[PLEASE HELP] how to make a barcode receiver?

[Pablo J. Rogina]

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

always waiting for input 13 digit --any right barcode in the world contain 13 digit

Be careful with this assumption, think of EAN 8 for instance...

Like the UPC code, there is the EAN-13 symbology with 13 digits, and an abbreviated EAN barcode called the EAN-8 with only 8 digits for smaller goods where space is limited.

[A Former User]

@Pablo-J-Rogina thanks for the warning
@mrjj take a look here i think you faced this type of problems
https://forum.qt.io/topic/71310/reading-barcode-from-barcode-scanner

[mrjj]

@davidlabib

Yes, that very normal issues when using a
scanner in HID mode so it acts like a keyboard.

I usually put a button next to input that says scan and it popup dialog
to do the scanning in.

There is no easy solution to what you try. as unless NOTHING else can have focus. ( you can disable focus for buttons) then user might switch to other edit fields.

Often scanner input is terminated with \n\r or similar- check the documentation
for the scanner.

[Pablo J. Rogina]

@davidlabib I did some grocery shopping yesterday, and looking at the point of sale software the clerk used when I checked out, and also thinking about the shopping cart and checkout process in websites, I wonder why do you need this "always on" scanning phase?

I mean, maybe you're overcomplicating your requirements. Do you really have such use case from an actual user/customer of your application?

While checking out most of the software overthere that I remember have some steps/phases:

1. Initial data (optional)
2. 1-N items scanning (using barcode reader!!) so focus is there for just one widget (a list where scanned items are added, or a line edit where you click a "Add" button, whatever)
3. When you are ready (by self-checkout or a clerk helping you) a "Proceeed to checkout" button move to next phase, i.e. Delivery information or just Payment (at this point if credit card is read, again focus is only for reading the credit card data)
4. "Finish" button to print receipt and move into next customer...

Is your use case completely different from this scenario? if so, why!?

[A Former User]

the only payment method is cash only (for now), so we can skip 3

It's not very require to make focus when the barcode input something but i thought that it will be a good extra feature in the application

[mrjj]

@davidlabib
Hi
The complication of trying to guess if its user typing or scanner input
can be complicated. While often a scan is terminated with same
symbols, you first know later if scan or keypress and hence
makes it complicated to handle.

So its actually complicated to make work flawless and hence a
straight way of saying for user. "I want to scan" is often preferred.
As it avoid confusing and guessing.

[raven-worx]

@davidlabib
just a note:
Some barcode scanners have different modes. One mode is "keyboard" mode (like you are using it now) and another can be via the serial interface. The later would let you use QtSerialPort module to receive the scanned code in plain text.
Those modes can be switched by scanning a special barcode. Take a look at the scanners manual.

[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.