if checksum == NL or CR, false NOCHECKSUM generated?

[i-make-robots]

get_serial_commands() reads each line off the serial buffer until it hits a \r (13) or a \n (10) character.
commands follow the format

N[line number] [gocde];*[single byte checksum][CR and/or NL]

if the checksum of the line is equal to 10 or 13, the line would be truncated prematurely and a NOCHECKSUM error would be generated. If the PC software sends the exact same line again, an infinite loop would result.

A possible fix is to treat * as an escape character for the \n or \r check.

[Blue-Marlin]

The assumption the checksum is a single byte is wrong - it's the ASCII representation of a single byte.

[i-make-robots]

Ah. Ok then. Sorry!

[Blue-Marlin]

I admit this is a bit hidden

        if (apos) {
          byte checksum = 0, count = 0;
          while (command[count] != '*') checksum ^= command[count++];

          if (strtol(apos + 1, NULL, 10) != checksum) { //!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
            gcode_line_error(PSTR(MSG_ERR_CHECKSUM_MISMATCH));
            return;
          }
          // if no errors, continue parsing
        }

And somewhere is a misleading comment.

    /**
     * '#' stops reading from SD to the buffer prematurely, so procedural
     * macro calls are possible. If it occurs, stop_buffering is triggered
     * and the buffer is run dry; this character _can_ occur in serial com
     * due to checksums, however, no checksums are used in SD printing.
     */

That's wrong. '#' can't appear in the checksum.

Repetie Host:

02:48:02.791 : N39909 M105*45
                           ^^

[spilz87]

hello

can someone explain to me what is wrong when i try to send it after a M28 command
N1 ;TIME:10052*125
I receive :
Error:No Checksum with line number, Last Line: 0 Resend: 1 ok
I don't understand, there is the line number N1 ther is the '*' and the checksum

why it seems to don't find the checksum ??

[ellensp]

A) This is a closed bug report not a support forum.
B) everything after the ; character is a comment. and is dropped. Should not be sent to controller.

[spilz87]

Thank for your very quick reply

A) I know it’s not a support forum but there is no information in documentation about this function. As I worked 2 days to find why it doesn’t work, I could think there is an issue and open a new one. Before doing that I prefer asking somewhere people maybe know if it’s or not an issue.

B) it’s not obvious : the documentation explain M28 command is to send a file and the example is a .txt file. So the transfer shouldn’t care about what is in the file. You can want to send a config file or to keep comments in gcode file to use them later. I don’t really understand this choice.

Anyway thanks a lot, I will not find it alone

[AnHardt]

I'd start with a search for the problem by reverting #16840.

[thinkyhead]

@spilz87 — Here are the resources you should use instead of hijacking our issue queue:

• MarlinFW.org Marlin Documentation
• RepRap.org Marlin Forum
• Tom's 3D Forums
• Facebook Group "Marlin Firmware"
• Facebook Group "Marlin Firmware for 3D Printers"
• Marlin Configuration on YouTube
• Marlin Discord server. Join link: https://discord.gg/n5NJ59y

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[github-actions]

This issue has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.

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This issue has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.