send binary file over serial port with QSerialDevice

[marcvanriet]

Hi,

if r is equal to the file size the program prints "Writed binary file."
The error is: the program sends all the bytes but if there is a XOFF the device doesn't read all the bytes.

Just to make sure I understand you right : you do get the message "Writed binary file.", right ? This may be significant because QSerialDevice doesn't send all data at once, but in chuncks of 512 or so bytes. It might be that the serial port driver returns false on a write() when an XOff has been received. Unlikely though.

I thought the QSerialDevice manage this XON/XOFF but I don't know if it works.

The operating system should take care of this. QSerialDevice doesn't need to do this.

It is very easy to implement the Xon/Xoff handshaking yourself :

// until all data sent :
//   send a chunck of data
//   if something is received from the printer :
//       if Xoff was received :
//             wait until Xon received

// until all data sent :
//   send a chunck of data
//   if something is received from the printer :
//       if Xoff was received :
//             wait until Xon received

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Best regards,
Marc

[squidge]

What is likely is that if you are sending data that is larger than the serial port buffers. What does QSerialDevice typically set the serial buffers to?

Also, try sending in smaller chunks, say 128 bytes or even 64 or 32 bytes (you can always increase the number if it starts to work) and possibly put in a small delay between each chunk, say 100ms or so.

[kuzulis]

Also, try sending in smaller chunks, say 128 bytes or even 64 or 32 bytes (you can always increase the number if it starts to work) and possibly put in a small delay between each chunk, say 100ms or so.

Yes, you can try to reduce the size of the pieces, as The default library sends data chunks of 512 bytes:

#define WRITE_CHUNKSIZE Q_INT64_C(512)

#define WRITE_CHUNKSIZE Q_INT64_C(512)

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[ilpaso]

Yes, you can try to reduce the size of the pieces, as The default library sends data chunks of 512 bytes:

#define WRITE_CHUNKSIZE Q_INT64_C(512)

#define WRITE_CHUNKSIZE Q_INT64_C(512)

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Tomorrow I'll try to implement the Xon/Xoff handshaking myself and find the right buffer.
Thank you

ilpaso

[ilpaso]

Hi all,
I implemented myself the flow control and the transfer works with a buffer size of 256bytes and 512bytes.
I tried to change the "WRITE_CHUNKSIZE" variable to 256bytes and send datas without my flow control. The transfer doesn't work.

[marcvanriet]

Great.

Maybe kuzulis could integrate it in QSerialDevice. Xon/Xoff handshaking in software instead of in the driver of the OS.

Regards,
Marc