On comm timeout during resend request handling M105 will be triggered with wrong line number

[foosel]

Problem

Communication timeouts during resends trigger the M105 "revival mechanism", without honoring the resend's line number and instead using the current line number in the comm layer (which is too high). This leads to more "Resend" cascades and jumbling of line numbers.

How to reproduce

• Have a file with extremely long moves so that the firmware's planner buffer fills to the brim and comm timeouts occur (wrongly...)
• Provoke resend request in such a slow part of the file (e.g. via the virtual printer)

Observed behaviour

Send: N62 G1 X-70.472 Y-63.632 Z0.25 F535.8 E2.6067*71
Recv: ok T:255.2 /255.0 B:148.0 /148.0 T0:255.2 /255.0 @:7.29 B@:147.82

// ok for N59

Send: N63 G1 X-63.632 Y-70.472 Z0.25 F535.8 E0.1527*66
Recv: ok

// ok for N60

Send: N64 G1 X-61.753 Y-68.689 Z0.25 F535.8 E0.0409*66
Recv: ok

// ok for N61

Send: N65 G1 E-1.25 F1800.0*58
Recv: ok

// ok for N62

Send: N66 M103*17
Recv: Error:checksum mismatch, Last Line: 62
Recv: Resend: 63
Send: N63 G1 X-63.632 Y-70.472 Z0.25 F535.8 E0.1527*66
Recv: ok

// ok belonging to Resend

Recv: ok

// ok for N63

Send: N64 G1 X-61.753 Y-68.689 Z0.25 F535.8 E0.0409*66
Recv: ok
Send: N65 G1 E-1.25 F1800.0*58
Communication timeout during printing, forcing a line
Send: N67 M105*22

// wrong line number

Expected behaviour / Solution

Tricky to answer, but probably resending the same line that ran into a timeout makes more sense than trying to keep track of correct line numbers if M105 are sent in between active resend requests with increasing numbers.

So this should be the goal:

Send: N62 G1 X-70.472 Y-63.632 Z0.25 F535.8 E2.6067*71
Recv: ok T:255.2 /255.0 B:148.0 /148.0 T0:255.2 /255.0 @:7.29 B@:147.82

// ok for N59

Send: N63 G1 X-63.632 Y-70.472 Z0.25 F535.8 E0.1527*66
Recv: ok

// ok for N60

Send: N64 G1 X-61.753 Y-68.689 Z0.25 F535.8 E0.0409*66
Recv: ok

// ok for N61

Send: N65 G1 E-1.25 F1800.0*58
Recv: ok

// ok for N62

Send: N66 M103*17
Recv: Error:checksum mismatch, Last Line: 62
Recv: Resend: 63
Send: N63 G1 X-63.632 Y-70.472 Z0.25 F535.8 E0.1527*66
Recv: ok

// ok belonging to Resend

Recv: ok

// ok for N63

Send: N64 G1 X-61.753 Y-68.689 Z0.25 F535.8 E0.0409*66
Recv: ok
Send: N65 G1 E-1.25 F1800.0*58
Communication timeout during printing, forcing a line
Send: N65 G1 E-1.25 F1800.0*58
Recv: ok

// ok for N65

Recv: Error:line is not last line + 1, Last Line: 65
Recv: Resend: 66

// expected, since it did receive N65 twice

Send: N66 M103*17
Recv: ok

// ok belonging to Resend

Recv: ok

// ok for N66

[foosel]

Solved through commit c900949

[foosel]

Merged to master