Failed to start xxx: TypeError: xxx is not a constructor at plugin.start

[petowa]

I have a simple requirement to output a pulse for every 1 m travelled on my RPi 4 Openplotter v3. I started with a simple js code but got stuck on the above error. There seems to be a version problem between Openplotter SignalK and the @signalk/client.
I have tried a LOT of things but to no avail. I have done a LOT of VBA programming but nothing before in js and it all looks a bit like Chinese to me.
I tried first as a non-plugin, just js code. That sort of worked but when I tried to make it a SK plugin things got really messy. AI has helped me to add error logging etc but the solution still eludes me.
Here is the top of my index.cjs:
///////////////////////////////////////////////
module.exports = function (app) {
const plugin = {};
let pulser;

plugin.id = 'signalk-speed-to-pulse';
plugin.name = 'Speed to GPIO pulse';
plugin.description = 'SignalK plugin that sends the speedOverGround to a GPIO pin as a pulse per m travelled';

plugin.start = async function (options) {
try {
console.log('Starting SpeedToPulse plugin with options:', options);

     // Dynamically import SpeedToPulse
     const { SpeedToPulse: importedSpeedToPulse } = await import('./signalk-speed-to-pulse.mjs');
     console.log('SpeedToPulse module imported successfully');
     SpeedToPulse = importedSpeedToPulse;

     // Instantiate SpeedToPulse
     pulser = new SpeedToPulse(options.pinNumber);
     console.log('SpeedToPulse instance created');

     // Set up event listeners
     pulser.on('error', (err) => {
        console.error('SpeedToPulse error:', err);
        // Optionally, handle the error or notify the user via SignalK
     });

     console.log(`SpeedToPulse started on pin ${options.pinNumber}`);
  } catch (error) {
     console.error('Failed to start SpeedToPulse:', error);
  }

};
..................

Here is my SpeedToPulse program:
////////////////////////////////////////////////////////
import { Gpio } from 'onoff';
import { EventEmitter } from 'events';
import { setTimeout } from 'timers';

class SpeedToPulse extends EventEmitter {
constructor(pinNumber) {
super();
this.pinNumber = pinNumber;
this.pin = null;
this.lastSpeed = { speed: 0, timestamp: Date.now() };
this.distance = 0;
this.client = null;

  this.initGPIO();
  this.setupSignalKClient();

}

initGPIO() {
try {
this.pin = new Gpio(this.pinNumber, 'out');
} catch (gpioError) {
console.error('Failed to initialize GPIO:', gpioError);
this.emit('error', 'GPIO initialization failed');
}
}

async setupSignalKClient() {
await this.loadSignalKClient();
this.client = new this.SignalKClient({
hostname: 'localhost',
port: 3000,
useTLS: false,
reconnect: true,
autoConnect: false,
notifications: false,
subscriptions: [
{
context: 'vessels.self',
subscribe: [
{
path: 'navigation.speedOverGround',
policy: 'instant'
},
],
},
],
});

  this.client.on('delta', (delta) => {
     this.handleSpeedUpdate(delta);
  });

  this.client.on('error', (err) => {
     console.error('Error with SignalK client in speedToPulse:', err);
     this.emit('error', 'Error in SignalK client in speedToPulse');
  });

  this.client.connect().catch((connectError) => {
     console.error('Failed to connect to SignalK server (speed-to-pulse):', connectError);
     this.emit('error', 'Failed to connect to SignalK server (speed-to-pulse)');
  });

}

async loadSignalKClient() {
try {
const module = await import('@signalk/client');
this.SignalKClient = module.SignalKClient;
} catch (error) {
console.error('Failed to load SignalK client module:', error);
this.emit('error', 'Failed to load SignalK client module');
}
}

handleSpeedUpdate(delta) {
if (delta.updates && delta.updates.length > 0) {
const speed = delta.updates[0].values[0].value;
const now = Date.now();
const deltaTime = (now - this.lastSpeed.timestamp) / 1000;
const deltaDistance = this.calculateDistance(speed, deltaTime);

     this.distance += deltaDistance;

     if (this.distance >= 1) {
        this.generatePulse();
        this.distance -= 1;
        // this.emit('delta', { distance: 1 }); // Emit event for each pulse
     }
     this.lastSpeed = { speed, timestamp: now };
  }

}

calculateDistance(speed, deltaTime) {
return speed * deltaTime;
}

generatePulse() {
if (this.pin) {
try {
this.pin.writeSync(1);
setTimeout(() => {
this.pin.writeSync(0);
}, 100);
} catch (error) {
console.error('Error generating pulse:', error);
this.emit('error', 'Error generating pulse');
}
}
}

cleanup() {
if (this.pin) {
this.pin.unexport();
}
}
}

export default SpeedToPulse;

Any help would be greatly appreciated

[tkurki]

Plugins can access Signal K data directly via server’s plugin apis, no need for the client. You would be better off starting from a blank plugin, then add data access and finally gpio.

https://demo.signalk.org/documentation/develop/plugins/server_plugin.html

…but if I were you I would probably use Node-RED plugin, as it is pretty well suited for this kind of task.

[petowa]

Thanks Teppo, I'll look into Node-Red. Regards, Paul Paul Peterson Principal Maintenance Engineer Engineering & Technical Consultants 0427 072 373

…

---- On Tue, 10 Sep 2024 16:49:34 +0800 Teppo Kurki ***@***.***> wrote --- Plugins can access Signal K data directly via server’s plugin apis, no need for the client. You would be better off starting from a blank plugin, then add data access and finally gpio. https://demo.signalk.org/documentation/develop/plugins/server_plugin.html …but if I were you I would probably use Node-RED plugin, as it is pretty well suited for this kind of task. — Reply to this email directly, #132 (comment), or https://github.com/notifications/unsubscribe-auth/AMTEWH33VADI3MDM6WLDAETZV2XB5AVCNFSM6AAAAABN56T2AOVHI2DSMVQWIX3LMV43URDJONRXK43TNFXW4Q3PNVWWK3TUHMYTANJZHE4DSNA. You are receiving this because you authored the thread.