in sensor/index.js [55:72]
setInterval(function(){
//calculate randome values for each sensor reading
msg.pH = RandomValue(50, 100) / 10;
msg.temperature = RandomValue(480, 570) / 10;
msg.salinity = RandomValue(200, 350) / 10;
msg.disolvedO2 = RandomValue(40, 120) / 10;
msg.timestamp = new Date().getTime();
//publish the sensor reading message
var topic = VALUE_TOPIC.replace('[thingName]', sensor.settings.clientId);
device.publish(topic, JSON.stringify(msg));
console.log('published to telemetry topic ' + topic + ' ' + JSON.stringify(msg));
}, sensor.frequency);