ApplicationsDecember 4, 2020

Edge-located HMIs drive new wave of Industry 4.0

A single device offers a wide variety of apps and dashboards for machine visualization and analysis.

Unified HMIs installed at the automation edge effectively connect users to their data by bridging OT plant data with workflows and IT tools. Advances will improve machine performance, reduce downtime, enable greater profitability, and fuel connected enterprises through the Industry 4.0 revolution.

The rising tide of Industry 4.0 is marked by surging data and cloud connectivity demands, as machine builders and manufacturers expect their plant floor process data to be available at all times from anywhere.

While digitalization and connectivity has always been viewed to be competitive advantages in manufacturing, they are now imperatives for achieving profitability, longevity, and responsiveness to rapidly evolving market trends.

Each app has its own container, hosted by a unified HMI’s docker.

Each app has its own container, hosted by a unified HMI’s docker.

Fortunately for machine builders, connected components are in abundance, and it is easier than ever to equip machines with smart sensors, variable frequency drives, and other intelligent components. However, transmitting data effectively from these devices to the cloud remains a challenge.

Unified human-machine interfaces (HMIs), located at the automation edge on the plant floor, are positioned to address this issue. Equipped with modern IT capabilities, unified HMIs make it easy to efficiently transfer data, enabling machine builders to deploy apps and centrally monitor one machine or a fleet. Availability of these IT capabilities in the industrial operations technology (OT) space accelerates machine efficiency improvement efforts.

Bandwidth and security issues

Internet of things developments are making it possible to connect remotely to numerous smart devices. Direct connection from device to cloud is often favorable in the consumer electronic space or for remote industrial applications where an edge controller is not present. However, in a plant setting with potentially hundreds of devices and sensors, direct connection to the cloud is usually not advisable due to bandwidth constraints and security concerns.

While a wide array of these devices in the industrial space support direct cloud connectivity, many machine components still require an intermediary device for pre-processing raw sensor data and converting it to cloud-friendly packets. Additionally, hundreds of sensors on a plant floor simultaneously broadcasting their data for external consumption can clog up the network, creating bandwidth and latency issues.

Even if data flows smoothly in both directions between plant floor and cloud, communication must be encrypted to ensure safe operation and protect sensitive information.
Moreover, most modern plants require a PC-based solution to collect, store, and interpret historical performance data for optimizing production. If all sensor data moves directly to the cloud, data aggregation must take place outside the confines of the plant floor, introducing more data integrity risk than is present while the data is closer to its original source.

Modern HMIs provide solutions

Machine builders can simulate proposed production changes prior to implementation.

Machine builders can simulate proposed production changes prior to implementation.

To address these concerns, manufacturers need an edge device on the plant floor to make efficient use of bandwidth in communications outside the plant, and to ensure secure data transactions. By processing data on the plant floor closer to its source, this type of component improves data integrity compared to processing in the cloud.

Though essential, the reliable movement of data from plant floor to cloud is only part of the need. Engineering, operations, and maintenance staff alike must be able to effectively visualize, analyze, and interact with machines to keep the plant running in an efficient manner, and unified HMIs at a network’s edge facilitate these functions.

Unified HMIs provide different capabilities than standard edge controllers with built-in apps for managing edge devices and data, and they bring advanced IT capabilities to the machine level in a cost-effective manner. When implemented, they serve as a central repository for data across the plant floor, enabling direct visualization and analysis of machine health and performance through a single interface. Compared to direct cloud connection of individual sensors, unified edge HMIs are less complicated to implement and more feature-rich out of the box, adding capabilities to plant-floor data processing.

Configuration and usage

Acting as a bridge between OT and IT, unified HMIs are automation infrastructure agnostic, and their applications can scale as plant floor layouts evolve. This is largely in part to a wide variety of applications available for managing and interacting with machines. While developers have a host of tools available for custom app creation on unified HMIs, they are also equipped with a wide selection of built-in, scalable edge apps.

In light of the headache-inducing challenge of managing application dependencies and compatibility across devices, unified HMIs use docker and container structure to alleviate this issue, freeing developers to focus on app logic and functionality. This makes unified HMI apps heavily configurable, as opposed to programmable, because the underlying infrastructure is already vetted.

