main.js

const EventEmitter = require('events');
const util = require('util');
let SerialPort = require('serialport');

let connectedToSmartMeter = false;
let constructor;

const parsePacket = require('./lib/parsePacket');
const debug = require('./lib/debug');
const config = require('./config/config.json');

function P1Reader(options) {
    if (typeof options !== 'object' || options.port == "" || options.baudRate == "" || options.parity == "" || options.dataBits == "" || options.stopBits == "") {
        console.error("Parameters 'port', 'baudRate', 'parity', 'dataBits' and 'stopBit' are required since version 2.x.x to instantiate the module");
    }

    if (options.debug) {
        debug.enableDebugMode();
    }

    // Overwrite serialport module when emulator mode is set
    if (options.emulator) {
        SerialPort = require('./lib/emulateSerialport');
        SerialPort.setEmulatorOverrides(options.emulatorOverrides);
    }

    constructor = this;

    EventEmitter.call(this);
    
    _setupSerialConnection(options.port, options.baudRate, options.parity, options.dataBits, options.stopBits);
}

util.inherits(P1Reader, EventEmitter);

module.exports = P1Reader;

/**
 * Setup serial port connection
 */
function _setupSerialConnection(port, baudRate, parity, dataBits, stopBits) {
    debug.log('Trying to connect to Smart Meter via port: ' + port + ' (BaudRate: ' + baudRate + ', Parity: ' + parity + ', Databits: ' + dataBits + ', Stopbits: ' + stopBits + ')');

    // Open serial port connection
    const sp = new SerialPort(port, {
        baudRate: baudRate,
        parity: parity,
        dataBits: dataBits,
        stopBits: stopBits
    });

    const connectionTimeout = setTimeout(() => {
        if (!connectedToSmartMeter) {
            debug.log('Could not establish a connection with the Smart Meter (connection timeout)');
            constructor.emit('error', 'Connection timeout');
        }
    }, 11000); // Set time for 11 seconds, since we should receive at least one message every 10 seconds from the Smart Meter

    let received = '';

    sp.on('open', () => {
        debug.log('Serialport connection opened, trying to receive data from the Smart Meter...');

        sp.on('data', data => {
            received += data.toString();

            const startCharPos = received.indexOf(config.startCharacter);
            const endCharPos = received.indexOf(config.stopCharacter);

            // Package is complete if the start- and stop character are received
            if (startCharPos >= 0 && endCharPos >= 0) {
                const packet = received.substr(startCharPos, endCharPos - startCharPos);
                const parsedPacket = parsePacket(packet);

                received = '';

                // Emit a 'connected' event when we have actually successfully parsed our first data
                if (!connectedToSmartMeter && parsedPacket.timestamp !== null) {
                    debug.log('Connection with Smart Meter established');
                    constructor.emit('connected');
                    connectedToSmartMeter = true;
                    clearTimeout(connectionTimeout);
                }

                debug.writeToLogFile(packet, parsedPacket);

                constructor.emit('reading-raw', packet);

                if (parsedPacket.timestamp !== null) {
                    constructor.emit('reading', parsedPacket);
                } else {
                    constructor.emit('error', 'Invalid reading');
                }
            }
        });
    });

    sp.on('error', (error) => {
        debug.log('Error emitted: ' + error);
        constructor.emit('error', error);
    });

    sp.on('close', () => {
        debug.log('Connection closed');
        constructor.emit('close');
    });
}