Model: K1 / K1 Max / K2 Plus (please adjust as needed)

Serial Numbers:

• CFS #1: [insert]

• CFS #2: [insert]

• Printer: [insert]

Issue Summary:

I am using two Creality CFS units with my printer. Both units function flawlessly when connected individually to the printer. However, when both are connected via the standard 6-pin RS-485 COMM daisy-chain, the second CFS (assigned as “No. 2”) frequently fails with feed-related errors, including:

* FR2836 – Feed issue

* FR2849 – Cannot retract filament

* FS2831 – Communication issue

When trying to pull filament from CFS #2, the printer makes a buzzing sound at the cutter/multiplexer, and the filament never reaches the break sensor. This does not occur when CFS #1 is used.

Troubleshooting Steps Performed:

* ✅ Swapped the order of the CFS hubs (made CFS #2 into the primary device)→ CFS #2 works fine when first in the chain; the issue follows the second position, not the device

* ✅ Replaced the RS-485 COMM jumper cable with a new, shielded version

* ✅ Confirmed both CFS units are updated to the latest firmware (≥ v1.1.5)

* ✅ Recalibrated the cutter and printer

* ✅ Verified PTFE paths are clear, correctly inserted, and working

* ✅ Proper termination: only the last hub in the chain has terminator switch ON

Conclusion:

All tests indicate that the issue arises only when a second CFS unit is in the RS-485 chain. Based on test results and behavior, I suspect:

* A faulty pass-through port (COMM OUT) on CFS #1, or

* A firmware-level communication timing issue with a multi-hub setup

Requested Action:

Please advise whether a replacement COMM port module or mainboard for CFS #1 can be provided, or if there is a known firmware-level fix. I can provide video, logs, or additional diagnostics if needed.

I appreciate your support.

Best regards,

Waqar

Intermittent Feed Errors from CFS #2 When Both Units Are Connected – Suspected RS-485 Communication