Multi serial port application

[veera]

Hi @aha_1980 ,
I am working for single port now ,its not able to open the port here is my code by using send pushbutton and connect()

void Dialog :: open_serialport()
{
QSerialPort serial;
QString portName = ui->port_comboBox->currentText();
qDebug() << "The portName is " << portName;
bool currentPortNameChanged = false;
QString currentPortName;
if(currentPortName != portName)
{
currentPortName = portName;
currentPortNameChanged = true;
}

if(currentPortName.isEmpty())
{
    qDebug() << "No port name specified";
}

if(currentPortNameChanged)
{
    serial.close();
    serial.setPortName(portName);
    qDebug() << "portName" << portName;

    if(!serial.open(QIODevice::ReadWrite))
    {
        qDebug() << "can not able to open the serial port";
    }
}

}
its giving error i am passing from gui ,please help me out....

[mrjj]

@veera said in multi serial port application:

void Dialog :: open_serialport()
{
QSerialPort serial; <<<< WRONG ! its local variable

make it a class member of Dialog

[veera]

@mrjj ,
just now declared a QSerialPort as data members of the dialog class in dialog.h still also i am getting same error...

here is the declaration of the QSerialPort

#ifndef DIALOG_H
#define DIALOG_H

#include <QDialog>
#include <stdio.h>
#include <QtSerialPort/QSerialPort>


namespace Ui {
class Dialog;
}

class Dialog : public QDialog
{
    Q_OBJECT

public:
    QSerialPort serial;

[mrjj]

Super
but what error ?

[veera]

can not able to open the serial port..what was the type its receiving whether its ttyS4 or /dev/ttyS4?

[veera]

@mrjj ,
I am directly assigning the portname from gui qcombox is it correct way for accessing the port name ?

[mrjj]

Hi
normally its ttyS4
for
serial->setPortName(p.name);

Did you see the sample
http://doc.qt.io/qt-5/qtserialport-terminal-example.html

Its available directly in Creator and you can use to test.

[veera]

yes i have refer that example only.....

[veera]

i have tried both the things not able to open the port .....

[mrjj]

@veera

so are you sure PC has that port ?

if using a serial usb adapter, it has other name.

If you cannot open port using the Terminal sample then
something is wrong outside Qt.

[veera]

yes having two ports only ttyS4 and ttyS5 i am not using any usb to serial converter i am directly connecting with serial port only .....i have tried terminal example its giving the permission error means sudo permission .....

[veera]

permission is denied error while opening the port in Terminal Sample...

[jsulm]

@veera What does

ls -lh /dev/ttyS4

say?

[mrdebug]

Are you in dialout group?

[veera]

i tried using this command on the qt project path also not able to open the serial ports.....

[veera]

yes i am in dialout group....

[veera]

crw-rw---- 1 root dialout 4, 68 Dec 11 13:22 /dev/ttyS4

[veera]

@jsulm said in multi serial port application:

ls -lh /dev/ttyS4

crw-rw---- 1 root dialout 4, 68 Dec 11 13:22 /dev/ttyS4

[mrdebug]

Are you sure you really have 4 serial ports? Which kind of machine have you got?
In some case, with a beaglebone board for example, you have to enable the third and fourth serial port with a special kernel parameter.

[mrjj]

Hi
Often you have to add your user to the dialout group to be allowed to use it

usermod -a -G dialout MY_USER_NAME

as @mrdebug asks/says