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opening of serial port

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  • N Offline
    N Offline
    Nimika
    wrote on last edited by
    #1

    how to open the serial port outside Qt?
    I have written my code in qt, it is opening but whenver I am writing or reading in that port its showing device not open.
    Is there any solution??
    I am using MOXA card for serial communication.

    jsulmJ 1 Reply Last reply
    0
    • N Nimika

      how to open the serial port outside Qt?
      I have written my code in qt, it is opening but whenver I am writing or reading in that port its showing device not open.
      Is there any solution??
      I am using MOXA card for serial communication.

      jsulmJ Offline
      jsulmJ Offline
      jsulm
      Lifetime Qt Champion
      wrote on last edited by jsulm
      #2

      @Nimika "it is opening but whenver I am writing or reading in that port its showing device not open" - are you sure you opened the port? Did you check it like this:

      qDebug() << serial.open(QIODevice::ReadWrite);
      

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

      N 1 Reply Last reply
      0
      • jsulmJ jsulm

        @Nimika "it is opening but whenver I am writing or reading in that port its showing device not open" - are you sure you opened the port? Did you check it like this:

        qDebug() << serial.open(QIODevice::ReadWrite);
        
        N Offline
        N Offline
        Nimika
        wrote on last edited by VRonin
        #3

        @jsulm
        i just checked it and it is showing false.
        I wrote this program.

        #include <QCoreApplication>
        #include <QSerialPort>
        #include <QDebug>
        
        QSerialPort serial;
        int main(int argc, char *argv[])
        {
            QCoreApplication a(argc, argv);
            serial.setPortName("ttyM");
            serial.setBaudRate(QSerialPort::Baud115200);
            serial.setDataBits(QSerialPort::Data8);
            serial.setStopBits(QSerialPort::OneStop);
            serial.setParity(QSerialPort::NoParity);
            serial.setFlowControl(QSerialPort::NoFlowControl);
           serial.open(QIODevice::ReadWrite);
           qDebug() << "port connected";
           qDebug() << serial.open(QIODevice::ReadWrite);
           serial.write("hello");
        QByteArray bb = serial.readAll();
        qDebug() << bb ;
           serial.close();
            return a.exec();
        }
        
        1 Reply Last reply
        0
        • N Offline
          N Offline
          Nimika
          wrote on last edited by
          #4

          @jsulm
          where am I lacking I don't understand.
          Or maybe this is the problem in MOXA port.

          jsulmJ 2 Replies Last reply
          0
          • N Nimika

            @jsulm
            where am I lacking I don't understand.
            Or maybe this is the problem in MOXA port.

            jsulmJ Offline
            jsulmJ Offline
            jsulm
            Lifetime Qt Champion
            wrote on last edited by
            #5

            @Nimika
            That's wrong:

            serial.open(QIODevice::ReadWrite);
            qDebug() << "port connected";
            qDebug() << serial.open(QIODevice::ReadWrite);
            

            do it like this (do not call open twice!):

            qDebug() << "port connected";
            qDebug() << serial.open(QIODevice::ReadWrite);
            

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

            1 Reply Last reply
            1
            • N Nimika

              @jsulm
              where am I lacking I don't understand.
              Or maybe this is the problem in MOXA port.

              jsulmJ Offline
              jsulmJ Offline
              jsulm
              Lifetime Qt Champion
              wrote on last edited by
              #6

              @Nimika If it still not able to open the connection then check all the connection parameters you're specifying.

