QSerialPort USB-SERIAL adapter FTDI

talexcomputers

Hello,

I try to develop an application to be used with a cash register on windows using QSerialPort. Cash register is connected using USB-SERIAL adapater. I have some problems with serial port:

it call com.write(data); - the data is not send to printer until I call com.flush();
So if I must send send data to printer it won't work.
I try to read response from printer using readAll, waitForAvailable, read but all of them return nothing.

I configure com port using settings as description : baud:4800, on stop bit, no parity, no flowcontrol, port name.

The start sequence to talk with printer is : 0x11 0x11 0x30 0x31
And she would responde with a block data containing : 000000

Can you help me with any suggestion how I can get this read information from printer?

Thanks

talexcomputers

Hello,

Sorry for my late answer.
I set in in constructor
@connect(port, SIGNAL(error(QSerialPort::SerialPortError)), this, SLOT(handlePortError(QSerialPort::SerialPortError)));@

Thi is the function I call:
@connectToPort() {
port->setPortName("COM1");
port->setBaudRate(QSerialPort::Baud4800);
port->setDataBits(QSerialPort::Data8);
port->setFlowControl(QSerialPort::NoFlowControl);
port->setStopBits(QSerialPort::OneStop);
port->setParity(QSerialPort::NoParity);
if(port->open(QIODevice::ReadWrite)) {
QMessageBox::information(0,"OPEN INFO", QString::number(port->baudRate()));

        port->write(QByteArray::fromHex("FF FF FF FF FF FF FF FF FF FF 13 13 13"));
        port->flush();
        port->write(QByteArray::fromHex("FF FF FF FF FF FF FF FF FF FF 11 11 30 31 FF FF FF FF FF"));
        port->flush();

   
} else {
    QMessageBox::critical(0, "ERROR", port->errorString());
    port->close();
}

}
@

if I don't use port->flush() data is not send to port
when the function try to open port a QSerialPort::SerialPortError signal is emited and throw error Unknown error message ( but the application continues to run and show message box with baudrate

I make something wrong? Or there is a problem with
@if(port->open(QIODevice::ReadWrite))@
or the connection
@connect(port, SIGNAL(error(QSerialPort::SerialPortError)), this, SLOT(handlePortError(QSerialPort::SerialPortError)));@ ?

To mention I use USB-SERIAL FTDI adapter.

Thank you.

kuzulis

What version of QtSerialPort did you use?

talexcomputers

I'm not sure. Is version which came with with Qt 5.3.0 mingw windows binary.

kuzulis

Probably you need to open() the device at first, and then to configure it, because (as I remember) for 5.3.0 your code is wrong. It is better - to update your Qt to latest.

xmaze

change to @ QMessageBox::critical(this, tr("Error"), port->errorString());@

talexcomputers

Thank you for help. I move settings after I open com and also I change critical messagebox to show error. But the problem persist so for the moment I disable error reporting .
I success print some data on printer ( I must mention this is quite a strange printer - I must put the com->write into a loop until I get an answer from device).

I will update this night qt to last version and I will we back with more info.

Thanks a lot.

talexcomputers

Hello,

I came back with another problem.
This is code:
@
/*
This function is called from an while loop and is used to send dataToPrint from main function
*/

bool Driver::print() {

QByteArray readData;

port = new QSerialPort();
port->setPortName("COM1");
if (!port->open(QIODevice::ReadWrite) {
QMessageBox::information(0, "COM ERROR", port->errorString());
}
port->setBaudRate(QSerialPort::Baud4800);
port->DataBits(QSerialPort::Data8);
port->setStopBits(QSerialPort::OneStop);
port->setParity(QSerialPort::NoParity);
port->setFlowControl(QSerialPort::NoFlowControl);

port->write(QByteArray::fromHex("FF FF FF FF FF FF FF FF FF FF 13 13 13 FF FF FF FF FF FF"));
port->waiForBytesWritten(2);

while (1) {

port->write(QByteArray::fromHex("FF FF FF FF FF FF FF FF FF FF 11 11 30 31 FF FF FF FF FF FF"));
port->waiForBytesWritten(2);

if(port->waitForReadyRead(2)) {
dataRead.append(port->readAll());
}

if(dataRead.length >= 25) {

port->write(QByteArray::fromHex("FF FF FF FF FF FF FF FF FF FF 06 FF FF FF FF FF FF"));
port->waiForBytesWritten(2);

/*
If i put QMessageBox::information(0, "title", "bla bla"); then dataIwhistToSend is executed by
device ( but not all the time).
*/
port->write(dataIwhistToSend);
port->waiForBytesWritten(2);

break;
}
}
return true;
}

@

This is situation:
This function is called from another function which iterates an message array and send info to device ( to printed).

Cases:

1 . If i send just one message ( not more) then is working and message is printed.

2 . If i send 2 messages (one after another) the second message is not printed.

If i send 2 messages (one after another) and i put commented QMessageBox the second message sometimes get printed .
If i send a message this is printed.If i close app and edit to send second message then is printed - seems i can only print just one message when app is running.

I test with QThread but i get nothing.

I also test with QApplication::proccessEvents() in while loop but nothing.

Seems that app cand only print one message . How can i do to get printed more messages?

Any suggestions?

I use Qt 5.3.2 for windows , on win 8 pro x64. QSerialPort version is 5.2.0.