stop sending read requests if the interface is not connected

modbus/modbusrtumaster.cpp

@@ -77,6 +77,11 @@ bool ModbusRTUMaster::connectDevice()
     return m_modbusRtuSerialMaster->connectDevice();
 }
 
+bool ModbusRTUMaster::connected()
+{
+    return (m_modbusRtuSerialMaster->state() == QModbusDevice::State::ConnectedState);
+}
+
 void ModbusRTUMaster::setNumberOfRetries(int number)
 {
     m_modbusRtuSerialMaster->setNumberOfRetries(number);

modbus/modbusrtumaster.h

@@ -45,6 +45,7 @@ public:
     ~ModbusRTUMaster();
 
     bool connectDevice();
+    bool connected();
     void setNumberOfRetries(int number);
     void setTimeout(int timeout);
 

modbus/modbustcpmaster.cpp

@@ -71,6 +71,11 @@ bool ModbusTCPMaster::connectDevice() {
     return m_modbusTcpClient->connectDevice();
 }
 
+bool ModbusTCPMaster::connected()
+{
+    return (m_modbusTcpClient->state() == QModbusDevice::State::ConnectedState);
+}
+
 void ModbusTCPMaster::setNumberOfRetries(int number)
 {
     m_modbusTcpClient->setNumberOfRetries(number);

modbus/modbustcpmaster.h

@@ -45,6 +45,7 @@ public:
     ~ModbusTCPMaster();
 
     bool connectDevice();
+    bool connected();
     void setNumberOfRetries(int number);
     void setTimeout(int timeout);
 

modbuscommander/integrationpluginmodbuscommander.cpp

@@ -568,6 +568,9 @@ void IntegrationPluginModbusCommander::readRegister(Thing *thing)
         if (!modbus)
             return;
 
+        if (!modbus->connected())
+            return; // Send requests only if the modbus interface is connected
+
         if (thing->thingClassId() == coilThingClassId) {
             requestId = modbus->readCoil(slaveAddress, registerAddress);
         } else if (thing->thingClassId() == discreteInputThingClassId) {
@@ -583,6 +586,9 @@ void IntegrationPluginModbusCommander::readRegister(Thing *thing)
         if (!modbus)
             return;
 
+        if (!modbus->connected())
+            return; // Send requests only if the modbus interface is connected
+
         if (thing->thingClassId() == coilThingClassId) {
             requestId = modbus->readCoil(slaveAddress, registerAddress);
         } else if (thing->thingClassId() == discreteInputThingClassId) {