RawDataWorker

Arduino-based current-transformer data collector that publishes machine "working / idle" state to the AWM monitoring system over HTTP.

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Overview

RawDataWorker is a small hardware agent that turns an ordinary current transformer (CT) into a non-invasive machine activity sensor. It measures the RMS current drawn by the machine's power line, decides whether the machine is currently working or idle, and pushes the state to the AWM backend via a plain HTTP POST.

The project is part of a larger monitoring stack:

┌──────────────┐   HTTP/JSON   ┌──────────────┐   SignalR   ┌────────────┐
│ RawDataWorker│ ────────────► │     AWM      │ ──────────► │  Dashboard │
│  (Arduino)   │               │  (ASP.NET)   │             │  (browser) │
└──────────────┘               └──────────────┘             └────────────┘

This repository contains only the firmware and hardware artifacts. The backend lives in a separate repository.

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How it works

1. The current transformer is clamped onto one phase of the machine's power cable. It outputs a small AC voltage proportional to the line current.

2. The Arduino samples the CT via EmonLib::calcIrms() and computes the RMS current.

3. Estimated active power is P ≈ U · I (nominal 230 V).

4. A simple debouncer requires N consecutive equal readings before the state is considered stable.

5. When the stable state differs from the last state that was successfully sent, the Arduino opens a TCP connection to the AWM backend and issues:

   POST /api/Wincc/updateMachineStatus HTTP/1.1
   Host: 192.168.10.200
   Content-Type: application/json
   Content-Length: 87
   Connection: close
   
   {"machineName":"Danobat","Condition":true,"current":3.42,"power":787}

6. The server replies 200 OK with a body indicating whether the state was actually changed. The Arduino treats any 200 OK as success.

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Hardware

Component	Notes
Arduino Mega 2560	Any AVR board with enough RAM will do
Ethernet Shield W5100	Or a compatible W5100/W5500 module
SCT-013-030 CT	30 A / 1 V output; adjust CT_CALIBRATION to taste
Burden resistor	Already built into the SCT-013-030
3D-printed enclosure	See hardware/case

Wiring

⚠️ The current transformer must be clamped around a single phase conductor, not around the whole cable. Otherwise the magnetic fields cancel out and you will read ~0 A.

Photos of the assembled device: hardware/photos.

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Firmware

Dependencies

• EmonLib — current measurement
• Ethernet — W5100/W5500 networking
• SPI — bundled with the AVR core

Build & flash

1. Open firmware/RawDataWorker/RawDataWorker.ino in the Arduino IDE.
2. Select Tools → Board → Arduino Mega or Mega 2560.
3. Select the correct serial port.
4. Adjust the configuration block at the top of the sketch (IP addresses, MACHINE_NAME, CT_CALIBRATION, …).
5. Upload and open the Serial Monitor at 9600 baud.

Configuration

All tunables live in a single block at the top of the sketch:

Constant	Purpose
mac, localIp, …	Static network configuration of the Arduino
serverIp, serverPort	AWM backend address
MACHINE_NAME	Identifier sent in every payload
CT_CALIBRATION	EmonLib calibration coefficient; tune to your CT
CURRENT_THRESHOLD_A	Current above which the machine is considered active
MAINS_VOLTAGE_V	Nominal voltage used for the power estimate
NEED_STABLE_READINGS	Number of equal readings to confirm a state change
MEASURE_INTERVAL_MS	Sampling period
HTTP_TIMEOUT_MS	Socket timeout for the outgoing request

Serial output example

========================================
===     RAW DATA WORKER (current)    ===
========================================
Sensor... OK
Ethernet... OK, IP=192.168.10.177
Server: 192.168.10.200:5050
========================================
0.02 A | Stop 1/3
0.02 A | Stop 2/3
0.01 A | Stop 3/3
3.41 A | Work 1/3
3.44 A | Work 2/3
3.39 A | Work 3/3 -> sending... [CHANGED] OK

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Protocol

See docs/protocol.md for the full request/response contract, error handling and retry behaviour.

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Pre-built firmware

If you just want to flash a working binary without setting up the Arduino toolchain, grab RawDataWorker.ino.standard.hex from the latest release.

The pre-built binary uses the default configuration from the source code. If you need a different IP address, machine name, or CT calibration, build the sketch yourself using the instructions above.

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Design notes & known limitations

• Blocking HTTP. While the request is in flight (up to HTTP_TIMEOUT_MS), the loop does not sample. At a 1 Hz rate this is acceptable; if higher frequencies are needed, the HTTP client should be rewritten as a non-blocking state machine.
• P ≈ U · I. This is an apparent power estimate. For machines with poor power factor the real active power may be lower. A true energy meter or a PZEM-004T module would give real power directly.
• EmonLib is in maintenance mode. A future revision may switch to EmonLibCM or EmonLibDB for continuous, interrupt-driven sampling.
• No TLS. The device talks plain HTTP on a trusted industrial LAN.

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Repository layout

.
├── .github/workflows/    CI: build the sketch on every push
├── firmware/
│   └── RawDataWorker/    Arduino sketch (folder name = sketch name)
├── hardware/
│   ├── case/             3D enclosure drawings
│   ├── photos/           Photos of the assembled device
│   └── wiring/           Wiring diagram
├── docs/
│   └── protocol.md       HTTP contract between the device and AWM
├── .editorconfig
├── .gitattributes
├── .gitignore
├── LICENSE
└── README.md

The firmware/RawDataWorker/ folder has the same name as the .ino file inside it. This is required by the Arduino build system — the sketch name must match the folder name.

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License

MIT — see LICENSE.

Hardware artifacts (drawings, enclosure) are released under the same license unless stated otherwise.

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Author

Dmitry Kharchenko — C#/.NET backend developer with a soft spot for the hardware side of things.

• GitHub: @Dimo4ka174
• Email: Dmitry.Kharchenko.Dev@yandex.ru

This repository is a personal project. It does not contain any code, schematics, or data belonging to previous or current employers.