uart1 works via serial debugger, but not via UART1_TXD P9_24 pin

I Need help,
uart1 works via serial debugger, but not via UART1_TXD 24 and 26 pins,
also other UARTs not work.
Working via BEAGLEBONE BLACK SERIAL DEBUG CONNECTION is not good for me because always appeared different messages,
and i want to work only with UART1 or Uart4 on P9 Connector.

there is my code (works via serial debugger connector)

`

foreach (const QSerialPortInfo &info, QSerialPortInfo::availablePorts()) {

        QSerialPort serial;
        serial.setPort(info);
        if (serial.open(QIODevice::ReadWrite))

        {
            serial.setBaudRate(QSerialPort::Baud9600);
            serial.setDataBits(QSerialPort::Data8);
            serial.setParity(QSerialPort::NoParity);
            serial.setStopBits(QSerialPort::OneStop);
            serial.setFlowControl(QSerialPort::NoFlowControl);
            ui->label_7->setText(ui->label_7->text()+" " + serial.portName());

            serial.write("321");

            QTime dieTime= QTime::currentTime().addSecs(0.2);

            while (QTime::currentTime() < dieTime)
                QCoreApplication::processEvents(QEventLoop::AllEvents, 100);
            QByteArray data = serial.readAll();
            QString DataAsString = (QString(data.toHex()));
            dieTime= QTime::currentTime().addSecs(2);


            while (QTime::currentTime() < dieTime)
               QCoreApplication::processEvents(QEventLoop::AllEvents, 100);

           ui->label_4->setText(QString::number(serial.bytesAvailable()));


            dieTime= QTime::currentTime().addSecs(0.2);
            while (QTime::currentTime() < dieTime)
                QCoreApplication::processEvents(QEventLoop::AllEvents, 100);

            serial.close();

        }
    }

`

Any thoughts?
thanks!!!

Hi Andrey,

did you try a 3V3 connection (J1 is 5V, the other UARTs are 3V3).

Regards

All connections to the Signals on the BBB are 3v3 volts.

Yes, all. Except USB, J1, …