Files
bambuddy/backend
maziggy 5be18ff57a fix(queue): print a plate whose filaments are all on the external spool (issue #3087)
The reporter's P1S heated up, sat at Heatbed preheating for ten and a half
minutes, then paused with 07FF_8012, "Failed to get AMS mapping table".
Resuming only reheated it. Prints that fed from the AMS were fine.

The plate was one filament of a seven-filament MakerWorld project, mapped by
hand to the external spool. slice_info.config numbers filaments across the
whole project, so the mapping for that plate is [-1,-1,-1,-1,-1,-1,254]: six
placeholders and the spool holder. The command builder decides whether a print
needs the AMS by asking whether the mapping is entirely external, and six -1s
answer no. So the print went out as use_ams=true carrying a flat mapping of
nothing but -1 -- 254 is deliberately never sent raw, the firmware reads it as
AMS tray 0 -- which is exactly the mapping table the firmware then could not
find.

The builder cannot fix this itself. Down there a -1 is either padding for a
filament this plate does not print, which is BambuStudio's own convention, or a
slot that never resolved to a tray, and sending the second one to the spool
holder is what #2589 exists to prevent. They are the same byte.

The scheduler knows. extract_filament_requirements drops every filament with
used_g <= 0, so it names precisely the slots the plate prints. When all of those
are an explicit 254/255, dispatch now sends use_ams=false and the print runs.
When one of them resolved to nothing, the flag is left alone and the firmware
rejects the print as it does today -- deliberately, because that is the case
where guessing would print a filament in the wrong material without saying so.

Single-nozzle only, mirroring the reconcile in the command builder: on a
two-extruder printer use_ams selects which nozzle to feed rather than whether to
use the AMS, so an H2D with a spool on each side must keep the flag it was
given. Judged generously from the model name and from live telemetry -- a second
nozzle reporting a diameter, an extruder map, or more than one external feed --
because a wrong yes only preserves existing behaviour while a wrong no would
reroute the print. H2S stays single-nozzle (#1386).

Nothing in the command builder changed. Its own reconcile keeps the exact
semantics #2589, #2595 and #797 gave it, and now usually agrees with a decision
that was already made one layer up. Where the file has no parseable filament
list the mapping is left exactly as before, the same evidence-only convention
as #2771, and the parse itself sits behind a check for anything external at all
so an AMS-only print never opens the file.

Covered end to end at the dispatcher, including the reporter's seven-filament
shape, a plate mixing the spool holder with an AMS tray, a consumed slot that
never resolved, both external feeds on a dual-nozzle machine, and a 3MF with no
filament list at all.
2026-09-18 17:55:06 +02:00
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