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[PLEASE HELP] how to make a barcode receiver?

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  • JKSHJ JKSH

    @davidlabib said in [PLEASE HELP] how to make a barcode receiver?:

    is it must came from serial port not usb?

    Qt Serial Port works with serial ports. A USB port is not a serial port.

    If your computer doesn't have a serial port, you can use a USB-to-serial converter.

    raven-worxR Offline
    raven-worxR Offline
    raven-worx
    Moderators
    wrote on last edited by
    #34

    @JKSH said in [PLEASE HELP] how to make a barcode receiver?:

    Qt Serial Port works with serial ports. A USB port is not a serial port.

    thats not true. Of course QtSerialPort works with USB.
    USB = Universal Serial Bus

    The code above i've posted definitively works with a USB Barcode scanner and i used it myself already.

    --- SUPPORT REQUESTS VIA CHAT WILL BE IGNORED ---
    If you have a question please use the forum so others can benefit from the solution in the future

    K 1 Reply Last reply
    1
    • raven-worxR raven-worx

      @davidlabib
      use the very first code (RS232).
      Then check the COM port of the scanner it is connected to (e.g. on Windows in the Device Manager).

      in your .pro file add QT += serialport

      QSerialPort example usage:

      QSerialPort* port = new QSerialPort( this );
      port->setBaudRate( QSerialPort::Baud115200 ); // possible something else, also check the manual
      port->setPort( QPortInfo("COM4") ); // COM port - check Device Manager for connected port
      if( port->open(QSerialPort::ReadOnly) )
      {
              connect(port, &QSerialPort::readyRead, this, [port]() {
                    if( !port->bytesAvailable() )
                         return;
                    const QByteArray scannedData = port->readAll();
                    // ...
              });
      }
      else
      {
          // check port->error()
      }
      
      ? Offline
      ? Offline
      A Former User
      wrote on last edited by
      #35

      @raven-worx
      0_1534947972491_3255bdcc-2942-41cb-986a-e4f1bb6adf9c-image.png
      I'm using ubuntu now

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      • SGaistS Offline
        SGaistS Offline
        SGaist
        Lifetime Qt Champion
        wrote on last edited by
        #36

        Hi,

        It's QSerialPortInfo.

        Interested in AI ? www.idiap.ch
        Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

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        • ? Offline
          ? Offline
          A Former User
          wrote on last edited by
          #37

          0_1534969744372_9c1d0188-4bd4-47a2-9e26-5799df5452cc-image.png

          i dosn't do any thing it always execute "else"
          QSerialPort::SerialPortError(DeviceNotFoundError)

          JKSHJ 1 Reply Last reply
          0
          • SGaistS Offline
            SGaistS Offline
            SGaist
            Lifetime Qt Champion
            wrote on last edited by
            #38

            And what is the error ?

            Interested in AI ? www.idiap.ch
            Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

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            • raven-worxR raven-worx

              @JKSH said in [PLEASE HELP] how to make a barcode receiver?:

              Qt Serial Port works with serial ports. A USB port is not a serial port.

              thats not true. Of course QtSerialPort works with USB.
              USB = Universal Serial Bus

              The code above i've posted definitively works with a USB Barcode scanner and i used it myself already.

              K Offline
              K Offline
              kuzulis
              Qt Champions 2020
              wrote on last edited by
              #39

              @raven-worx said in [PLEASE HELP] how to make a barcode receiver?:

              thats not true. Of course QtSerialPort works with USB.
              USB = Universal Serial Bus

              What? QtSerialPort works only with serial ports. It has nothing common with USB... Please don't confuse peoples. ;)

              1 Reply Last reply
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              • ? A Former User

                0_1534969744372_9c1d0188-4bd4-47a2-9e26-5799df5452cc-image.png

                i dosn't do any thing it always execute "else"
                QSerialPort::SerialPortError(DeviceNotFoundError)

                JKSHJ Offline
                JKSHJ Offline
                JKSH
                Moderators
                wrote on last edited by JKSH
                #40

                @davidlabib said in [PLEASE HELP] how to make a barcode receiver?:

                QSerialPort::SerialPortError(DeviceNotFoundError)

                Well, that means your program can't find a port called COM4. Read the comments in @raven-worx's code and think about what they are asking you to do.

                What is the name of the port that your scanner is connected to? https://www.cyberciti.biz/faq/find-out-linux-serial-ports-with-setserial/

                @raven-worx said in [PLEASE HELP] how to make a barcode receiver?:

                The code above i've posted definitively works with a USB Barcode scanner and i used it myself already.

                My apologies; I didn't read the codes or think of the scenario that @mrjj highlighted in his last post.

