QModbusRtuSerialMaster never close on disconnect

void QModbusDevice::disconnectDevice()
{
    setState(QModbusDevice::ClosingState);
 
    //Unconnected is set by backend -> might be delayed by event loop
    close();
}

void QModbusRtuSerialMaster::close()
{
    if (state() == QModbusDevice::UnconnectedState ||
        state() == QModbusDevice::ClosingState) {
        return;
    }
 
    setState(QModbusDevice::ClosingState);
// ...
}