2.4 Test Wi-Fi and SD Card

Check List · Step 4 of 12 · Connect to Wi-Fi, open FluidNC WebUI, and verify TF / microSD card detection

ℹ️

Objective: This step verifies that the controller can start the default FluidNC Wi-Fi access point, that the WebUI can be opened in a browser, and that the TF / microSD card can be detected by the system if installed.

⚠️

Before starting: Make sure Step 2.2 has been completed and the board is powered on. If you reinstalled firmware in Step 2.3, make sure both config.yaml and index.html.gz have been uploaded before testing the WebUI.

1

Wi-Fi Connection

Open the Wi-Fi network list on your computer.
Find and connect to the FluidNC access point.
Wi-Fi SSID: fluidnc
Password: 12345678

💡 The Wi-Fi network is created by the controller board itself. Your computer does not need to be connected to your home router for this test.

2

Web Interface Access

Open the Google Chrome browser.
Enter the address: 192.168.0.1
Wait for the FluidNC WebUI page to load.
Confirm that the WebUI interface can be opened normally.

Reference image: connect to the FluidNC WebUI and check the TF / microSD card file area.

Item	Default Value
Wi-Fi SSID	fluidnc
Password	12345678
WebUI Address	192.168.0.1
Recommended Browser	Google Chrome

3

Console Messages You May See

When the WebUI console first loads, the controller prints a few startup messages. The two below are normal on the V5.88 Ultra and do not mean there is a fault.

No OLED installed: a red OLED missing warning is shown in the console. This only means no OLED display was detected — the controller still works normally and the warning can be safely ignored.
USB UNPLUGGED message: when the board is connected through the CP2102 USB port, FluidNC may repeatedly print USB UNPLUGGED in the console (the ESP32-S3 native USB channel is unused). To stop these messages, send the command below once.

$USBCDC/Enable=OFF type in WebUI console

💡 This setting is stored in the controller (NVS) and stays active after power cycles, so the USB UNPLUGGED messages will not appear again.

4

TF Card Content Display Verification

If a TF / microSD card is installed, open the file or SD card section in the WebUI.
Confirm that the card is detected by the system (optional).
If the card contains files, confirm that the file list can be displayed.
If no TF / microSD card is installed, this part can be skipped.

💡 The TF / microSD card test is optional. It is mainly used to confirm that the SD card slot and WebUI file listing are working correctly.

✅

Normal behavior: If the WebUI opens successfully and the controller remains connected, the Wi-Fi function is working. If a TF / microSD card is inserted and the file list can be displayed, the card detection is also working.

🔧 Quick Troubleshooting

If you cannot find fluidnc, restart the board and wait about 10 seconds.
If 192.168.0.1 does not open, confirm that your computer is connected to the fluidnc Wi-Fi network.
If the WebUI page is missing or blank after reinstalling firmware, upload index.html.gz again.
If the USB UNPLUGGED message keeps repeating, re-send $USBCDC/Enable=OFF in the console and confirm it is accepted (ok).
If the TF / microSD card is not detected, power off the board, reinsert the card, then power on again.
Use a FAT32-formatted TF / microSD card for better compatibility.

✓

Expected Results

The computer can connect to the Wi-Fi SSID fluidnc using password 12345678.
The FluidNC WebUI can be opened from 192.168.0.1.
If OLED installed: The display shows normal operation with no errors.
If OLED not installed: A red OLED missing warning is shown in the console, but the controller remains fully functional.
USB console: After sending $USBCDC/Enable=OFF, the USB UNPLUGGED messages no longer appear.
If TF / microSD card installed: The system detects the card and can display its contents in WebUI.

← 2.3 Upload Firmware and Config Files Step 4 of 12 2.5 Test Probe and Endstop Inputs →