Regarding Projector Programming using QT
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@Prath said in Regarding Projector Programming using QT:
if(!serial->open(QIODevice::ReadWrite))
Does open() succeed?
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@jsulm Yes. Open succeeded. But still, the projector could not read the commands which I am sending through serial port.
@Prath You should check what write() returns and connect a slot to https://doc.qt.io/qt-5/qserialport.html#errorOccurred to see whether you get any errors.
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@Prath You should check what write() returns and connect a slot to https://doc.qt.io/qt-5/qserialport.html#errorOccurred to see whether you get any errors.
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@jsulm Could you please help me with the syntax for checking the error. I am completely new in using this.
@Prath You know how to connect a slot to a signal?
https://doc.qt.io/qt-5/signalsandslots.html -
Yeah @jsulm . We have to connect this signal [signal]void QSerialPort::errorOccurred(QSerialPort::SerialPortError error) to the slot right?
Is this correct?
void MainWindow::errorReport(QSerialPort::SerialPortError error)
{
if(error!=0)
qDebug()<<"ERROR:"<<endl<<error; // nothing printed
}connect(this->Serial,SIGNAL(error(QSerialPort::SerialPortError)),this,SLOT(errorReport(QSerialPort::SerialPortError)));
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Yeah @jsulm . We have to connect this signal [signal]void QSerialPort::errorOccurred(QSerialPort::SerialPortError error) to the slot right?
Is this correct?
void MainWindow::errorReport(QSerialPort::SerialPortError error)
{
if(error!=0)
qDebug()<<"ERROR:"<<endl<<error; // nothing printed
}connect(this->Serial,SIGNAL(error(QSerialPort::SerialPortError)),this,SLOT(errorReport(QSerialPort::SerialPortError)));
@Prath said in Regarding Projector Programming using QT:
Is this correct?
Signal is https://doc.qt.io/qt-5/qserialport.html#errorOccurred not error. Just check the documentation.
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I think it is correct @jsulm. We are catching the signal using the slot and then displaying the signal.
@Prath
You wroteconnect(this->Serial,SIGNAL(error(QSerialPort::SerialPortError)),this,SLOT(errorReport(QSerialPort::SerialPortError)));Where you have
SIGNAL(error(QSerialPort::SerialPortError))@jsulm is expectingSIGNAL(errorOccurred(QSerialPort::SerialPortError)). If what you have works, we do not understand how.If you are writing new code and would change over to the new signal/slot syntax you would presumably receive a compile-time error.
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Your MainWindow class does not have such a signal, it's one from the QSerialPort.
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When I click on the push button the function on_pushButton_clicked is called and then I call the Qserialport to check the error. I think the code is written correctly.
What's your take?
@Prath said in Regarding Projector Programming using QT:
What's your take?
Your connect is wrong: MainWindow does NOT have signal error(QSerialPort::QSerialPort), this signal is in QSerialPort, so not in "this" but in "serial".
And please do not post screen-shots, copy paste your code...
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@Prath said in Regarding Projector Programming using QT:
What's your take?
Your connect is wrong: MainWindow does NOT have signal error(QSerialPort::QSerialPort), this signal is in QSerialPort, so not in "this" but in "serial".
And please do not post screen-shots, copy paste your code...
this signal is in QSerialPort, so not in "this" but in "serial".
Is this a case where changing to new-style signal/slot syntax would generate an error for the wrong "context" variable? Or, would testing the return result from the
connect()or from https://doc.qt.io/qt-5/qmetaobject-connection.html#operator-bool in code tell the user if the connection has failed because of the wrong context? -
this signal is in QSerialPort, so not in "this" but in "serial".
Is this a case where changing to new-style signal/slot syntax would generate an error for the wrong "context" variable? Or, would testing the return result from the
connect()or from https://doc.qt.io/qt-5/qmetaobject-connection.html#operator-bool in code tell the user if the connection has failed because of the wrong context? -
If you mean use several QSerialPorts at the same time in one application then yes, no problem with that. If you mean something else, please give more details.
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If you mean use several QSerialPorts at the same time in one application then yes, no problem with that. If you mean something else, please give more details.
