1 files changed, 6 insertions, 1 deletions
diff --git a/src/serialbus/qmodbusrtuserialmaster.cpp b/src/serialbus/qmodbusrtuserialmaster.cpp
index 331e0ee..5a9555e 100644
--- a/src/serialbus/qmodbusrtuserialmaster.cpp
+++ b/src/serialbus/qmodbusrtuserialmaster.cpp
@@ -144,10 +144,15 @@ bool QModbusRtuSerialMaster::open()
 */
 void QModbusRtuSerialMaster::close()
 {
-    if (state() == QModbusDevice::UnconnectedState)
+    if (state() == QModbusDevice::UnconnectedState ||
+        state() == QModbusDevice::ClosingState) {
         return;
+    }
+
+    setState(QModbusDevice::ClosingState);
 
     Q_D(QModbusRtuSerialMaster);
+
     if (d->m_serialPort->isOpen())
         d->m_serialPort->close();