Talk to industrial devices from a browser tab.
在浏览器里直接调设备。
_{Serial · WebSocket · MQTT · Modbus RTU · HART · custom protocols}

English · 中文 · Try it now → · Request a device

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AOMaster 4-20 mA / 0-10 V 6 waveforms

HART vendor-agnostic PV / SV / TV / QV

WebSocket JSON / HEX / Modbus + live chart

MQTT pub / sub · QoS retain · stats

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What it is

A static web app for debugging serial / WebSocket / MQTT devices from a browser. No installer, no backend, no database. Open the page, pick a device, connect, and you get raw frames, manual send, parsed values, and a real-time chart.

Open a tab. Plug in a device. Talk to it.

Use cases

• Bench-test a Modbus RTU board without firing up a 200 MB vendor tool
• Walk into a plant with a USB-to-485 dongle and a laptop, and you have a HART debugger
• Bring up a new MQTT/WebSocket-speaking device and watch traffic on a live curve
• Hand a colleague a URL instead of a setup.exe
• Build a quick UI for an in-house protocol with the Custom device page (no JS required)

Not what it's for: long-running data acquisition, plant monitoring, anything you'd actually call SCADA.

Built-in devices

Device	Transport	Default	Notes
AOMaster	Serial	115200 8N1	4-20 mA / 0-10 V signal source, 6 waveforms
Modbus RTU	Serial	9600 8N1	Read / write holding & input registers
HART	Serial	1200 8O1	Device search, universal commands, PV/SV/TV/QV
WebSocket	WebSocket	—	JSON / HEX / Modbus message debug
MQTT	MQTT over WS	—	Pub / sub, QoS, retain, message stats
Custom	any	—	Template + parser, no code

Switching device also switches the transport and its defaults.

Quick start

Serve the repo as static files:

python -m http.server 4173

Open http://localhost:4173 in Chrome or Edge. That's it — no install, no build.

To produce a deployable build:

npm install
npm run build
npm run preview

The build script is scripts/build.mjs (esbuild). Output goes to _site/.

Offline package

Use this when you want a self-contained copy on a laptop or a plant PC without cloning the repo.

Download

• Push to main: open Actions → Offline package, pick the latest run, download the artifact modusignal-offline-<version>.zip.
• Tagged release (v*): download modusignal-offline-<tag>.zip from Releases.

Run locally

Double-click start-modusignal.bat (Windows) or run start-modusignal.sh (macOS/Linux). It starts a local server and opens the browser.

Or manually:

python -m http.server 4173

Open http://localhost:4173 in Chrome or Edge. Web Serial needs localhost or HTTPS.

Build the zip yourself

npm install
npm run build:offline

Output: _release/modusignal-offline-<version>.zip (or .tar.gz if zip is not installed).

Browser support

Feature	Browsers
Serial (Web Serial API)	Chrome / Edge 89+, HTTPS or localhost
WebSocket	any modern browser
MQTT over WebSocket	any modern browser

Firefox and Safari don't ship Web Serial, so serial devices won't work there. Everything else works.

Architecture

index.html              app shell (topbar, sidebar, mount points)
pages/
  home.html             home and device grid
  request.html          new-device request form
  devices/              one HTML page per device
  shared/workbench.html shared log + chart panel
src/
  app.js                state, routing, events, device orchestration
  protocols.js          command / telemetry dispatch
  device-registry.js    device registry
  page-loader.js        async HTML fragment loader
  chart.js              Canvas 2D real-time chart
  echarts-charts.js     ECharts waveform preview
  config.js             app metadata
  transports/           serial / websocket / mqtt sessions
  devices/              per-device drivers
  modbus/modbus.js      Modbus RTU framing
  hart/hart.js          HART framing
  framing/              generic frame parsing (lines, header/tail, CRC16)

Devices and transports are kept separate. Adding a new device is usually: a driver file in src/devices/, an entry in device-registry.js, and a page in pages/devices/. See CONTRIBUTING.md for details (the contributing guide is in Chinese).

AOMaster register map

Addr	R/W	Meaning
0x0000	R/W	Signal type (current / voltage)
0x0001	R/W	Waveform: 0=const 1=step 2=ramp 3=square 4=triangle 5=sine
0x0002	R/W	Setpoint / low value
0x0003	R/W	High value / step hold time
0x0004	R/W	Period (ms) / cycle count
0x0005	R/W	Duty cycle × 10
0x0006	R	Actual output (readback)
0x0007+	R/W	Step sequence values

Default poll interval is 50 ms. In step mode the header is written first, then the sequence values.

Custom device

If your device isn't built in, the Custom page lets you describe it without writing JS:

• Output range, unit, step
• Send template with {value}, {value:2}, {unit} placeholders
• Parser: regex, JSON path, HEX offset, Modbus payload
• Scaling: parsed × scale + offset

Status

modusignal is actively maintained. New devices and parsers land regularly — see open issues for what's being discussed and feel free to chime in. If you'd like a device supported but don't want to write the driver yourself, open a request with the protocol doc, sample frames, and default connection parameters.

