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