                If the barcode scanner implements RS232-over-USB, then you're right -- Qt Serial Port can indeed work with the scanner via the USB port.

                QtSerialPort works with USB.
                USB = Universal Serial Bus

                Even though they both have "serial" in their names, Universal Serial Bus is completely unrelated to old-school serial ports. The term "serial port" usually refers to an RS-232 port: https://en.wikipedia.org/wiki/Serial_port

                A USB device can be programmed to emulate serial port comms, but these are the minority. You cannot, for example, use Qt Serial Port to read your USB keyboard.

                Qt Doc Search for browsers: forum.qt.io/topic/35616/web-browser-extension-for-improved-doc-searches

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                • ? Offline
                  ? Offline
                  A Former User
                  wrote on last edited by
                  #41

                  @JKSH i didn't worked
                  i tried form com 1 to com 18
                  non of them worked

                  JKSHJ 1 Reply Last reply
                  0
                  • ? A Former User

                    @JKSH i didn't worked
                    i tried form com 1 to com 18
                    non of them worked

                    JKSHJ Offline
                    JKSHJ Offline
                    JKSH
                    Moderators
                    wrote on last edited by JKSH
                    #42

                    @davidlabib said in [PLEASE HELP] how to make a barcode receiver?:

                    @JKSH i didn't worked
                    i tried form com 1 to com 18
                    non of them worked

                    What is the name of the port that your scanner is connected to? COMX is a Windows name. Linux names are different.

                    Read https://www.cyberciti.biz/faq/find-out-linux-serial-ports-with-setserial/ to find the name on your Ubuntu machine.

                    Qt Doc Search for browsers: forum.qt.io/topic/35616/web-browser-extension-for-improved-doc-searches

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                    • ? Offline
                      ? Offline
                      A Former User
                      wrote on last edited by
                      #43

                      same error
                      i tried from ttyS0 to ttyS5 didn't work

                      JKSHJ 1 Reply Last reply
                      0
                      • ? A Former User

                        same error
                        i tried from ttyS0 to ttyS5 didn't work

                        JKSHJ Offline
                        JKSHJ Offline
                        JKSH
                        Moderators
                        wrote on last edited by JKSH
                        #44

                        @davidlabib said in [PLEASE HELP] how to make a barcode receiver?:

                        same error
                        i tried from ttyS0 to ttyS5 didn't work

                        You didn't answer my question. What is the name of the port that your scanner is connected to?

                        Also, what does QSerialPortInfo::availablePorts() give you? http://doc.qt.io/qt-5/qserialportinfo.html#availablePorts

                        Qt Doc Search for browsers: forum.qt.io/topic/35616/web-browser-extension-for-improved-doc-searches

                        ? 1 Reply Last reply
                        4
                        • JKSHJ JKSH

                          @davidlabib said in [PLEASE HELP] how to make a barcode receiver?:

                          same error
                          i tried from ttyS0 to ttyS5 didn't work

                          You didn't answer my question. What is the name of the port that your scanner is connected to?

                          Also, what does QSerialPortInfo::availablePorts() give you? http://doc.qt.io/qt-5/qserialportinfo.html#availablePorts

                          ? Offline
                          ? Offline
                          A Former User
                          wrote on last edited by A Former User
                          #45

                          @JKSH ok i could find the right port and passed from

                          if( port->open(QSerialPort::ReadOnly) )
                          

                          now I'm stuck on

                          if( !port->bytesAvailable() )
                                            return;
                          

                          it always return
                          witch mean no bytes is available

                          JKSHJ 1 Reply Last reply
                          0
                          • ? A Former User

                            @JKSH ok i could find the right port and passed from

                            if( port->open(QSerialPort::ReadOnly) )
                            

                            now I'm stuck on

                            if( !port->bytesAvailable() )
                                              return;
                            

                            it always return
                            witch mean no bytes is available

                            JKSHJ Offline
                            JKSHJ Offline
                            JKSH
                            Moderators
                            wrote on last edited by
                            #46

                            @davidlabib said in [PLEASE HELP] how to make a barcode receiver?:

                            now I'm stuck on

                            if( !port->bytesAvailable() )
                                              return;
                            

                            it always return
                            witch mean no bytes is available

                            Did you choose the correct settings? How is your scanner configured for the following?

                            • Baud rate
                            • Parity
                            • Data bits
                            • Stop bits
                            • Flow control

                            Qt Doc Search for browsers: forum.qt.io/topic/35616/web-browser-extension-for-improved-doc-searches

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                            • ? Offline
                              ? Offline
                              A Former User
                              wrote on last edited by A Former User
                              #47

                              @JKSH
                              Baud rate 115200

                              aha_1980A 1 Reply Last reply
                              0
                              • ? A Former User

                                @JKSH
                                Baud rate 115200

                                aha_1980A Offline
                                aha_1980A Offline
                                aha_1980
                                Lifetime Qt Champion
                                wrote on last edited by
                                #48

                                @davidlabib

                                I guess you don't have permission to use the serial port.