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

              N 1 Reply Last reply
              0
              • N Offline
                N Offline
                Nimika
                wrote on last edited by
                #7

                Ok but still it is not working when I am using the single open function.

                mrjjM 1 Reply Last reply
                0
                • N Nimika

                  Ok but still it is not working when I am using the single open function.

                  mrjjM Offline
                  mrjjM Offline
                  mrjj
                  Lifetime Qt Champion
                  wrote on last edited by
                  #8

                  @Nimika
                  Hi are you 100% sure about portname ?
                  serial.setPortName("ttyM");
                  I would expect a number ttyM0

                  N 1 Reply Last reply
                  0
                  • mrjjM mrjj

                    @Nimika
                    Hi are you 100% sure about portname ?
                    serial.setPortName("ttyM");
                    I would expect a number ttyM0

                    N Offline
                    N Offline
                    Nimika
                    wrote on last edited by
                    #9

                    @mrjj
                    Oh sorry by mistake I have written that but I am using ttyM0 only.

                    mrjjM 1 Reply Last reply
                    1
                    • N Nimika

                      @mrjj
                      Oh sorry by mistake I have written that but I am using ttyM0 only.

                      mrjjM Offline
                      mrjjM Offline
                      mrjj
                      Lifetime Qt Champion
                      wrote on last edited by
                      #10

                      @Nimika
                      Ok. Just checking.

                      Did you try with minicom or any other serial programs if it will open it ?

                      N 1 Reply Last reply
                      0
                      • mrjjM mrjj

                        @Nimika
                        Ok. Just checking.

                        Did you try with minicom or any other serial programs if it will open it ?

                        N Offline
                        N Offline
                        Nimika
                        wrote on last edited by
                        #11

                        @mrjj
                        Its not working with any case.

                        mrjjM 1 Reply Last reply
                        0
                        • N Nimika

                          @mrjj
                          Its not working with any case.

                          mrjjM Offline
                          mrjjM Offline
                          mrjj
                          Lifetime Qt Champion
                          wrote on last edited by
                          #12

                          @Nimika

                          Well if minicom or friends dont like it either, my guess would be

                          Its brand new, you never gave anyone (user) permissions to ttyMX

                          its a monday one and broken :)

                          1 Reply Last reply
                          0
                          • jsulmJ jsulm

                            @Nimika If it still not able to open the connection then check all the connection parameters you're specifying.

                            N Offline
                            N Offline
                            Nimika
                            wrote on last edited by Nimika
                            #13

                            @jsulm
                            Well I have checked all the specifications still let me check it again.

                            @mrjj
                            What do you mean by "monday one and broken"??
                            Please clarify it thank you.

                            jsulmJ 1 Reply Last reply
                            0
                            • N Nimika

                              @jsulm
                              Well I have checked all the specifications still let me check it again.

                              @mrjj
                              What do you mean by "monday one and broken"??
                              Please clarify it thank you.

                              jsulmJ Offline
                              jsulmJ Offline
                              jsulm
                              Lifetime Qt Champion
                              wrote on last edited by
                              #14

                              @Nimika "made on Monday" :-)
                              Usually people are not fully operable on Monday after weekend and do more mistakes and produce more broken products :-)

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

                              N 1 Reply Last reply
                              1
                              • jsulmJ jsulm

                                @Nimika "made on Monday" :-)
                                Usually people are not fully operable on Monday after weekend and do more mistakes and produce more broken products :-)

                                N Offline
                                N Offline
                                Nimika
                                wrote on last edited by
                                #15

                                @jsulm
                                Lol!
                                but I think I am nowhere lacking in this regard.

                                1 Reply Last reply
                                0
                                • SGaistS Offline
                                  SGaistS Offline
                                  SGaist
                                  Lifetime Qt Champion
                                  wrote on last edited by SGaist
                                  #16

                                  Hi,

                                  Looks like you're on linux, wouldn't that be /dev/ttyM0 ?

                                  One other thing: do you have the rights to access the serial port ?

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

                                  1 Reply Last reply
                                  1
                                  • N Offline
                                    N Offline
                                    Nimika
                                    wrote on last edited by
                                    #17

                                    Hello all thank you for your replies.
                                    I sorted out my problem, its there in installation.
                                    Now all ports are working fine.

                                    @SGaist
                                    Yeah I have used /dev/ttyM0 only.
                                    Thank you!

                                    1 Reply Last reply
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