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RS232 Connection

The RS232 standard interface (also known as EIA RS-232) is one of the commonly used serial communication interface standards, widely applied in data transmission between various devices. Its stability and reliability make it a preferred communication method for many devices. The protocol uses signal voltage levels different from standard 5V to transmit wire data, which can minimize signal interference to the greatest extent. In the 3D printer system, compared with CAN, RS232 has higher data transmission speed, better stability, simpler configuration, and better compatibility with the host computer.

Tool Board Uses RS232 to Connect to the Main Board​

  • Please note that the power line of the tool board is not connected to the RS232 signal line but to the 12V-24V power line.

  • No recompilation of the firmware is required for the D8 main board.

Search for RS232 ID​

Precautions Before Searching for Devices​

  • Before searching for the RS232 ID, please first connect to SSH
  • Please note that you need to ensure that you are logging in via SSH using the network, not via a serial port
  • Please ensure that UTOR is properly connected and that the data cable connecting to the host computer has data transfer capabilities
  • If using G2T, confirm whether the system supports UART connection

Searching for Devices​

  • Now that you have successfully logged into the host machine, you can enter lsusb to search for devices. This will result in one of the following scenarios:
    • If entering lsusb prompts that the ls command cannot be found, you can enter the following command to install the command: 
      sudo apt-get install usbutils
    • If entering lsusb results in no response, this indicates a system issue. You will need to change the system or use a confirmed working system.
    • If you see the information shown in the image below, please note that this is just a reference. You only need to determine the characters after the ID.
  • 1a86:7523 belongs to the device you need to use. The subsequent prompts do not need to be concerned with because system issues may cause it to display incompletely or not at all.
  • If none of these apply, please check if the data cable is properly connected and if the firmware has been correctly flashed.
Note

You can only use the commands below to search for the RS232 ID when you have 1a86:7523.

Searching for RS232 ID​

ls /dev/serial/by-path/*
  • If entering ls /dev/serial/by-path/* does not produce any IDs, but lsusb shows devices, consider replacing the host machine or the host machine's system.
  • Please note that using UTOR will output three IDs, and if you have used another UTOR system before, it may record them, leading to multiple IDs appearing during the search.
  • Ensure that the ID ends with -port0, otherwise it cannot be used.
Note

Please make sure that the tool board and UTOR are grounded!!! Otherwise, you will not be able to connect to the tool board!!!

Enter the RS232 ID into the Configuration​

  • Open the printer web interface and find the printer.cfg configuration under the configuration option in the left sidebar. For fluidd, it is {...}; for mainsail, it is machine.

  • Copy the blue ID and paste it into the [mcu] section of the printer.cfg configuration file under serial:. After saving and restarting, you should be able to connect to the mainboard. If Klipper prompts ADC out of range, this is normal. Connect the hotbed and thermistor properly, configure the thermistor pins and output pins for the nozzle and hotbed, then save and restart.

Note
  • The RS232 ID needs to be configured with baud: and restart_method:command.
  • Below is a reference configuration:
[mcu SHT36]
serial: /dev/serial/by-path/platform-1c1c000.usb-usb-0:1.2:1.0-port0
baud: 250000
restart_method:command
dangerous

Note: All IDs mentioned in the document are examples. Each motherboard’s ID is unique, so please modify and fill in according to the actual ID obtained.

dangerous

Please note that the IDs below cannot be used!!!

serial: /dev/serial/by-id/usb-1a86_USB_Serial-if00-port0