There is a problem in QserialPort Class.Who can solve it ? Recently, I designed a program based on Windows 10 with using QT5.9.

mepha

I want to Send a special terminated Command bytes to my MCU board before Closing SerialPort. When i combined send Function into a Push Button Event, actually in a Push Button Slot Fuction, My windows Program does not Send anything and serialPort is Closed at same time.
I want to send the terminated Command bytes firstly, and the serialport will be closed secondly in the same Slot.
However, i didnot get the result. Who can help me to solve it? Thank you for your any helps.

void MainWindow::System_Stop(void)
{
bool SerialPort_Status = 0;
try
{
if(SerialPort_Setting_Sucessfully_Flag == 1)
{
Stop_Flag = 1;
SerialPort_Setting_Sucessfully_Flag = 0;
}
SerialPort_Status = (char)(serialport1->write((char*)PC_CMD_Stop,10));
// Serial_Port_Close_Cnt = 0;
// while(Serial_Port_Close_Cnt < 2);
serialport1->close();

    if(timer1->isActive())
    {
        timer1->stop();
    }

    series0->clear();
    Rx_Fifo.clear();
    Start_Run_Flag = 0;
}
catch(QString exception)
{
    QMessageBox::about(this,"Error",exception);
    Start_Run_Flag = 0;
    SerialPort_Setting_Sucessfully_Flag = 0;
    return;
}

}

mepha

SerialPort_Status = (char)(serialport1->write((char*)PC_CMD_Stop,10));
my_serialport1->waitForBytesWritten();//add this
serialport1->close();

SGaist

Hi and welcome to devnet,

Are you using QSerialPort ? If so how are you initializing it ?
Why are you casting to a char the number of character written ?

You are closing your port yet in no part of the code you posted are you opening it.

mmiacca

Hi, you must wait the char is sended before close the port or try with QSerialPort::flush()

mepha

@mmiacca That is useful! thanks.

kuzulis

or try with QSerialPort::flush()

No!

you must wait the char is sended before close

Yes, it is correct. To do it, you can use bytesWritten() signal and plus some timeout.

mepha

SerialPort_Status = (char)(serialport1->write((char*)PC_CMD_Stop,10));
my_serialport1->waitForBytesWritten();//add this
serialport1->close();