IoT Node.js Modbus Backend Service

A robust Node.js backend service designed to ingest Modbus meter data via a REST API and store it in a PostgreSQL database. This service supports running as a Windows Service for continuous operation.

Features

• REST API: Accepts Modbus meter data via HTTP POST requests.
• Database Integration: Stores parsed meter readings in a PostgreSQL database.
• Windows Service: Built-in support for installation as a background Windows Service (ModbusMeterService).
• Data Processing: automatically calculates power factor and handles data type conversions.

Prerequisites

Before running this project, ensure you have the following installed:

• Node.js (v14 or higher recommended)
• PostgreSQL

Installation

1. Clone the repository (or extract the project files):

   git clone <repository-url>
   cd IoT-nodejs-modebus-backend-service

2. Install dependencies:

   npm install

Configuration

1. Environment Variables: Create a .env file in the root directory if it doesn't exist, or configure your environment with the following variables. Defaults are provided in the code if not specified.

   PORT=5000
   DB_USER=postgres
   DB_HOST=localhost
   DB_NAME=Building_Automation_Management_System
   DB_PASSWORD=your_password
   DB_PORT=5432

2. Database Setup: Ensure your PostgreSQL database exists and has the required schema. Run the following SQL to create the table:

   CREATE SCHEMA IF NOT EXISTS bms;
   
   CREATE TABLE IF NOT EXISTS bms.modbus_meter_data (
       id SERIAL PRIMARY KEY,
       meter_id VARCHAR(255),
       received_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
       voltage_a NUMERIC,
       voltage_b NUMERIC,
       voltage_c NUMERIC,
       current_a NUMERIC,
       current_b NUMERIC,
       current_c NUMERIC,
       power_a NUMERIC,
       power_b NUMERIC,
       power_c NUMERIC,
       total_power NUMERIC,
       energy_import NUMERIC,
       energy_export NUMERIC,
       frequency NUMERIC,
       pf_a NUMERIC,
       pf_b NUMERIC,
       pf_c NUMERIC,
       pf_total NUMERIC,
       current_demand NUMERIC,
       max_demand NUMERIC,
       raw_payload JSONB
   );

Usage

Running Locally (Development)

To start the server in development mode with auto-reload:

npm run dev

The server will start on http://localhost:5000 (or your configured PORT).

Running as a Windows Service

To install and start the application as a Windows Service:

1. Open a terminal as Administrator.
2. Run the installation script:

   node service_install.js

3. The service ModbusMeterService will be installed and started automatically.

To uninstall the service (if needed in the future), you would typically use a similar script using svc.uninstall().

API Documentation

Ingest Meter Data

• URL: /api/modbus/meter-data
• Method: POST
• Content-Type: application/json

Request Body Example

The API expects a JSON payload with the following structure (keys map to specific database columns):

{
  "meter": "Meter_001",
  "Ua": 230.5,
  "Ub": 231.0,
  "Uc": 229.8,
  "Ia": 10.5,
  "Ib": 11.2,
  "Ic": 10.8,
  "Pa": 2400,
  "Pb": 2500,
  "Pc": 2450,
  "Pt": 7350,
  "PositiveEnergy": 15000.5,
  "NegativeEnergy": 50.0,
  "freq": 50.0,
  "PF_A": 95,
  "PF_B": 96,
  "PF_C": 94,
  "PF_T": 95,
  "CDt": 7000,
  "MDt": 8000
}

Response

• Success (200 OK):

  {
    "success": true
  }

Project Structure

• server.js: Main entry point of the application.
• service_install.js: Script to install the app as a Windows Service.
• controllers/: Contains logic for handling requests (e.g., modbusController.js).
• routes/: Defines API endpoints (e.g., modbusRoutes.js).
• daemon/: Directory where service logs and executables are stored after installation.