As devices and equipment are increasingly embedded with sensing and networking capabilities, the industrial internet of things (IIoT) is opening up rich reporting and monitoring opportunities to enable intelligent management decisions and process optimization in industrial applications ranging from transportation to utilities to factory automation.

For example, sensors embedded in packaging and trucks thoroughly and accurately track assets and vehicles in fleet management applications, allowing resources to be optimally deployed by logistics managers. Networked sensors in electrical generation and transmission equipment monitorpower quality data to quickly detect and pinpoint the location of faults.

And in factories, sensors embedded in machine elements provide process data for operating status feedback, analytics or predictive maintenance. For instance, readings from a sensor embedded in a pneumatic valve can calculate the amount of pressurized air consumed by the valve. Analysis of those measurements uncovers trends that indicate a problem exists. If the flow is too low, the supply of air may be blocked somewhere along the line; too high, and the valve might have a leak. By identifying and fixing problems early with preventive maintenance, major failures that result in costly downtime can be avoided.

Establishing an IIoT network to collect and report data from sensors installed in every machine in a factory provides a complete view of a production operation to help managers optimize processes, solve problems, improve efficiencies and reduce costs.

IIoT communication process overview

To understand how an IIoT network gathers and broadcasts process data, consider an example based on the IoT communication system developed by Beckhoff, a German manufacturer of industrial automation and control solutions. The following steps provide a general overview of the IIoT communication process.

  1. Sensors embedded in equipment throughout a factory are networked to modular I/O terminals.
  2. The I/O terminals are connected to programmable logic controllers (PLCs) loaded with IoT communication software.
  3. The IoT software publishes process data received by the PLCs using a communication protocol like Message Queuing Telemetry Transport (MQTT) or Advanced Message Queuing Protocol (AMQP) to a broker residing in a private or public cloud service.
  4. The broker then sends the data to subscribers, such as mobile devices or computers owned by plant operators, according to the topics (types of data) they signed up for.

Example: Beckhoff IoT communication system

For a more detailed view into how IIoT networks function, examine how Beckhoff’s TwinCAT automation suite uses IoT communication to share process data.

In Beckhoff’s system, the default protocol over which devices communicate is EtherCAT (Ethernet for control automation technology), Beckhoff’s Ethernet-based fieldbus protocol. Sensors gathering process data from equipment throughout the factory are networked to modular I/O EtherCAT terminals.

[Discover products equipped with Ethercat interfaces on Engineering360.]

Beckhoff’s IoT Data Agent acts as a gateway application to gather process data and send it to an MQTT broker in the cloud for transmission to subscriber devices. Source: BeckhoffBeckhoff’s IoT Data Agent acts as a gateway application to gather process data and send it to an MQTT broker in the cloud for transmission to subscriber devices. Source: Beckhoff

The system is not limited, however, to EtherCAT communications alone. The I/O terminals also interface with devices connected to a wide range of Fieldbuses through bus couplers attached to the terminal. Bus couplers serve as the interface between EtherCAT and equipment that communicates over conventional Fieldbus protocols like CANopen, DeviceNet, PROFIBUS, as well as other industrial Ethernet protocols like EtherNet/IP and PROFINET. Multiple I/O terminals, collecting data from thousands of sensors from across the factory, can be linked by EtherCAT.

The sensor data is fed from the I/O terminals over EtherCAT to PLCs. Beckhoff’s system uses PC-based control technology instead of traditional hardware PLCs; PLC functionality is enabled by PLC software runtime systems running on industrial or embedded Windows PCs equipped with high-performance processors. This approach provides additional flexibility and scalability for control applications.

[Search Programmable Logic Controllers (PLCs) by specification on Engineering360.]Beckhoff’s C69xx series of industrial PCs are designed to be mounted in control cabinets. Installed with TwinCAT automation and IoT communication software, they become highly functional PLCs capable of reporting process data to remote devices. Source: BeckhoffBeckhoff’s C69xx series of industrial PCs are designed to be mounted in control cabinets. Installed with TwinCAT automation and IoT communication software, they become highly functional PLCs capable of reporting process data to remote devices. Source: Beckhoff

IoT communication software can be installed on these PC-based control systems to report process data to remote devices. This software, called TwinCAT IoT Communication, includes the drivers and PLC library containing the necessary functions to enable IoT communication over MQTT.

A TwinCAT IoT Data Agent is also available installable directly on controller PCs or gateway computers to receive process data from sensors. The Data Agent handles data from Beckhoff controllers communicated over the company’s TwinCAT ADS (Automation Device Specification), or from third-party devices over the standardized OPC UA protocol.

[Discover Data Acquisition Systems and Instruments and I/O Modules and Instruments on Engineering360.]

The IoT software publishes data over MQTT to a broker residing in a private or public cloud service. Public cloud services compatible with Beckhoff’s TwinCAT IoT Communication system include the following IoT platforms:

  • Amazon AWS IoT
  • Microsoft Azure IoT Hub
  • IBM Watson IoT
  • MathWorks ThingSpeak

The MQTT broker running in the cloud forwards the data to subscribers according to the topics they signed up for. Subscribers include mobile devices like smartphones running the TwinCAT IoT Communicator App and computers configured to receive MQTT data.Beckhoff’s PC-based PLCs running the TwinCAT Runtime send process data over MQTT protocol via the TwinCAT IoT Communicator to a message broker, which then forwards data to mobile devices running the TwinCAT IoT Communicator App. Source: BeckhoffBeckhoff’s PC-based PLCs running the TwinCAT Runtime send process data over MQTT protocol via the TwinCAT IoT Communicator to a message broker, which then forwards data to mobile devices running the TwinCAT IoT Communicator App. Source: Beckhoff

Beckhoff’s TwinCAT Analytics Workbench allows users to select process data to track. The tool utilizes multiple algorithms to provide visibility of machine operations, including minimum, maximum and mean values, lifetime, life count and cycle time monitoring. Reported over MQTT, this data can be displayed through HTML 5 dashboards to machine operators and production managers for a 24/7 view of the production process.

MQTT communication can be secured by Transport Layer Security (TLS) to require username and password authentication and encrypt data transmitted between users and the message broker. Depending on the cloud service, Beckhoff’s IoT communication system supports both TLS-PreSharedKey (TLS-PSK) as well as certificates issued by trusted certificate authorities.

[Read What is MQTT? for more information on how the messaging protocol works.]

Resources

TC3 IoT Communication (MQTT) Manual [PDF] | Beckhoff Automation

Microsoft Azure IoT Reference Architecture [PDF] | Microsoft