Using a serial port monitor

A basic feature of FluidNC is the serial port interface. On most modules and controllers this will be interfaced via USB. The USB connection creates a serial port on your computer. This USB/Serial interface is part of the hardware and is not affected if you reboot the ESP32 and if the firmware crashes. Other interfaces, like WiFi or Bluetooth rely on the firmware and take time to reconnect each time the ESP32 restarts.

Therefore we use the serial port to display important information during the startup process. If you are having problems and want some help, we will most likely need to see the startup messages and interact with FluidNC via the serial port. Before requesting help, please try to have a serial port monitor connected and communicating with the controller.

Serial Port Parameters

The FluidNC serial port boots with the following settings. After booting it may switch to another speed.

• Baudrate: 115200
• N,8,1
• End of line: CR (carriage return)
• COM Port number: This depends on your system

Serial Port Monitor Programs

Below is a list of the simplest ones we know of. If you are experienced with other ones, you can use them.

• Arduino IDE
• PlatformIO
• Python miniterm
• fluidterm - A special version of miniterm

Startup Messages

Crash Messages (Backtrace)

If the firmware ever crashes it will dump a bunch of text to the serial port. This can tell the developers exactly where in the firmware the crash occurred. Please be ready to supply this data when requesting help.