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RS232 Firmware Connection Guide

Firmware Preparation​

  • Before entering RS232 mode, first use a Type-C cable to flash the toolboard with the pre-compiled RS232 firmware for the toolboard.

Wiring Steps​

Setting the DIP Switches​

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

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

Connecting Cables​

  1. Keep Power Off: The device must not be powered on during the entire wiring process.
  2. Prepare Cable: Prepare a XT30(2+2)-F four-core cable. The pin 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 UTOR Module RS232 Expansion Port
White/GreenOUT (Signal Output)IN pin of UTOR Module RS232 Expansion Port
  1. Complete Connection:
    • Insert the male connector of the cable into the corresponding interface on the toolboard.
    • Insert the female connector of the cable into the corresponding interface on the UTOR module.
    • Connect the UTOR module to the host computer (e.g., FLY Pi, Raspberry Pi, or PC) using a USB cable.

Check Common Ground​

  • Use a multimeter in continuity/resistance mode to measure the following two points:
    • GND on the toolboard
    • GND on the host computer
  • Ensure continuity between the two grounds (resistance close to 0Ω). If there is no continuity, communication cannot be established. Check that the wiring is complete and secure.

Search and Configure Toolboard RS232 ID​

🔴 Important Preparation​

Warning
  1. Firmware Requirement: The toolboard must be flashed with RS232 firmware. Otherwise, communication will not be possible.
  2. Mandatory Common Ground: ⚠️ You must ensure that the toolboard and the mainboard share the same GND (connecting them to the same 24V/12V power supply will achieve this).

📌 Hardware Notes​

  • Only D8, D8-Pro, C8P mainboards support a native RS232 interface.
  • Other mainboards need to be connected via a UTOR or G2T module (this tutorial uses UTOR as an example).

🔍 Steps to Search for RS232 ID​

Step 1: Access the Host Interface​

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

  1. Go to the left menu. Find and click printer.cfg:

    Fluidd
    Click the {…} icon

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    Mainsail
    Click the "Machine" menu

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Step 3: View the Device List​

  1. Click the DEVICES button in the upper right corner:
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Step 4: Refresh the 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 with ttyUSB. Copy its Path_by_hardware value:

    Fluidd
    Confirm that ttyUSB and Path_by_hardware exist

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    Mainsail
    Confirm that ttyUSB and Path_by_hardware exist

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Note for UTOR Users
  • When using a UTOR connection, there are usually two candidate IDs. Please try them one by one to determine the correct ID.
  • Click the arrow icon next to the ID to copy it.

⚙️ Configure the RS232 ID in the Firmware​

Configuration Notes
  • In the configuration below, toolboard refers to the toolboard name. Please replace it according to the 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 this with the actual ID you found>
baud: 250000
restart_method: command

Configuration Steps:​

  1. Enter the copied ID after the serial: parameter.
  2. Click SAVE & RESTART in the upper right corner to save and restart Klipper.
Important Warning
  • All IDs in the document are examples. Do not copy and use them directly.
  • Be sure to enter the hardware ID you actually obtained.
  • The following ID is an invalid example. Do not use it: 
    serial: /dev/serial/by-id/usb-1a86_USB_Serial-if00-port0

Important Note: Regarding RS232 ID​

Core Point​

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

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: "Please use this interface of yours to connect to the toolboard."
  • Regardless of whether the toolboard is connected, as long as the UTOR module is connected to the host computer, this ID will exist.

Simple Explanation​

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

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

Practical Tips​

  • Having UTOR allows you to find the ID, but only with the toolboard working properly can communication occur.
  • The ID usually changes because the UTOR has been plugged into a different USB port or the system has been restarted.
  • Ensure the toolboard is correctly connected and powered when configuring.
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