Examples

Example 1: Subscribe file -> publish event

Requirement

• FTP Server

1.1 FTP Datasource

If not already done so, then create a FTP data source on your device. For that:

• navigate to "devices"
• select your device
• press on "+ Data Source"
• fill out the configuration to your FTP server

1.2 Edge Function

VL.subscribeFile = (dataString) => {
  VL.publishMeasurements([{ name: 'Datatype_1', value: dataString[0] }]);
};

VL.reportDataPointMetadata = () => {
  return [{ name: 'Datatype_1', variable_type: 'FLOAT', unit: '°C' }];
};

Example 2: Subscribe measurement -> publish measurement event

This example shows the conversion of Celsius to Fahrenheit

2.1 Datasource

If not already done so, then create a data source on your device. For that:

• navigate to "devices"
• select your device
• press on "+ Data Source"
• fill out the configuration for your data source

2.2 Edge Function

function celsiusToFahrenheit(celsius) {
  return (celsius * 9) / 5 + 32;
}

const myFilterOptions = {
  filter: { dataSource: { protocol: 's7' }, data: ['sensors_qaTemperature'] }
};

VL.subscribeMeasurements = (message) => {
  let filteredMessage = VL.filter(message, myFilterOptions);
  if (Object.values(filteredMessage).length === 0) {
    return;
  }

  let sensorTemperaturData = filteredMessage.data.find(
    (d) => d.name === 'sensors_qaTemperature'
  );

  let tmpF = celsiusToFahrenheit(sensorTemperaturData?.value);

  VL.publishMeasurements([{ name: 'temperatureInF', value: tmpF }]);
};

VL.reportDataPointMetadata = () => {
  return [{ name: 'temperatureInF', variable_type: 'FLOAT', unit: '°F' }];
};

Example 3: Subscribe measurement -> publish measurement event

This example calculates the active power

3.1 Datasource

If not already done so, then create a data source on your device. For that:

• navigate to "devices"
• select your device
• press on "+ Data Source"
• fill out the configuration for your data source

3.2 Edge Function

function calculateActivePowerThreePhase(voltage, current, phaseAngle) {
  const phaseAngleInRadians = phaseAngle * (Math.PI / 180);

  const activePower =
    Math.sqrt(3) * voltage * current * Math.cos(phaseAngleInRadians);

  return activePower;
}

const myFilterOptions = {
  filter: { dataSource: { protocol: 's7' }, data: ['VoltageL1N, CurrentL1'] }
};

VL.subscribeMeasurements = (message) => {
  let filteredMessage = VL.filter(message, myFilterOptions);
  if (Object.values(filteredMessage).length === 0) {
    return;
  }

  let sensorTemperaturData = filteredMessage.data.find(
    (d) => d.name === 'sensors_qaTemperature'
  );

  let voltage = 230; // in Volts
  let current = 10; // in Amperes
  let phaseAngle = 30; // in Degrees

  let activePower = calculateActivePowerThreePhase(
    voltage,
    current,
    phaseAngle
  );
  VL.publishMeasurements([{ name: 'activePower', value: tmpF }]);
};

VL.reportDataPointMetadata = () => {
  return [{ name: 'activePower', variable_type: 'FLOAT', unit: '°F' }];
};