Containerization wraps up all dependencies for an app into a single package, allowing it to be deployed to any device, without the need for a checklist of external resource requirements on the target. It is similar to virtualization of a personal computer (PC)—where an operating system (OS) and its entire file system are stored in a directory, and can be run without extensive external dependencies—though containers require lower overhead than virtual machines (VMs).

A docker engine running on a device’s OS enables the storage and execution of multiple containers. As a container is to a VM, so an HMI’s docker is to a host PC’s hypervisor.
In addition to using pre-built apps, machine builders can develop their own apps utilizing a unified HMI’s docker engine. The docker incorporates security intrinsically, another advantage enabling focus on app development and less time spent on building and maintaining infrastructure.

For machine builders and end users short on time, there is likely already ‘an app for that’. Native and third-party apps are available for purchase to run on unified HMIs, accomplishing tasks such as:

  • Performing advanced production algorithms and calculations
  • Connecting to data from multiple sources over multiple protocols
  • Visualizing data
  • Automating workflows
  • Managing inventory
  • Analyzing machine and drive health, and calling out predictive maintenance
  • Analyzing performance and creating insights
  • Creating notification pipelines and sending alerts
  • Simulating production with digital twin

Furthermore, unified HMIs are repositories for data collection, analysis, storage, and forwarding. With the right apps, users can connect to automation controllers, drives, OPC UA devices, and other edge devices. Using the MQTT protocol, these devices can efficiently publish data to the cloud, consuming minimal network resources.
Due to their multilingual properties, unified HMIs perform well as interfaces for establishing key performance indicators (KPIs) and measuring actual production output from multiple machines. Unified HMIs also eliminate the need for PCs in many applications because they can execute many of the IT functions performed by PCs within their industrially-hardened HMI housing.

Device and app management

Adding another IT characteristic increasingly making its presence known in OT, unified HMIs include enterprise management. Machine builders and manufacturers can centrally manage devices and apps from on or off premise through a web-based interface independent of the HMI automation project file. This can be done from any device capable of hosting a web browser, such as a laptop, smartphone, or tablet.

This model provides the flexibility to store apps and licenses on servers, remotely deploy or update apps without modifying machine-level functionality, apply security patches, and manage content of all unified HMIs across the enterprise. Communication among devices is encrypted, and HMIs can be configured for automatic system backup to prevent data loss.

Apps run in the background fulltime with their hooks in the docker—independently of the OS running the classical HMI automation project also present on a unified HMI—so a change in app configuration does not impact HMI runtime execution. This provides the flexibility to update apps on a regular basis without concern of modifying the automation program file.


Machine builders can remotely push software updates to machines around the world.

Machine builders can remotely push software updates to machines around the world.

For an industrial heater manufacturer, struggling to keep up with growing demands from its stakeholders, implementing Siemens WinCC Unified HMI software and panels enabled it to deliver greater functionality and performance to its users.

This empowered the manufacturer to develop its own apps for machine and performance analysis, and for maintenance support. The HMI’s docker ensured app security, and it saved development time because the pre-built container infrastructure allowed attention to be placed on app functionality.

Using unified HMIs’ remote management capabilities, the machine builder was able to remotely push updates to machines around the world whenever they released a new revision, comparable to app updates on a smartphone or patches on a PC.

Unified HMIs’ native support for MQTT made cloud connectivity possible, while OPC UA protocol support enabled users to connect their new machine with other machines in their facilities, and with intelligent devices.

Continually improving

While industry grows more agile and geographically dispersed, machine builders are pursuing always-on access to data. Unified HMIs installed at the automation edge effectively connect users to their data by bridging OT plant data with workflows and IT tools, phasing out the need for industrial PCs in many applications.

This consolidation of functionality is already driving Industry 4.0 as machine builders are empowered to:

  • Connect to their data from anywhere
  • Consolidate traditionally separated OT and IT devices for data processing and access into a unified HMI
  • Integrate machine performance data directly with business process workflows
  • Deploy out-of-the-box or customized apps for interaction with their data
  • Utilize app containers to streamline functionality and security, and alleviate OS and firmware compatibility issues

As unified HMIs evolve and continue to simplify hardware infrastructure, more and more manufacturers are relying on these devices to branch out further, supporting an increased breadth of factory-floor communication protocols. These advances will improve machine performance, reduce downtime, enable greater profitability, and fuel connected enterprises through the Industry 4.0 revolution.

Ramey Miller, the HMI/Edge product marketing manager, Siemens Industry.