Improve communications efficiency and reduce reliance on IT.


Included with groov EPIC and groov RIO is MQTT communication, with both string and Sparkplug B payloads. MQTT (formerly MQ Telemetry Transport) is a publish-subscribe (pub-sub) protocol that’s suited to many IIoT applications because of its architecture.

In a pub-sub architecture, a central server called a broker handles all data. MQTT clients can publish data to the broker or subscribe to get data from it (or both). Clients who publish data send it only when the data changes (report by exception). Clients who subscribe to data automatically receive it from the broker only when it changes.

Contrast this with a request-response (or poll-response) architecture. There the client and server must be connected, because the client requests data directly from the server. The client doesn’t know when the data changes, so it must request it at regular intervals.

MQTT pub-sub offers three main advantages over request-response for IIoT applications:
  • Network traffic is reduced overall, because data is published and sent only when it changes, rather than at regular intervals.
  • Because the broker is a central source for data, servers don’t have to strain to serve multiple clients. And even remote devices with irregular connections or low bandwidth can publish or subscribe to data.
  • For data publishers, there’s another important advantage: all data originates in the device and is published using an outbound connection. Most firewalls block inbound traffic (for example, an external client requesting data from an internal server), but they allow device-originated, outbound connections. 

With device-originated connections, once the connection is initiated, data can travel in both directions. For example, whether a groov EPIC is publishing or subscribing to data, the EPIC initiates the connection. That's an outbound connection, which the firewall would allow. Once the connection is made, data can travel bidirectionally. 

In groov EPIC and groov RIO, you can use MQTT from within groov Manage, or through Ignition/Ignition Edge (available in GRV-EPIC-PR1, GRV-EPIC-PR2, and GRV-R7-MM2001-10).

“We disconnected a controller and within a millisecond the system reported the failure. It really is that easy: change a variable and it shows up in the broker, then on your mobile phone.” 

- Frank Fisher, engineering superintendent, Waterford DPW

 

A groov EPIC Architecture Example using MQTT




 

MQTT Transmission with either a strings payload or Sparkplug-B payload, available through groov EPIC and groov RIO, offers advantages for both on-premises and remote data communication.

In the diagram, groov EPIC systems in industrial areas connect to sensors and actuators through their own I/O and through other PACs, PLCs, and RTUs, and publish and subscribe to data through the MQTT broker.

At the main site, Ignition Edge and a groov EPIC also publish and subscribe data through the broker, while providing database connectivity and system visualization.

MQTT Advantages

  • Designed for industrial systems
  • Device-originating communications
  • Centralized security management at broker
  • Data reported by exception, on change only
  • Lightweight data communications
  • Fewer communication links
  • Much less traffic on network
  • Ideal for intermittent connections
  • Broker can be located onsite or offsite
  • No need for VPNs or open firewall ports
  • Less reliance on IT departments

Additional Resources for MQTT