                                Please type: ls -l /dev/<your-serial-port-name> in a terminal and post the output here.

                                Qt has to stay free or it will die.

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                                1
                                • ? Offline
                                  ? Offline
                                  A Former User
                                  wrote on last edited by
                                  #49

                                  @aha_1980 yes i don't have
                                  but i use sudo

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                                  • SGaistS Offline
                                    SGaistS Offline
                                    SGaist
                                    Lifetime Qt Champion
                                    wrote on last edited by
                                    #50

                                    Don't develop as super-user.

                                    The command @aha_1980 will show the user and group affected to the device. Add your own user to that group, then log out and log in again and you will have access to the device.

                                    Interested in AI ? www.idiap.ch
                                    Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

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                                    • aha_1980A Offline
                                      aha_1980A Offline
                                      aha_1980
                                      Lifetime Qt Champion
                                      wrote on last edited by
                                      #51

                                      @davidlabib Better add your user to the group dialout and reboot your computer.

                                      Of course sudo works, but may give new problems.

                                      As @JKSH wrote, not only baudrate is important.

                                      I'd suggest to use a terminal program first to verify your scanner works correctly. Then use the same parameters for your code.

                                      Qt has to stay free or it will die.

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                                      • ? Offline
                                        ? Offline
                                        A Former User
                                        wrote on last edited by A Former User
                                        #52

                                        solved PermissionError
                                        now iam stuck in this

                                           QSerialPort* port = new QSerialPort( this );
                                           QSerialPortInfo::availablePorts();
                                           port->setBaudRate( QSerialPort::Baud115200 ); // possible something else, also check the manual
                                           port->setPort( QSerialPortInfo("ttyACM0") ); // COM port - check Device Manager for connected port
                                           QSerialPortInfo::availablePorts();
                                           if( port->open(QSerialPort::ReadOnly) )
                                           {
                                               ui->label->setText("port opended sucssefully");
                                                   connect(port, &QSerialPort::readyRead, this, [port]() {
                                                         if( !port->bytesAvailable() )
                                                             qDebug() << port->error(); ////////// I'm stuck here it seems that there is no data
                                                              return;
                                                         const QByteArray scannedData = port->readAll();
                                                         // ...
                                                   });
                                           }
                                           else
                                           {
                                               ui->label->setText("Error");
                                               qDebug() << port->error();
                                               QSerialPortInfo::availablePorts();
                                           }
                                        }
                                        

                                        also it will execute this if i clicked a button what if the user didn't click

                                        jsulmJ 1 Reply Last reply
                                        0
                                        • ? A Former User

                                          solved PermissionError
                                          now iam stuck in this

                                             QSerialPort* port = new QSerialPort( this );
                                             QSerialPortInfo::availablePorts();
                                             port->setBaudRate( QSerialPort::Baud115200 ); // possible something else, also check the manual
                                             port->setPort( QSerialPortInfo("ttyACM0") ); // COM port - check Device Manager for connected port
                                             QSerialPortInfo::availablePorts();
                                             if( port->open(QSerialPort::ReadOnly) )
                                             {
                                                 ui->label->setText("port opended sucssefully");
                                                     connect(port, &QSerialPort::readyRead, this, [port]() {
                                                           if( !port->bytesAvailable() )
                                                               qDebug() << port->error(); ////////// I'm stuck here it seems that there is no data
                                                                return;
                                                           const QByteArray scannedData = port->readAll();
                                                           // ...
                                                     });
                                             }
                                             else
                                             {
                                                 ui->label->setText("Error");
                                                 qDebug() << port->error();
                                                 QSerialPortInfo::availablePorts();
                                             }
                                          }
                                          

                                          also it will execute this if i clicked a button what if the user didn't click

                                          jsulmJ Offline
                                          jsulmJ Offline
                                          jsulm
                                          Lifetime Qt Champion
                                          wrote on last edited by
                                          #53

                                          @davidlabib said in [PLEASE HELP] how to make a barcode receiver?:

                                          qDebug() << port->error(); ////////// I'm stuck here it seems that there is no data

                                          Do you mean the slot is called but bytesAvailable() returns 0? If so what does

                                          qDebug() << port->error();
                                          

                                          print out?

                                          "also it will execute this if i clicked a button what if the user didn't click" - yes, if user does not click the button it will not be executed.

                                          https://forum.qt.io/topic/113070/qt-code-of-conduct

                                          ? 1 Reply Last reply
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