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RS232 Firmware Connection Guide

Firmware Preparation​

  • Before entering RS232 mode, please first flash the RS232 firmware (pre-compiled for the toolboard) onto the toolboard via a Type-C data cable.

Connection Steps​

Setting the DIP Switches​

  1. Power Off Safely: Ensure the toolboard is completely disconnected from the power source before operation.
  2. Locate DIP Switches: Flip the toolboard over. Find the DIP switch group on the back.
  3. Switch Mode: Set all DIP switches to the specified position for RS232 mode (see image below).
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Warning

  • If the DIP switch state is changed, the RS232 firmware must be re-flashed. Otherwise, communication will fail.
  • If the correct firmware was previously flashed and the DIP switches have not been changed, re-flashing is not necessary.

Connecting Cables​

  1. Keep Power Off: The device must remain powered off throughout the entire connection process.
  2. Required Cable: Prepare an XT30(2+2)-F 4-core cable. The core definitions are as follows:
Wire ColorSignalConnection Target
RedVCC (Power Positive)12V–24V Power Supply Positive
BlackGND (Power Negative)Power Supply Negative
YellowIN (Signal Input)OUT pin of the UTOR module's RS232 expansion port
White/GreenOUT (Signal Output)IN pin of the UTOR module's RS232 expansion port
  1. Complete Connection:
    • Insert the cable's male connector into the corresponding port on the toolboard.
    • Insert the cable's female connector into the corresponding port on the UTOR module.
    • Connect the UTOR module to the host computer (e.g., FLY-Pi, Raspberry Pi, or PC) using a USB cable.

Checking Common Ground​

  • Use a multimeter in buzzer/continuity or resistance mode to measure between the following two points:
    • GND on the toolboard
    • GND on the host computer
  • It is essential to ensure continuity between these grounds (resistance close to 0Ω). If there is no continuity, communication cannot be established. Please check if the wiring is complete and secure.

Searching and Configuring Toolboard RS232 ID​

🔴 Important Preparation​

Warning
  1. Firmware Requirement: The toolboard must be flashed with the RS232 firmware. Otherwise, communication is impossible.
  2. Mandatory Common Ground: ⚠️ You must ensure the GND of the toolboard is connected to the GND of the mainboard (sharing the same 24V/12V power supply achieves this).

📌 Hardware Notes​

  • Only D8, D8PRO, C8P mainboards support native RS232 interfaces.
  • Other mainboards require connection via a UTOR or G2T module (this tutorial uses UTOR as an example).

🔍 Steps to Search for RS232 ID​

Step 1: Access the Host Computer​

  1. Open a browser. Enter the host computer's IP address (e.g., 192.168.101.179).
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Step 2: Open the Configuration File​

  1. Navigate to the left-side menu. Find and click on printer.cfg:

Fluidd
Click the {…} icon.

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Mainsail
Click the "Machine" menu.

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Step 3: View Device List​

  1. Click the DEVICES button in the top-right corner:
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Step 4: Refresh Serial Devices​

  1. Click SERIAL and refresh the list:
Fluidd
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Mainsail
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Step 5: Copy the RS232 ID​

  1. Find the device containing ttyUSB. Copy its Path_by_hardware value:

Fluidd
Confirm the presence of ttyUSB and Path_by_hardware.

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Mainsail
Confirm the presence of ttyUSB and Path_by_hardware.

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Note for UTOR Users
  • When using UTOR, two candidate IDs usually appear. Try each one to determine the correct ID.
  • Click the arrow icon next to the ID to copy it.

⚙️ Configuring the RS232 ID into the Firmware​

Configuration Note
  • toolboard in the configuration below refers to the toolboard name. Replace it according to your actual situation.
  • The toolboard configuration should be [mcu toolboard]. The mainboard configuration is [mcu]. Do not confuse them.

Reference Configuration:​

Configuration Template
[mcu toolboard]
serial: <Replace here with the real ID you found>
baud: 250000
restart_method: command

Configuration Steps:​

  1. Paste the copied ID after the serial: parameter.
  2. Click the SAVE & RESTART button in the top-right corner to save and restart Klipper.
Important Warning
  • All IDs in this document are examples. It is strictly forbidden to copy and use them directly.
  • You must fill in the hardware ID you actually obtained.
  • The following IDs are invalid examples and must not be used: 
    serial: /dev/serial/by-id/usb-1a86_USB_Serial-if00-port0

Important Note: About the RS232 ID​

Core Point​

The RS232 ID you searched for is the ID of the UTOR module itself, not the toolboard's ID.

Key Understanding​

  • This ID represents the connection interface between the UTOR module and the host computer.
  • The host computer uses this ID to tell the UTOR module: "Please connect to the toolboard through this interface of yours."
  • Regardless of whether the toolboard is connected, as long as the UTOR module is connected to the host computer, this ID will exist.

Simply Put​

Host Computer → [UTOR Module (ID)] → Toolboard

You are configuring the address of the middle box (UTOR), not the address of the toolboard.

Practical Tips​

  • You can find the ID as long as UTOR is connected, but communication only works if the toolboard is properly connected and powered.
  • ID changes usually occur because the UTOR was moved to a different USB port or the system was rebooted.
  • Ensure the toolboard is correctly connected and powered when configuring.
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