Reading data from serial port

[ndevriendt]

Hello,

I've a barcode scanner where I can communicate in a two way direction.

I'm listening on a serial port to know if an user have scanned a barcode. When data is entered in the serial port by scanning a code, I send a message back to the serial port that will be displayed at the barcode scanner.

My problem is that the event DataReceived is triggerd when I sent data to the serial port (by using a write command) and I get at the command readline() again the data from de barcode that the user has scanned.

Is there a way to clear everything in de serial port ?
I have already tried to use DiscardInBuffer but this is not helping.

See here some code:
_sp = new SerialPort(port);
_sp.DataReceived += new SerialDataReceivedEventHandler(BarCodeScanner_DataReceived);
_sp.Open();

void BarCodeScanner_DataReceived(object sender, SerialDataReceivedEventArgs e)
{
barCode = _sp.ReadLine();
_sp.DiscardInBuffer();
// do some actions with the barcode
....
// Send a message
if (!(_sp.IsOpen)) _sp.Open();
_sp.Write(myMessage);
// After this write I comming back in this method and
// at ReadLine I'm getting back the barcode that the
// user has read. I'm looping...
}


I hope you can understand my problem.

Thans for your time and answer.

Devriendt Nico

 

[phinoppix]

I've never worked with the SerialPort component before, but just a suggestion, try using the WriteLine() instead. Somehow the datapacket must be terminated by one or more series of bytes when reading/writing from/to the port. I am only assuming that since you used ReadLine to read the data, then the data mustbe CRLF terminated.

Just my 2cents

 

[ndevriendt]

Hello,

Thanks for your answer but this is giving the same result as with the write command

Nico

 

[PatrickIRL]

Do you need to keep the port open all the time? If not then close the port when you finish writing to the scanner, (you're doing a check anyway) and clear the barcode variable too ...

Patrick

 

[ndevriendt]

Hello Patrick

Thanks for your answer.
My port need to be opened all the time.

I've done a close after the write like you said and then reopend my com port and this seems to work.

Many Thanks.

Devriendt Nico