How can I use QextSerialPort on two different serial ports in the same time?

In my program I want to communicate with two different com ports. From one of them I get alarm signals. This works Ok.:)
But now I try to send and receive data to a GSM terminal for sending SMS messages. I am not able to get response from the terminal to my computer.:(
Do you know if I can use QextSerialPort to communicate with several serial ports in the same program? I use QWidget as base.

Yes, You can create many instances of QExtSerialPort as You need.

I still do not get any answer from com port number two(GSMcomm). My code is like:
The constructor:

Code:

---

EikeTesten::EikeTesten(QWidget *parent) :
    QWidget(parent)
{ ....
qDebug("Creating QextSerialPort instance");
    CommPort = new QextSerialPort();
    CommPort->setPortName(QString("/dev/ttyUSB0"));
    CommPort->setDataBits(DATA_8);
    CommPort->setParity(PAR_NONE);
    CommPort->setFlowControl(FLOW_OFF);
    CommPort->setStopBits(STOP_1);
    CommPort->setBaudRate(BAUD300);
    CommPort->open();
QTimer *receiveTimer = new QTimer(this);
    connect(receiveTimer, SIGNAL(timeout()), SLOT(receiveMsg())); // receiveMsg get the message from ttyUSB0 and call saveData();
    receiveTimer->start(0);
..
}

---

in saveData:

Code:

---

{  ....
GSMcomm = new GSMkommunikasjon();
     GSMcomm -> sendAlarmSMS(text);
....}

---

in GSMkommunikasjon constructor:

Code:

---

{/*create and init communications port*/
    qDebug("Creating SMSCommPort instance");
    SMSCommPort = new QextSerialPort();
    SMSCommPort->setPortName(QString("/dev/ttyUSB1"));
    SMSCommPort->setDataBits(DATA_8);
    SMSCommPort->setParity(PAR_NONE);
    SMSCommPort->setFlowControl(FLOW_OFF);
    SMSCommPort->setStopBits(STOP_1);
    SMSCommPort->setBaudRate(BAUD19200);
    SMSCommPort->open();
    SMSCommPort->setDtr(0);
    SMSCommPort->setDtr(1);
    //SMSCommPort->close();
    //sendAlarmSMS();
 
    QTimer *receiveTimer2 = new QTimer(this);
    connect(receiveTimer2, SIGNAL(timeout()), SLOT(receiveFromSMS()));
    receiveTimer2->start(0);
}
 
in receiveFromSMS()
{
int numBytes = SMSCommPort->bytesAvailable();
 if(numBytes > 0) 
    {
      if (numBytes > 80) numBytes = 80;      
      char buff[80];
      int i = SMSCommPort->readData(buff, numBytes);
      buff[numBytes] = '\0';   
      QChar byte0 = buff[0];
      QChar byte1 = buff[1];
}}
... // But the program never receive anything
}

---

Can you please help me?

Just the basic checks...
- is the baudrate correct
- if you have a scope or so, do you see the DTR line toggling when you open the port ?
- try to connect something else to that port and see if that works
- put a loopback wire on the port (connect RX and TXT) and then send something in your program. It should be received back

Regards,
Marc

Hi,

Maybe it's not the matter, but it seems to me that you start 2 timers with a 0 interval time.
Is it correct? Your CPU should run at full charge, maybe that cause some trouble in the reception? Have you try with a reasonable time interval (250ms for instance)?

Loopback the wire can tell you if you're wrong on the protocol/in the serial configuration or if it's a software problem.

Thank you for your feedback:). I have tried to change the GSM terminal with something other, and then I got some input. The baudrate is correct. So something in my code is a little tricky:(.
I will check the timers:)