[PLEASE HELP] how to make a barcode receiver?

[A Former User]

@raven-worx






can you help me on setting the right mod and use QtSerialPort

[JKSH]

@davidlabib said in [PLEASE HELP] how to make a barcode receiver?:

can you help me on setting the right mod and use QtSerialPort

If you want to use Qt Serial Port, choose the RS-232 option. You will also need to connect the barcode scanner to a serial port on your computer.

[raven-worx]

@davidlabib
use the very first code (RS232).
Then check the COM port of the scanner it is connected to (e.g. on Windows in the Device Manager).

in your .pro file add QT += serialport

QSerialPort example usage:

QSerialPort* port = new QSerialPort( this );
port->setBaudRate( QSerialPort::Baud115200 ); // possible something else, also check the manual
port->setPort( QPortInfo("COM4") ); // COM port - check Device Manager for connected port
if( port->open(QSerialPort::ReadOnly) )
{
        connect(port, &QSerialPort::readyRead, this, [port]() {
              if( !port->bytesAvailable() )
                   return;
              const QByteArray scannedData = port->readAll();
              // ...
        });
}
else
{
    // check port->error()
}

[A Former User]

@JKSH is it must came from serial port not usb?

[JKSH]

@davidlabib said in [PLEASE HELP] how to make a barcode receiver?:

is it must came from serial port not usb?

Qt Serial Port works with serial ports. A USB port is not a serial port.

If your computer doesn't have a serial port, you can use a USB-to-serial converter.

[mrjj]

@JKSH
Hi
this mode, i wonder if

does not install a virtual comport and allows to use usb connection much like
serial over USB converter. just without the converter.

What do you think ? ( purely guessing here)

[raven-worx]

@JKSH said in [PLEASE HELP] how to make a barcode receiver?:

Qt Serial Port works with serial ports. A USB port is not a serial port.

thats not true. Of course QtSerialPort works with USB.
USB = Universal Serial Bus

The code above i've posted definitively works with a USB Barcode scanner and i used it myself already.

[A Former User]

@raven-worx

I'm using ubuntu now

[SGaist]

Hi,

It's QSerialPortInfo.

[A Former User]

i dosn't do any thing it always execute "else"
QSerialPort::SerialPortError(DeviceNotFoundError)

[SGaist]

And what is the error ?

[kuzulis]

@raven-worx said in [PLEASE HELP] how to make a barcode receiver?:

thats not true. Of course QtSerialPort works with USB.
USB = Universal Serial Bus

What? QtSerialPort works only with serial ports. It has nothing common with USB... Please don't confuse peoples. ;)

[JKSH]

@davidlabib said in [PLEASE HELP] how to make a barcode receiver?:

QSerialPort::SerialPortError(DeviceNotFoundError)

Well, that means your program can't find a port called COM4. Read the comments in @raven-worx's code and think about what they are asking you to do.

What is the name of the port that your scanner is connected to? https://www.cyberciti.biz/faq/find-out-linux-serial-ports-with-setserial/

@raven-worx said in [PLEASE HELP] how to make a barcode receiver?:

The code above i've posted definitively works with a USB Barcode scanner and i used it myself already.

My apologies; I didn't read the codes or think of the scenario that @mrjj highlighted in his last post.

If the barcode scanner implements RS232-over-USB, then you're right -- Qt Serial Port can indeed work with the scanner via the USB port.

QtSerialPort works with USB.
USB = Universal Serial Bus

Even though they both have "serial" in their names, Universal Serial Bus is completely unrelated to old-school serial ports. The term "serial port" usually refers to an RS-232 port: https://en.wikipedia.org/wiki/Serial_port

A USB device can be programmed to emulate serial port comms, but these are the minority. You cannot, for example, use Qt Serial Port to read your USB keyboard.

[A Former User]

@JKSH i didn't worked
i tried form com 1 to com 18
non of them worked

[JKSH]

@davidlabib said in [PLEASE HELP] how to make a barcode receiver?:

@JKSH i didn't worked
i tried form com 1 to com 18
non of them worked

What is the name of the port that your scanner is connected to? COMX is a Windows name. Linux names are different.

Read https://www.cyberciti.biz/faq/find-out-linux-serial-ports-with-setserial/ to find the name on your Ubuntu machine.

[A Former User]

same error
i tried from ttyS0 to ttyS5 didn't work

[JKSH]

@davidlabib said in [PLEASE HELP] how to make a barcode receiver?:

same error
i tried from ttyS0 to ttyS5 didn't work

You didn't answer my question. What is the name of the port that your scanner is connected to?

Also, what does QSerialPortInfo::availablePorts() give you? http://doc.qt.io/qt-5/qserialportinfo.html#availablePorts

[A Former User]

@JKSH ok i could find the right port and passed from

if( port->open(QSerialPort::ReadOnly) )

now I'm stuck on

if( !port->bytesAvailable() )
                  return;

it always return
witch mean no bytes is available

[JKSH]

@davidlabib said in [PLEASE HELP] how to make a barcode receiver?:

now I'm stuck on

if( !port->bytesAvailable() )
                  return;

it always return
witch mean no bytes is available

Did you choose the correct settings? How is your scanner configured for the following?

• Baud rate
• Parity
• Data bits
• Stop bits
• Flow control

[A Former User]

@JKSH
Baud rate 115200