Building reliable visualization and control for industrial edge applications
Increase manageability, flexibility, and reliability using
thin-client and virtualization architectures
By Jason Andersen
Industrial manufacturers understand that holding steady is rarely an option. This is because ongoing productivity improvements are a near-universal requirement. Manufacturers can achieve such improvements in many ways, with the most valuable upgrades enhancing several things simultaneously, perhaps across multiple levels of an organization. Today's automation experts are discovering that moving visualization and control functionality toward the industrial "edge" is helping them achieve better operations and improved maintainability, among other benefits.
Production and manufacturing industries have long employed supervisory control and data acquisition (SCADA) applications, human-machine interface (HMI) software, and other automation platforms, such as programmable logic controllers (PLCs) and process automation controllers (PACs). Progressive use of these systems reduces waste, increases uptime, and improves overall equipment effectiveness (OEE).
These systems require some level of "core" server and PC computing power to function, combined with local "edge" computing elements in the field to support visualization and control. With the right pieces in place, organizations attain maximum value. Data from smart field systems has a reliable path to flow to the core, while operators can access the key information required to run the factory in the best way (figure 1).
Standard commercial solutions have often been used to achieve these industrial computing goals. However, a better way is to use redundant hardware and thin-client software optimized for industrial applications. These products help users scale and locate their automation elements anywhere they want with flexibility and high reliability. This article examines why it is compelling to use thin clients at the industrial edge for improving visualization and control.
Figure 1. Computing power located at the “industrial edge” occupies a critical region for improving operations by efficiently gathering data and providing visualization when and where it is needed, often by using thin clients.
Industrial edge not an isolated case
Visualization and control computing at the industrial edge is applicable and beneficial to almost all operations. Most edge-located systems, devices, and Industrial Internet of Things (IIoT) sensors have become "smarter" and able to provide extensive data. Improved SCADA and HMI connectivity at the field enables access to this data.
Plants and processes can operate more efficiently when more HMI functions are deployed on the production floor, at field locations, or wherever operators need them. This includes basic process monitoring and control, where operators need an immediate real-time picture of production that is accurate and comprehensive, along with the ability to make adjustments and changes. But it also involves providing visibility into more detailed analytics performed on the big data obtained from field devices. Analytics reveal longer-term trends that may not be addressed by directly observing real-time data, but which informed operators can act upon to improve efficiency.
In addition to operational improvements, other stages of the project life cycle can take advantage of the industrial edge. During design and development, proven edge computing architectures are a structure that can be reused from project to project, leading to design efficiency. The modular nature of edge computing means original equipment manufacturers (OEMs) and system integrators (SIs) can do programming and testing development work on an in-house development platform, and then quickly deploy the results to new and existing field production systems. Fast HMI deployments and mobile capabilities make it far easier to commission new systems and to update existing ones.
Ongoing maintenance is simplified by reliable thin-client devices, which are rapidly replaced and redeployed if necessary. As with commissioning, being able to deploy mobile visualization and computing clients on laptops or tablets gives maintenance crews more options for troubleshooting problems.
Who owns industrial edge computing?
At this point, it is relevant to examine who owns the industrial automation computing structure and how that definition concerns industrial edge and thin-client rollouts. Traditional industrial computing solutions have been heavily based on commercial information technology (IT) infrastructure, and rightly so. Many computing technologies used in industrial applications have trickled down from the commercial world, including PCs, servers, Ethernet wired and Wi-Fi networking, virtual machines (VMs), thin clients, and certain redundancy schemes.
However, manufacturing and process industries are built around the always-on world of operational technology (OT). OT requires much of the computing infrastructure described above, but adds mission-specific hardware, software, and communications methods. This includes PLCs, HMIs, smart instrumentation, and industrial Ethernet protocols.
Converging IT and OT business units is not the end game, but industrial edge deployments must successfully coordinate both groups. Generally speaking, IT personnel are not trained to work with industrial-specific products. In fact, the industrial network usually must be carefully firewalled from the business network. OT depends on VMs and thin-client technologies, but personnel are often not equipped to manage extensive IT-centric systems.
A workable middle ground is to package IT-centric hardware and software deployment capabilities into OT-focused platforms. In this way, OT personnel can readily operate and maintain IT technologies.
Thin clients aid the edge and core
Traditional automation computing architectures have included both distributed and centralized elements. Purely OT devices, such as PLCs and PACs, have been installed at the industrial edge to interact with field devices like motors, valves, and sensors for gathering information and performing detailed control. These OT assets continue to become more capable. They still play an important role.
Crossing over into the IT realm, industrial automation SCADA and HMI servers formed a "core" above the OT devices, networked to desktop PCs situated throughout the facility as needed. Although this IT-centric server and PC arrangement is functional, this configuration can be cumbersome to manage, because it is relatively expensive to deploy and maintain numerous remote PCs. And now, the growing trend to install control and visualization computing assets out on the factory floor, or even on skids and machines, makes this an even more complex proposition.
