The Problem

If you have multiple CFS (Creality Filament System) boxes connected to your K1-series printer, you may have noticed that the boxes randomly swap positions (T1/T2) on each reboot. This causes your filament slot order to be inconsistent in Orca Slicer, Creality Print, and on the printer's display.

For example:

Sometimes your "Box A" is T1 and "Box B" is T2

After a reboot, "Box B" becomes T1 and "Box A" becomes T2

Your carefully organized filament colors are now in the wrong order

This is frustrating when you've set up specific filaments in specific slots and expect them to stay that way.

Root Cause

The CFS boxes communicate with the printer over an RS-485 serial bus. On startup, the printer's Klipper firmware broadcasts a request for all CFS boxes to identify themselves. The boxes respond with their unique hardware IDs, and Klipper assigns addresses (T1=0x01, T2=0x02, etc.) based on which box responds first.

This is a classic race condition - the response order depends on tiny timing differences in the RS-485 bus, power-on timing of each box, and other non-deterministic factors. The result is random address assignment on each boot.

Looking at the Klipper logs, you'll see messages like:

Error: mb_addr_table_uniids not exist

alloc method 2 addr 1

alloc method 2 addr 2

The "alloc method 2" indicates dynamic allocation (first-come-first-served), which is the source of the randomness.

The Solution

The auto_addr_wrapper.py module in Klipper supports a configuration parameter called mb_addr_table_uniids that lets you pre-define which unique hardware ID should be assigned to which address. When this is configured, Klipper uses "alloc method 1" (saved mapping) instead of "alloc method 2" (dynamic).

Step 1: Find Your CFS Box Unique IDs

First, you need to identify the unique hardware IDs for each of your CFS boxes. These are 12-byte identifiers burned into each box at the factory.

SSH into your printer and check the Klipper logs after a fresh boot:

ssh root@<your-printer-ip>

grep "print_addr_manager_table" /usr/data/printer_data/logs/klippy.log | tail -10

You'll see output like:

[INFO] ... print_addr_manager_table:480] 0x01, 0x24, 0x5C, 0x3B, 0x48, 0x24, 0x22, 0xB0, 0x02, 0x36, 0x35, 0x34, 0x34, 1, 1, 1, 0, mode:0

[INFO] ... print_addr_manager_table:480] 0x02, 0xB7, 0x6C, 0x30, 0x20, 0x10, 0x30, 0x33, 0x0E, 0x47, 0x34, 0x38, 0x37, 1, 1, 1, 0, mode:0

The format is: address, unique_id_byte1, unique_id_byte2, ..., unique_id_byte12, ...

To correlate unique IDs with serial numbers (printed on your CFS boxes), check:

grep "sn.*boxID\|boxID.*sn" /usr/data/creality/userdata/box/material_box_info.json

Or look in the logs for GET_VERSION_SN entries near the unique ID assignments.

Step 2: Edit box.cfg

Open the box configuration file:

nano /usr/data/printer_data/config/box.cfg

Find the [auto_addr] section (it may be empty) and add the mb_addr_table_uniids parameter:

[auto_addr]

mb_addr_table_uniids =

0x24, 0x5C, 0x3B, 0x48, 0x24, 0x22, 0xB0, 0x02, 0x36, 0x35, 0x34, 0x34

0xB7, 0x6C, 0x30, 0x20, 0x10, 0x30, 0x33, 0x0E, 0x47, 0x34, 0x38, 0x37

0x00

0x00

Important notes:

The first line becomes T1 (address 0x01)

The second line becomes T2 (address 0x02)

You must have exactly 4 entries (use 0x00 for unused slots)

Each unique ID is 12 bytes in hex format, comma-separated

Step 3: Power Cycle

A simple Klipper restart may not be enough - the CFS boxes need to re-initialize on the RS-485 bus. Fully power cycle the printer and all CFS boxes.

Step 4: Verify

After the system comes back up, verify the fix:

# Check that the address table matches your config

grep "print_addr_manager_table" /usr/data/printer_data/logs/klippy.log | tail -4

# Check the material_box_info.json has correct SN-to-boxID mapping

grep -E "boxID|sn" /usr/data/creality/userdata/box/material_box_info.json | head -8

You should also see in the logs:

addr table uniid get mb_addr_table_uniids

This confirms Klipper is reading your configuration.

Troubleshooting

Wrong order after fix

If the boxes are still in the wrong order after adding the config, you likely have the unique IDs swapped. Simply swap the first two lines in mb_addr_table_uniids and power cycle again.

"Error: no response" in logs

This usually happens right after a Klipper restart without power cycling the CFS boxes. The boxes need a full power cycle to re-initialize their RS-485 communication.

Config not being read

If you still see "Error: mb_addr_table_uniids not exist" and "alloc method 2", double-check:

The parameter name is spelled correctly

The indentation uses spaces (not tabs)

Each unique ID line is properly indented under the parameter

The file was saved correctly

Technical Details

The relevant code is in /usr/share/klipper/klippy/extras/auto_addr_wrapper.py:

get_addr_table_uniids() (line ~178): Reads the mb_addr_table_uniids config

addr_allocate() (line ~247): Uses "method 1" if saved IDs exist, "method 2" otherwise

The address table supports up to 4 CFS boxes

The unique ID is a hardware identifier separate from the serial number. The serial number (visible on the box and in the UI) is queried after address assignment via the GET_VERSION_SN command.

Fixing Random CFS Box Order on Creality K1/K1C/K1 Max