Stepcompress / invalide sequence error on specific model

General Discussion
1

Basic Information:

Printer Model: Kobra Go
MCU / Printerboard: Stock Kobra Go
klippy.log

klippy (3).log (1.5 MB)

gcodes-2024127-13542.zip (3.7 MB)

I have a problem I cannot get hold of, as I lack information on how to further debug this.
I’m printing a fan shroud model, and that specific model always emergency halts the printer in roughly the same spot.

I attached the gcode file and klippy.log.

The error I get is like this (just en excerpt of the log):

Receive: 96 1791996.826356 1791996.818707 14: seq: 12, analog_in_state oid=19 next_clock=3553096064 value=1588
Receive: 97 1791997.056428 1791996.818707 15: seq: 12, analog_in_state oid=12 next_clock=3591736064 value=25704
Receive: 98 1791997.126487 1791996.818707 14: seq: 12, analog_in_state oid=19 next_clock=3603496064 value=1587
Receive: 99 1791997.280476 1791997.277945 12: seq: 13, shutdown clock=3580171006 static_string_id=Command request
Exiting SD card print (position 658946)
Stats 1791998.3: gcodein=0  mcu: mcu_awake=0.004 mcu_task_avg=0.000020 mcu_task_stddev=0.000017 bytes_write=4421064 bytes_read=652729 bytes_retransmit=331 bytes_invalid=523 send_seq=76996 receive_seq=76996 retransmit_seq=74029 srtt=0.003 rttvar=0.000 rto=0.025 ready_bytes=11 upcoming_bytes=0 freq=167995743  heater_bed: target=70 temp=69.6 pwm=0.420 raspberry_pi: temp=37.5 sysload=0.07 cputime=92.537 memavail=7506820 print_time=2350.123 buffer_time=1.378 print_stall=0 extruder: target=240 temp=231.6 pwm=1.000
b'stepcompress o=2 i=0 c=6 a=0: Invalid sequence'
Exception in flush_handler
Traceback (most recent call last):
  File "/home/siebert/klipper/klippy/toolhead.py", line 427, in _flush_handler
    self._flush_lookahead()
  File "/home/siebert/klipper/klippy/toolhead.py", line 357, in _flush_lookahead
    self.lookahead.flush()
  File "/home/siebert/klipper/klippy/toolhead.py", line 176, in flush
    self.toolhead._process_moves(queue[:flush_count])
  File "/home/siebert/klipper/klippy/toolhead.py", line 354, in _process_moves
    self._advance_move_time(next_move_time)
  File "/home/siebert/klipper/klippy/toolhead.py", line 312, in _advance_move_time
    self._advance_flush_time(flush_time)
  File "/home/siebert/klipper/klippy/toolhead.py", line 303, in _advance_flush_time
    m.flush_moves(flush_time, clear_history_time)
  File "/home/siebert/klipper/klippy/mcu.py", line 938, in flush_moves
    raise error("Internal error in MCU '%s' stepcompress"
mcu.error: Internal error in MCU 'mcu' stepcompress
Stats 1791999.3: gcodein=0  mcu: mcu_awake=0.004 mcu_task_avg=0.000020 mcu_task_stddev=0.000017 bytes_write=4421102 bytes_read=652870 bytes_retransmit=331 bytes_invalid=523 send_seq=76999 receive_seq=76999 retransmit_seq=74029 srtt=0.003 rttvar=0.000 rto=0.025 ready_bytes=0 upcoming_bytes=0 freq=167995740  heater_bed: target=70 temp=69.6 pwm=0.524 raspberry_pi: temp=37.5 sysload=0.07 cputime=92.565 memavail=7507024 print_time=2350.389 buffer_time=0.644 print_stall=0 extruder: target=240 temp=231.6 pwm=1.000
Stats 1792000.3: gcodein=0  mcu: mcu_awake=0.002 mcu_task_avg=0.000015 mcu_task_stddev=0.000015 bytes_write=4421156 bytes_read=653024 bytes_retransmit=331 bytes_invalid=523 send_seq=77003 receive_seq=77003 retransmit_seq=74029 srtt=0.003 rttvar=0.000 rto=0.025 ready_bytes=0 upcoming_bytes=0 freq=167995743  heater_bed: target=70 temp=69.6 pwm=0.543 raspberry_pi: temp=37.0 sysload=0.07 cputime=92.588 memavail=7507024 print_time=2350.389 buffer_time=0.000 print_stall=0 extruder: target=240 temp=231.3 pwm=1.000

Other models print fine, so it might be related to that specific gcode file. Because of this, I’d also rule out communication issues, or would anyone disagree here?

How do I find out which GCODE line is the culprit (if any)?

Which steps could I undertake to understand the problem better and fix it?

Thanks for all the time being put into this great project!

2

STUPID ME

Seems I did not scroll up enough in the log file!

Heater extruder not heating at expected rate
Transition to shutdown state: Heater extruder not heating at expected rate

That’s very stupid of me.

Now I know what’s the fault: Too much cooling! I noticed that this part was some “bridging” fill, and the dual 5015 fans were pretty noisy just before the error. Okay.

Klipper’s not at fault. User error as always!

Again, sorry for raising this here, typical rubber duck situation.

1 Like
3

Are you using a sock on your heating block?
This is quite mandatory for strong part cooling and helps overall as well.

4

Yes I do. But the sock does not seem to help when those 2 blowers blow at 80%.

See attached temperature graph, where I tested this by setting extruder temp to 240C, then switched fans to 80%. This means that those fans are blowing away 40W of heat (wow):

image
image477×838 24.8 KB

If I let this run, klippy will eventuall panic and stop.

5

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