fix: 清理PLC断开后的串口会话

app/src/infrastructure/plc_communication_service.cpp

@@ -101,6 +101,11 @@ PlcCommunicationResult PlcCommunicationService::connectDevice(
     {
         return {false, "必须填写串口端口，并将 PLC 站号设置为 1~247"};
     }
+    if (state_ == PlcConnectionState::Disconnected
+        && master_->state() != QModbusDevice::UnconnectedState)
+    {
+        closeSerialSession();
+    }
     if (master_->state() != QModbusDevice::UnconnectedState)
     {
         return {false, "PLC 连接已经启动，请先断开当前连接"};
@@ -134,9 +139,12 @@ PlcCommunicationResult PlcCommunicationService::connectDevice(
     setState(PlcConnectionState::Connecting);
     if (!master_->connectDevice())
     {
-        const QModbusDevice::Error error = master_->error() == QModbusDevice::NoError
-            ? QModbusDevice::ConnectionError : master_->error();
-        handleModbusError(error);
+        if (last_error_.empty())
+        {
+            const QModbusDevice::Error error = master_->error() == QModbusDevice::NoError
+                ? QModbusDevice::ConnectionError : master_->error();
+            handleModbusError(error);
+        }
         return {false, last_error_};
     }
     return {true, {}};
@@ -144,21 +152,12 @@ PlcCommunicationResult PlcCommunicationService::connectDevice(
 
 void PlcCommunicationService::disconnectDevice()
 {
-    ++connection_generation_;
-    disconnecting_ = true;
-    poll_timer_.stop();
-    master_->disconnectDevice();
-    pending_reply_ = nullptr;
-    poll_update_pending_ = false;
-    pending_poll_addresses_.clear();
-    serial_session_opened_ = false;
-    received_valid_response_ = false;
+    closeSerialSession();
     repository_.invalidate();
     updateInitialReadCompleted(false, true);
     last_error_type_ = PlcCommunicationError::None;
     last_error_.clear();
     setState(PlcConnectionState::Disconnected);
-    disconnecting_ = false;
 }
 
 void PlcCommunicationService::setPollAddresses(
@@ -477,6 +476,23 @@ void PlcCommunicationService::handleModbusError(QModbusDevice::Error error)
     setError(classifyPlcCommunicationError(error, context));
 }
 
+void PlcCommunicationService::closeSerialSession()
+{
+    ++connection_generation_;
+    disconnecting_ = true;
+    poll_timer_.stop();
+    pending_reply_ = nullptr;
+    poll_update_pending_ = false;
+    pending_poll_addresses_.clear();
+    if (master_->state() != QModbusDevice::UnconnectedState)
+    {
+        master_->disconnectDevice();
+    }
+    serial_session_opened_ = false;
+    received_valid_response_ = false;
+    disconnecting_ = false;
+}
+
 void PlcCommunicationService::setState(PlcConnectionState state)
 {
     if (state_ == state)
@@ -502,7 +518,7 @@ void PlcCommunicationService::setError(const PlcCommunicationFailure &failure)
         || failure.type == PlcCommunicationError::UsbSerialAdapterRemoved;
     if (disconnected)
     {
-        serial_session_opened_ = false;
+        closeSerialSession();
     }
     setState(disconnected
         ? PlcConnectionState::Disconnected : PlcConnectionState::Faulted);

app/src/infrastructure/plc_communication_service.h

@@ -67,6 +67,7 @@ private:
     void updateInitialReadCompleted(bool completed, bool force_notification = false);
     void handleUnexpectedDisconnect();
     void handleModbusError(QModbusDevice::Error error);
+    void closeSerialSession();
     void setState(PlcConnectionState state);
     void setError(const PlcCommunicationFailure &failure);
 

app/src/ui/main_window.cpp

@@ -634,7 +634,16 @@ void MainWindow::connectPlc()
         plc_configuration_);
     if (!result.succeeded)
     {
-        showProjectResult(tr("连接 PLC"), fromUtf8(result.message), false);
+        const QString message = fromUtf8(result.message);
+        if (result.message == runtime_mode_service_.plcError())
+        {
+            statusBar()->showMessage(message, 5000);
+            QMessageBox::warning(this, tr("连接 PLC"), message);
+        }
+        else
+        {
+            showProjectResult(tr("连接 PLC"), message, false);
+        }
         return;
     }
     statusBar()->showMessage(tr("PLC 正在连接，等待首次 M/D 读取"), 5000);