an asynchronous open procedure

platform/qt/dmxwidget/dmxwidget.cpp

@@ -30,6 +30,10 @@ DmxWidget::DmxWidget(QObject *parent)
 {
   connect(this, &DmxWidget::serialDataRead, this, &DmxWidget::parseMessageBuffer);
   connect(port_, &QSerialPort::errorOccurred, this, &DmxWidget::serialErrorOccured);
+  connect(port_, &QSerialPort::readyRead, this, [this]() {
+      message_rx_buffer_.append(port_->readAll());
+      emit serialDataRead();
+  });
 }
 
 
@@ -41,46 +45,32 @@ DmxWidget::~DmxWidget()
 
 void DmxWidget::open()
 {
-  if (!port_->open(QIODeviceBase::ReadWrite))
+  auto wait_for = [this](bool &reply) {
-      return;
+    reply = false;                          // reset the reply state variale
-  ENTTEC::Widget::open();
+    for (int i = 0; i < 10; i++) {          // serial reply may not be first in the read buffer
-
+      port_->waitForReadyRead(100);         // wait for the port read buffer to have content
-  qInfo() << "Port opened on" << port_->portName();
+      if (reply)
-
+        break;                              // break the loop if a reply was received
-  getSerialNumber();
-  getParameters(0);
-  if (port_->waitForReadyRead(500) && port_->bytesAvailable() >= 19)
-  {
-    char snhead[] = {ENTTEC::Pro::START_DELIMITER,
-                     ENTTEC::Pro::OpGetWidgetSerial,
-                     0x04, 0x00}; // expect 4 bytes of message data
-    message_rx_buffer_.append(port_->readAll());
-    if (!message_rx_buffer_.startsWith(snhead))
-    {
-      message_rx_buffer_.clear();
-      close();
-      return;
     }
-    parseMessageBuffer();
+    return reply;
-  }
+  };
-  else
-  {
-    close();
-    return;
-  }
 
-  connect(port_, &QSerialPort::readyRead, this, [this]() {
+  if (!port_->open(QIODeviceBase::ReadWrite))   // open the port
-      message_rx_buffer_.append(port_->readAll());
+    return;
-      emit serialDataRead();
+  ENTTEC::Widget::open();                   // open the base class widget
-  });
+
-  emit connectedChanged(isConnected());
+  getSerialNumber();                        // request a serial number
+  getParameters(0);                         // get the metadata while we're here
+  if (wait_for(reply_serial))               // widget is found if a serial number reply is received
+    emit connectedChanged(isConnected());
+  else
+    close();
 }
 
 
 void DmxWidget::close()
 {
   port_->close();
-  disconnect(port_, &QSerialPort::readyRead, nullptr, nullptr);
   ENTTEC::Widget::close();
   emit connectedChanged(isConnected());
 }

protocol/enttec/dmx-usb-pro/widget.cpp

@@ -754,6 +754,7 @@ void Widget::rxMsgGetWidgetSerialReply(std::shared_ptr<Pro::MsgGetWidgetSerialRe
 {
   std::scoped_lock lock(mtx_metadata_);
   serial_number = msg->serial;
+  reply_serial = true;
 }
 
 

protocol/enttec/dmx-usb-pro/widget.h

@@ -125,6 +125,8 @@ protected:
   std::vector<uint8_t> user_configuration; //!< User defined configuration data.
   OperatingMode usb_mode;           //!< The side of the USB the widget is acting on.
 
+  bool reply_serial;                //!< receiving a serialnumber will set to true
+
 private:
   void rxMsgHello();
   void rxMsgReprogramFirmware();