title: Error connecting Module to Edge Hub using Node sdk- NotConnectedError: unable to get local issuer certificate
body: <p>Edge Module node client is unable to connect to Edge Hub over MQTT. It throws a cert error - <code>NotConnectedError: unable to get local issuer certificate</code>. </p>
  
  <p>Cert is set an option for the client,</p>
  
  <pre><code>var certFile = process.env.EdgeModuleCACertificateFile;
  var connectionString = process.env.EdgeHubConnectionString
  var Protocol = require('azure-iot-device-mqtt').Mqtt;
  var Client = require('azure-iot-device').Client;
  var client = Client.fromConnectionString(connectionString, Protocol);
  
  var options = {
      ca: fs.readFileSync(certFile,'utf-8').toString(),
  };
  client.setOptions(options,()=&gt;{
      console.log('Client transport option set');
  });
  client.open(connectCallback);
  </code></pre>