Contributing

PRs that add devices or improve existing drivers are welcome. Please read CONTRIBUTING.md first (Chinese; English version coming).

License

Apache License 2.0. See LICENSE.txt.

If modusignal saved you an afternoon of fighting with a vendor installer, a star helps other people find it.

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modusignal · 中文说明

浏览器里的设备调试台，纯静态前端，没有上位机要装、没有后端要起。打开网页、选设备、连上、看原始报文、手动发命令、看实时曲线，就这样。

一个标签页，一根线，跟设备直接对话。

适用场景

• 临时调一块 Modbus RTU 板子，不想装某厂家 200MB 的上位机
• 进车间带个 USB 转 485，笔记本插上就是 HART 调试工具
• 新设备走 WebSocket 或 MQTT，想边看流量边看曲线
• 把链接发给同事，比发 setup.exe 省事
• 内部协议没有现成工具，用 自定义设备 页面拼一个，不用写 JS

不适合：长时间数据采集、生产监控、SCADA。这是个调试工具。

内置设备

设备	传输	默认参数	说明
AOMaster	串口	115200 8N1	4-20mA / 0-10V 信号源，6 种波形
Modbus RTU	串口	9600 8N1	读写保持 / 输入寄存器
HART	串口	1200 8O1	设备搜索、通用命令、PV/SV/TV/QV
WebSocket	WebSocket	—	JSON / HEX / Modbus 报文调试
MQTT	MQTT over WS	—	发布订阅、QoS、保留消息、统计
自定义设备	任意	—	模板 + 解析规则，无需写代码

切设备时通讯方式和参数会跟着自动切换。

跑起来

开发模式不用构建，起一个静态服务即可：

python -m http.server 4173

用 Chrome / Edge 打开 http://localhost:4173。

要发布的话：

npm install
npm run build
npm run preview

构建脚本是 scripts/build.mjs（基于 esbuild），产物在 _site/。

离线使用

适合在笔记本、工控机或现场环境拷贝一份，无需联网拉代码。

获取离线包

• 每次推送到 main：打开 Actions → Offline package，在最新一次运行里下载 Artifact modusignal-offline-<版本>.zip。
• 打 v* 标签发布：在 Releases 下载 modusignal-offline-<标签>.zip。

本地运行

解压后双击 start-modusignal.bat（Windows）或运行 start-modusignal.sh（macOS/Linux），会自动起服务并打开浏览器。

也可手动执行：

python -m http.server 4173

用 Chrome / Edge 打开 http://localhost:4173。串口功能需在 localhost 或 HTTPS 下使用。

自己打包

npm install
npm run build:offline

产物在 _release/modusignal-offline-<版本>.zip（系统无 zip 命令时为 .tar.gz）。解压目录内的 OFFLINE.txt 有简要说明。

浏览器要求

功能	浏览器
串口（Web Serial）	Chrome / Edge 89+，需要 HTTPS 或 localhost
WebSocket	现代浏览器都行
MQTT over WebSocket	现代浏览器都行

Firefox 和 Safari 没有 Web Serial，串口设备用不了，其它功能正常。

项目结构

英文版的 Architecture 表已经列得很清楚了，这里不重复。简单说就是：设备层和传输层分开，加新设备 = 写一个驱动 + 注册 + 加一个页面，详见 CONTRIBUTING.md。

AOMaster 寄存器表

地址	读写	含义
0x0000	R/W	信号类型（电流 / 电压）
0x0001	R/W	波形：0=恒定 1=阶跃 2=斜坡 3=方波 4=三角 5=正弦
0x0002	R/W	设定值 / 低值
0x0003	R/W	高值 / 阶跃保持时间
0x0004	R/W	周期（ms）/ 循环次数
0x0005	R/W	占空比 × 10
0x0006	R	实际输出（回读）
0x0007+	R/W	步进序列值

默认轮询周期 50ms，步进模式先写头部再写序列值。

自定义设备

不想写 JS 也能配一个驱动出来：

• 输出范围、单位、步长
• 发送模板，支持 {value}、{value:2}、{unit} 占位符
• 解析规则：正则、JSON 路径、HEX 偏移、Modbus 载荷
• 数值换算：解析值 × 比例 + 偏移

项目状态

仍在持续迭代。新设备和解析能力会陆续加进来，欢迎在 issues 里讨论你想要的功能。需要新设备但不方便自己写驱动的，提一个 issue 附上协议文档、报文样例和默认连接参数即可。

贡献

欢迎 PR 增加设备或修复驱动，提交前请看 CONTRIBUTING.md。

许可证

Apache License 2.0。

如果 modusignal 帮你省下了一个下午跟厂家上位机较劲的时间，点个 star 能让更多人看到它。

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_{by 飞起小鹏 · modusignal.cn}