueUpdated);
   connect (m_node, &QOpcUaNode::attributeWritten, this,
            &OpcUaMonitoredNode::handleAttributeWritten);
+  connect (m_node, &QOpcUaNode::enableMonitoringFinished, this,
+           &OpcUaMonitoredNode::handleEnableMonitoringFinished);
+  connect (m_node, &QOpcUaNode::disableMonitoringFinished, this,
+           &OpcUaMonitoredNode::handleDisableMonitoringFinished);
 
   m_node->readAttributes (
-      QOpcUa::NodeAttribute::Value | QOpcUa::NodeAttribute::DisplayName
-      | QOpcUa::NodeAttribute::Description | QOpcUa::NodeAttribute::NodeClass
-      | QOpcUa::NodeAttribute::DataType | QOpcUa::NodeAttribute::AccessLevel);
+      QOpcUa::NodeAttribute::DisplayName | QOpcUa::NodeAttribute::Description
+      | QOpcUa::NodeAttribute::NodeClass | QOpcUa::NodeAttribute::DataType
+      | QOpcUa::NodeAttribute::AccessLevel);
+
+  if (m_monitored)
+    startMonitoring ();
 }
 
 void
@@ -153,6 +184,23 @@ OpcUaMonitoredNode::teardownNode ()
     }
 }
 
+void
+OpcUaMonitoredNode::startMonitoring ()
+{
+  if (!m_node || !m_monitored)
+    return;
+  QOpcUaMonitoringParameters params (m_publishingInterval);
+  m_node->enableMonitoring (QOpcUa::NodeAttribute::Value, params);
+}
+
+void
+OpcUaMonitoredNode::stopMonitoring ()
+{
+  if (!m_node)
+    return;
+  m_node->disableMonitoring (QOpcUa::NodeAttribute::Value);
+}
+
 /* ======================================
  *  Signal handlers
  * ====================================== */
@@ -262,6 +310,28 @@ OpcUaMonitoredNode::handleAttributeWritten (QOpcUa::NodeAttribute attr,
                               : QOpcUa::statusToString (statusCode));
 }
 
+void
+OpcUaMonitoredNode::handleEnableMonitoringFinished (
+    QOpcUa::NodeAttribute attr, QOpcUa::UaStatusCode statusCode)
+{
+  if (attr != QOpcUa::NodeAttribute::Value)
+    return;
+  if (statusCode != QOpcUa::Good)
+    qWarning () << "OpcUaMonitoredNode: enableMonitoring failed for"
+                << m_nodeId << ":" << QOpcUa::statusToString (statusCode);
+}
+
+void
+OpcUaMonitoredNode::handleDisableMonitoringFinished (
+    QOpcUa::NodeAttribute attr, QOpcUa::UaStatusCode statusCode)
+{
+  if (attr != QOpcUa::NodeAttribute::Value)
+    return;
+  if (statusCode != QOpcUa::Good)
+    qWarning () << "OpcUaMonitoredNode: disableMonitoring failed for"
+                << m_nodeId << ":" << QOpcUa::statusToString (statusCode);
+}
+
 /* ======================================
  *  Write support
  * ====================================== */
-- 
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