A better solution is to maintain centralized redundant server hardware at the core, but use it to host automation-related VMs, while serving up HMI applications to remote thin clients as needed. The servers can be located in a secure computer room or another protected yet remote location like a control room or electrical room. Redundant servers can be traditional IT-centric style or OT-optimized versions tailored for operating in an industrial role (figure 2).
Figure 2. Purpose-built edge computing platforms, like this Stratus ztC Edge system that operates as a redundant pair of nodes, can withstand challenging environments and are easily deployed and maintained by OT personnel.
Thin-client technology is the preferred way to reliably deploy and manage distributed HMIs and virtual machines throughout a facility, especially those systems supporting mobile device clients. This means any industrial automation VM or application can be viewed and operated at any PC, panel-mounted terminal, or mobile device connected to the company intranet.
This thin-client architecture brings a better experience at the edge and is far more maintainable by OT personnel responsible for the industrial automation core. Some benefits are:
- Inexpensive edge: Edge-located thin clients are lightweight in terms of hardware resource requirements and relatively inexpensive. They can be quickly replaced and reconfigured.
- App-serving flexibility: HMI applications can be served to any sort of remote device, such as a PC, panel-mounted terminal, or even mobile devices.
- Easier development: Factory development and testing activities can be carried out on a VM environment hosted anywhere; actual field-deployed hardware is not required. This ability is very significant for OEMs and SIs.
- Rapid integration: Transferring development configurations to production system thin clients is convenient and quick, especially compared to configuring multiple standalone physical servers and PCs.
- Simplified maintenance: Centralized control of VMs is easier than maintaining widely distributed assets that would otherwise require in-person attention for updates and security patches.
- Scalable: Thin-client architectures are readily scalable and benefit from centralized standardization and reuse.
- Verified: Best practices can be established and maintained across deployed devices, for consistency, reliability, and repeatability.
The preceding benefits are only the basics that standard thin-client configurations provide. Just as the industrial hardware experience can be improved by using OT-optimized servers, so too can the thin-client software experience. Thin-client manager software optimized for industrial users is available (figure 3) and adds the following to enhanced thin-client management:
- Redundancy: VM sessions are redundant and can fail on the server side to keep the thin clients running.
- Shadowing: Administrators or terminals can view and operate another terminal.
- Session control: Multiple sessions can be combined and arranged on a single display.
- Role-based control: Organizations can control and manage the content delivered based on login. Certain users can view and control only what they are authorized to see and change.
- Locational control: Content can be tailored to the location of the thin client.
Next, let's look at the architectural shift that enables thin-client deployment.
Figure 3. Thin-client deployment is eased by mission-specific visualization and mobility software like Rockwell ThinManager, which delivers content to many forms of computing and mobile devices.
Built for operations
Traditional automation computing architectures commonly employ servers and PCs, while the improved configuration advocated here uses servers and thin clients. On the surface this does not seem like such a drastic difference. However, the distinction is where the computing is performed and how redundancy is carried out.
Classic architectures use servers to perform core supervisory computing services (e.g., VMs for SCADA I/O servers, historians), while remote PCs execute HMI functions and access the servers for I/O points. Reliability is based on dependable servers, redundant networks, and multiple parallel PCs. Careful IT configuration could enable high availability and failover between server VMs, but these would be custom configurations.
On the other hand, thin-client architectures centralize almost all computing on the servers, even the HMI functionality. VM sessions and HMI applications are delivered out to thin clients, with each acting as a window into functionality hosted on server VMs. But because the critical computing core is more centralized, it becomes more important to improve network and server redundancy.
As with classic architectures, the server VMs could be hosted on traditional hardware with customized high-availability configurations, but a better option is to use industrial-specific servers with paired redundant nodes. These systems can load share individual VMs between two nodes, or even assign a VM to one node or the other. In the rare event of any single hardware failure, this type of redundancy has zero downtime.
Furthermore, using industrial-grade thin-client manager software installed on these servers provides even greater reliability. OT-optimized servers and thin-client software are complementary products for visualization and control computing services at the industrial edge.
Closer to the edge
The nature of the production and manufacturing industries, with their emphasis on reliability, means they do not usually employ cutting-edge technologies for automation. However, each time industry personnel move ahead on a new project, they are well positioned to survey the technological landscape and make good use of proven technologies. To improve productivity and OEE, end users have recognized a need to enable visualization and control closer to the industrial edge.
SCADA and HMI visualization have been fundamental elements of automation strategies for a long time, but now there are better ways to deploy these systems. Establishing an architecture of redundant servers supporting remote thin clients provides the familiar benefits of SCADA and HMI systems, while allowing them to be easily extended to any location. Content can be delivered to any fixed or mobile device. Thin-client architectures are a modular way for OEMs and SIs to perform development, a rapid way to deploy the work to the field, and a flexible means for operations and maintenance to own and operate these systems for the long haul.
This improved method for visualization and control can be achieved by using customized commercial solutions and carefully coordinating the activities of IT and OT personnel. However, a better approach is to use mission-specific server hardware and thin-client software products optimized for industrial applications-which can be more readily deployed, operated, and maintained by OT personnel.