---
title: "Node Web UI"
space: "Node UIO"
url: "https://docs.modbee.org/node-uio/web-ui"
updated: "2026-10-25"
---

# ModBee Node Web UI

A small web interface for the [ModBee Node UIO](https://github.com/mod-bee/modbee-node-uio/tree/main/node-uio): a live view of the
board's digital and analog I/O and its network, and an editor for the analog
calibration.

It reads and writes the board through `NodeUioAPI`, the same surface the
OpenPLC blocks use, so the page cannot disagree with the rest of the firmware
about what a value means.

## What it does

- Serves a page from LittleFS at `/` (`data/www/`).
- Pushes the board state to every browser on a WebSocket at `/ws`, once a
  second: digital inputs and outputs, analog inputs in V or mA, analog output
  counts, calibration, and the network mode, SSID and IP address.
- Accepts a calibration from the page and saves it to NVS.

It does **not** bring a network up. Something else owns the radio, such as
`uio().connect()` in a sketch or the NETWORK block under OpenPLC, and this
library binds a port on whatever network is there. `begin()` returns false, and
`update()` keeps trying, until there is one.

## Using it

```cpp
#include <NodeUioAPI.h>
#include <NodeWebUI.h>

NodeWebUI webui(80);

void setup() {
  uio().begin();
  uio().connect("your-network", "your-password");
}

void loop() {
  uio().update();
  webui.update();   // starts serving once the network is up
}
```

`examples/NodeWebUIBasic` is the above as a sketch. `running()` says whether
the server has started and `clients()` how many browsers are on the live feed.

## The page

The page lives in a LittleFS filesystem image, not in the firmware, so it is
uploaded separately. With PlatformIO, from this directory:

```bash
pio run -e lolin_s3_mini -t upload      # firmware
pio run -e lolin_s3_mini -t uploadfs    # the page, from data/
```

Without the filesystem image the WebSocket still works and the page requests
return 404.

## Security

The page and the WebSocket have no authentication. Anyone who can reach the
board on the network can see its I/O and change its analog calibration. Use it
on a trusted network only.

## Dependencies

- [ModBeeNodeUIO](https://github.com/mod-bee/modbee-node-uio/tree/main/node-uio), the board library in this repository
- [ArduinoJson](https://github.com/bblanchon/ArduinoJson) 7
- [AsyncTCP](https://github.com/ESP32Async/AsyncTCP)
- [ESPAsyncWebServer](https://github.com/ESP32Async/ESPAsyncWebServer)

## Licence

AGPL-3.0, see [LICENSE](https://github.com/mod-bee/modbee-node-uio/blob/main/node-webUI/LICENSE).