Bays, Lanes and Hot-Swap¶

An AMS can be plugged in or pulled out while Klipper runs. Its lanes, its T# commands and its place in the web interface and the dryer panel appear and go away live, with no restart.

Why bays¶

Klipper builds its lanes when it reads the config, and there is no way to add a lane to a running Klipper. So at startup the BridgeBox chain builds a pool of bays ahead of time:

AMS bays, four lanes each, up to pool_ams (at most 4);
AMS HT bays, one lane each, up to pool_ht.

An empty bay is hidden: its lanes have no T# and AFC's PREP, the web interface and the dryer panel skip it. When a unit comes online it claims a bay of its kind, and the bay's lanes and T# come to life. When it is unplugged and auto_drop is on, it releases the bay again.

The first claim¶

A new unit comes online and claims a free bay of its kind, lowest lanes first. Its lanes appear at once.

Once it has stayed online for 15 seconds (enroll_grace), the bay is saved for it. The console says:

AFC_BridgeBox chain1: saved <UID> on Bambu_AMS_1 (lane0-lane3); it comes back there after a restart.

From then on the bay is reserved for that unit. After a restart, or when it is plugged back in, it returns to the same lanes and T#, with its spools and settings.

A New AMS popup in Mainsail or Fluidd tells you which bay the unit took and offers the other free bays of the same kind, in case you want it elsewhere. Dismiss keeps it where it is.

Lane layout¶

Lanes are laid out in fixed bands, so a unit's lanes never move when other units come and go:

AMS bay N takes four lanes starting at lane_base + 4 × (N - 1).
The AMS HT bays follow the AMS band, one lane each.

With lane_base: 0 and the default pools:

Bay	Lanes
`Bambu_AMS_1`	lane0 - lane3
`Bambu_AMS_2`	lane4 - lane7
`Bambu_AMS_3`	lane8 - lane11
`Bambu_AMS_4`	lane12 - lane15
`Bambu_AMS_HT_1`	lane16
... up to `Bambu_AMS_HT_8`	lane23

The HT band starts in the same place whether one AMS is plugged in or four.

`lane_base`¶

With the default lane_base: 0, the chain picks the base at the first start: one past the highest lane any other unit uses, or 0 when the BridgeBox is the only unit. Beside a BoxTurtle on lane0 - lane3 that gives 4, so Bambu_AMS_1 is lane4 - lane7. The base is then saved, so lanes added to other units later do not move the Bambu ones.

Warning

Set lane_base before the first start if you want the Bambu lanes somewhere specific. Changing it later moves every Bambu lane, and those lanes lose their saved details.

`T#` commands¶

T# does not follow lane numbers. A claimed lane takes the next unused T#, the same way AFC numbers any lane. On its own, the first AMS gets T0 - T3; beside a unit already on T0 - T3, it gets T4 - T7.

A unit with a saved bay keeps its T# while it is unplugged and across restarts.
SET_MAP and AFC's other mapping commands change a Bambu lane's T# like any other lane, and the change is saved.
When a unit is retired with AFC_BRIDGEBOX_FORGET, the next start packs the other Bambu T# down into the freed ones. Lane numbers and names stay.

Unplugging a unit¶

auto_drop: Trueauto_drop: False

Once a unit has been offline for release_grace (10 seconds), its lanes and T# drop live and an AMS removed popup appears. Its bay stays reserved, so plugging it back in brings it back on the same lanes.

A unit is never dropped during a print, or while one of its lanes is loaded to the toolhead.

The unit's lanes stay until the next restart. Plug it back in and it carries on where it was.

Managing bays¶

Command	What it does
`AFC_BRIDGEBOX_BAYS`	Opens the bay manager: every bay, who is on it and an Unassign button for each.
`AFC_BRIDGEBOX_ASSIGN UID=<uid> NAME=<bay>`	Moves a unit to another bay and saves it there. Without `NAME` it opens a bay picker.
`AFC_BRIDGEBOX_UNASSIGN UID=<uid>`	Frees a unit's bay but keeps what the chain learned about the unit.
`AFC_BRIDGEBOX_FORGET UID=<uid>`	Retires a unit for good and frees its bay. Without arguments it opens a picker.
`AFC_BRIDGEBOX_REPLACE UID=<new> OLD=<old>`	Puts a new unit on an offline unit's bay.

Use a unit's UID or its bay name. AFC_BAMBU_UIDS lists the UIDs on the bus. On a printer with more than one BridgeBox, add CHAIN=<name> for any chain but the first, such as AFC_BRIDGEBOX_BAYS CHAIN=chain2 (see More than one BridgeBox).

A lane loaded to the toolhead

FORGET, UNASSIGN, ASSIGN and REPLACE refuse a bay with a lane loaded to the toolhead. Unload the lane first. If the filament is already out, FORCE=1 clears AFC's record of it.

No free bay¶

When every bay of a unit's kind is taken, the new unit waits. If one of the bays belongs to a unit that is offline, a No free bay popup offers to replace it. Replacing forgets the old unit and moves the new one onto its bay, lanes and T#.

Turning hot-swap off¶

pool_ams: 0 together with pool_ht: 0 turns live claiming off. The chain then only records the units it sees, and their lanes come up only through AFC_BRIDGEBOX_ASSIGN, again after every restart. Most setups should leave the pool on.

Next step: Spools, RFID and Spoolman