Automation Networks: From Pyramid to Pillar

Nov. 2, 2017
As automation technologies advance with cloud and edge computing, system and device location on the network can, in some cases, become optional. Critical to this development will be the greater adoption of standard Ethernet and the use of Time Sensitive Networking to maintain expected levels of control.

Though the Industrial Internet of Things (IIoT) may not be changing industry overnight, it’s clear that many long-familiar approaches and processes are undergoing a transition as a result of IIoT. One of the clearest examples of this is the automation system pyramid. Layering technology from field devices and I/O to controls to MES and SCADA up to ERP, the image depicted in this pyramid graphic has been burned into the brain of anyone involved in the connection of systems from the shop floor to the top floor for more than two decades.

But even this long-familiar illustration is going through changes in the face of IIoT. Its new construct is more of a pillar than a pyramid. The reorientation of this graphic became necessary for two reasons: 1) the need to better highlight and distinguish the networks that connect the layers, and 2) to reflect the fact that some technologies may no longer reside in the facility but in a local or remote cloud computing environment.

Industry’s move to use common Ethernet network technology from the front office to the shop floor allows for data and computation to be located where it makes the most sense, rather than being located in a specific space due to technology constraints. For example, processes that do not require hard, real-time control can now be run in the cloud with virtual PLCs—as shown in the pillar graphic. The graphic also depicts how, with IoT, data can now be shared more easily through all levels rather than sequentially from one layer to the next.

A need to more clearly distinguish the communication aspects of networked devices and systems became important as industry began moving away from a pure reliance on fieldbuses and toward greater use of Ethernet. The development of Time Sensitive Networking (TSN), which brings determinism to standard Ethernet, underscores the importance of this change as shown in the pillar illustration.

While attending the 2017 IoT Solutions World Congress (IoTSWC) in Barcelona, I had the opportunity to speak with Jeff Lund and Oliver Kleineberg of Belden following their presentation on TSN at the event. TSN figures prominently in the work of the Industrial Internet Consortium (IIC), the organizer of the IoTSWC, as it forms the focus of the IIC TSN testbed. This testbed involves some of the biggest players in industrial automation, including Analog Devices, B&R Industrial Automation, Belden/Hirschmann, Bosch Rexroth, Cisco, Intel, Hilscher, KUKA, National Instruments, Pilz, Renesas Electronics, Schneider Electric, Sick, TTTech and Xilinx. The involvement of so many high-profile players underscores the near-term, real-world potential for TSN across industries.

In their presentation at IoTSWC, Lund and Kleineberg spoke about how TSN can begin to be used on networks lacking TSN-capable devices—which will be the case for most industry applications for a number of years.

One way of doing this is to use TSN edge switches to connect end devices to the TSN network. “Of course, determinism will depend on the capabilities of the end device,” said Kleineberg, “But having non-deterministic devices on the network won’t impede the deterministic ones.”

Another approach is to swap out existing protocol masters/controllers with TSN-capable ones. “This approach allows you to keep your end devices as they are,” Kleineberg said. “Using a TSN-capable protocol master/controller, you can port your automation protocols to be transported over TSN. The master synchronizes the protocol schedule with the TSN schedule and allows the automation protocol to be transported seamlessly over TSN. This allows a step-by-step approach to TSN for brownfield plants because they can keep all their existing, protocol-specific devices and just change out the masters. Once that’s done, the devices can be changed out one by one over time. In the meantime, by transporting the automation protocol through TSN, connectivity between old and new devices can be maintained.”

Lund pointed out that, even without having all TSN-capable devices on your network, the plant can still get distinct benefits from having a TSN network in place. Kleineberg explained the reason for this: “Even if the end devices are non-deterministic or not TSN capable, their communications will travel over the TSN network. As the communications from those devices merge onto the TSN network, they will be handled deterministically,” he said.

As exciting as the potential is for TSN, Kleineberg and Lund agree that the technology is currently overhyped. Despite that, both say that real industry interest in it is growing exponentially.

“TSN is currently just a Layer 2 technology; it needs the development of application protocols to advance further,” said Kleineberg. He admits that some pushback against TSN does exist from suppliers that prefer to use proprietary networks. “But the farther those suppliers get away from standard Ethernet, the harder it will be for them,” he said. “End users are very positive about developments like TSN that promise to bring standard networks to the plant floor.”

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