--- a/qtserialbus/src/serialbus/qmodbusrtuserialmaster_p.h.orig	Tue Aug 09 12:17:42 2016
+++ b/qtserialbus/src/serialbus/qmodbusrtuserialmaster_p.h	Tue Aug 09 12:09:53 2016
@@ -80,9 +80,6 @@
     {
         Q_Q(QModbusRtuSerialMaster);
 
-        m_sendTimer.setSingleShot(true);
-        QObject::connect(&m_sendTimer, &QTimer::timeout, q, [this]() { processQueue(); });
-
         m_responseTimer.setSingleShot(true);
         QObject::connect(&m_responseTimer, &QTimer::timeout, q, [this]() { processQueue(); });
 
@@ -151,7 +148,6 @@
                 return;
             }
 
-            m_sendTimer.stop();
             m_responseTimer.stop();
             processQueueElement(response, m_current);
 
@@ -208,17 +204,20 @@
                 qCDebug(QT_MODBUS) << "(RTU server) Unhandled QSerialPort error" << error;
                 break;
             }
+            if (m_state == Send)
+                processQueue();
         });
 
         QObject::connect(m_serialPort, &QSerialPort::bytesWritten, q, [this](qint64 bytes) {
             m_current.bytesWritten += bytes;
+            if (m_current.bytesWritten >= m_current.adu.size())
+                processQueue();
         });
 
         QObject::connect(m_serialPort, &QSerialPort::aboutToClose, q, [this]() {
             Q_Q(QModbusRtuSerialMaster);
             if (q->state() != QModbusDevice::ClosingState)
                 q->close();
-            m_sendTimer.stop();
             m_responseTimer.stop();
         });
     }
@@ -283,7 +282,6 @@
 
     void processQueue()
     {
-        Q_ASSERT_X(!m_sendTimer.isActive(), "processQueue", "send timer active");
         Q_ASSERT_X(!m_responseTimer.isActive(), "processQueue", "response timer active");
 
         auto writeAdu = [this]() {
@@ -291,9 +289,6 @@
             m_current.bytesWritten = 0;
             m_current.numberOfRetries--;
             m_serialPort->write(m_current.adu);
-            // Example: 9600 baud, 11 bit per packet -> 872 char/sec
-            // so: 1000 ms / 872 char = 1.147 ms/char * 3.5 character
-            m_sendTimer.start((1000. / (qreal(m_baudRate) / 11.)) * m_current.adu.size());
 
             qCDebug(QT_MODBUS) << "(RTU client) Sent Serial PDU:" << m_current.requestPdu;
             qCDebug(QT_MODBUS_LOW).noquote() << "(RTU client) Sent Serial ADU: 0x" + m_current.adu
@@ -383,7 +378,6 @@
         return false;
     }
 
-    QTimer m_sendTimer;
     QTimer m_responseTimer;
 
     QueueElement m_current;