Open Process Automation: Open Controllers and Decoupling Field I/O

Summary

The Open Process Automation Forum™ standard discussions at the 28th Annual ARC Industry Leadership conference in Orlando in February 2024 both provided information and triggered questions about rising issues.

Fundamentally, the O-PAS™ Standard, a standard of The Open Group strives to leverage technology to achieve multivendor interoperable systems that increase capabilities at a lower cost than DCS offerings.

Important discussions at ARC involved whether we should leverage commercial off-the-shelf technologies (COTS) or create ones; the “We are different” trap; decoupling control comput & field I/O; and more

Broaden frame of reference

I believe the Open Process Automation Forum’s desire for open system is on the right track, but my observation based on presentations is that process industry users creating the standard have a narrow frame of reference because they primarily possess DCS (Distributed Control System) experience. Therefore, their main frame of reference involves closed architecture DCS controllers and I/O, which costs significantly more than PLC solutions meeting the same specifications. Further, the majority of Open Process Automation Forum members are from outside the industrial controls and automation industry, so it would be beneficial to add a more diverse group of users. Today, O-PAS industry members are made up of 18% DCS users, 10% industrial control & automation suppliers, and the balance outside of the broader industrial controls and automation users, mainly IT.

The Open Process Automation Forum brings a level of new thinking, particularly from the IT world, since the initiative is part of The Open Group, which has been focused on interoperable standards since its creation in the 1990s, providing certification for products and best practices, including POSIX and UNIX operating system.

Control edge computing and I/O decoupling now off the shelf

DCS technologies, designs and architecture have lagged the PLC industry where decoupling I/O from Control Edge Computing is already being applied in many control and automation applications today using open industrial networks, industrial computers running control software (i.e. IEC 61131-3) analytics, optimization and other functions that is a scalable computing resource (memory, disk, CPU cores) and open industrial networked I/O.

Industrial computers leverage existing Commercial Off-the-shelf Technology (COTS), applying these devices in a wide range of non-industrial applications at much lower prices than that of industrial controllers. Off-the-shelf Industrial Network rack, slice and IP67 I/O connects to open industrial networks (i.e. EtherNet/IP, PROFINET; EtherCAT) at a significantly lower cost than DCS I/O. 



Open architecture available today provides a great range of configuration flexibility, connecting networked I/O directly to an Industrial Edge Computer for demanding applications or connecting networked I/O to an open shared control and automation network. Ethernet has become the common communications method with multiple Open Industrial Network protocols running simultaneously on a single network.

Considering the longevity of field devices (sensors, actuators, etc.) and off-the-shelf Industrial Network rack, slice and IP67 I/O connected to open industrial networks (i.e. EtherNet/IP, PROFINET, EtherCAT), this facilitates a major Open Process Automation Forum goal. A growing number of smart field I/O devices communicate directly to industrial computers and enterprise consistent with the NAMUR Open Architecture (NOA) model.

The 2023 ARC Orlando Forum showcased several great examples:

• Procter & Gamble's Jeff Kent Discusses AI and Machine Learning
• Digitalizing Manufacturing: 27th Annual ARC 2023 Industry Forum in Orlando
• Remote Multivendor Digital Packaging Machine Services - 27th Annual ARC Industry Forum

The O-PAS Connectivity Framework (OCF) for communications includes leveraging OPC UA, Redfish and associated protocols that can be implemented in today’s configurations described above.

O-PAS™ Architecture

The O-PAS™ Standard defines a system architecture similar to what can be accomplished today but with some new elements.

Distributed Control Node (DCN)

The DCN, Distributed Control Node, is an edge computing device for control including analytics, optimization and other functions that is a scalable computing resources (memory, disk, CPU cores).

The wide range of off-the-shelf industrial computers today can certainly be used to deliver this architecture using the O-PAS Connectivity Framework (OCF) for communications that includes leveraging OPC UA, Redfish, and associated protocols.

'We are different' trap

The Open Process Automation Forum standard that’s under development continues to reference open industrial control and automation standards, Comments about the need to develop new standards in the O-PAS specification rather than cooperate and co-develop with existing standards is a red flag for me. This is a phenomenon I’ve seen in many standards groups: rather than cooperating with existing standard framework/architectures, they want to create their own. 

Unique data models

For example, in the Thursday Open Process Automation forum roundtable discussion, Dave DeBari of ExxonMobil made a comment that OPC UA is, “not as common in industry,” describing how OPAF requires the definition of unique data models in the standard that can be common to all users. However, this is better accomplished by collaborating with the OPC Foundation to create companion specifications. Many other organizations are collaborating to create OPC UA companion specifications and domain specific information models.

Further, these models are now shared on open platforms, including from CESMII (and VDMA, meaning people building applications can easily access and download the latest versions). People building applications simply access cloud repositories and download the latest data models and companion plug-ins for their control & automation project.

Why create new hardware form factor and BUS Standard, InterEdge?

InterEdge originated as part of the O-PAF Standard from the Open Process Automation Forum (OPAF), which is part of The Open Group.

I’m surprised and disappointed that the Open Process Automation Forum has collaborated to create the InterEdge standard, a totally new industrial computer architecture rather than working with other established open standards. For example, they could have used Compact PCI or VME computer bus standards. InterEdge is intended for broad process industry use as an alternative to Industrial PCs (IPC), Programmable Logic Controllers (PLC), Distributed Control Systems (DCS) and their associated I/O modules.

Challenge: Creating a new hardware standard seems counterproductive to achieving the Open Process Automation Forum goals of leveraging open technologies.InterEdge requires traditional DCS and new suppliers to make a return-on-investment decision to design and manufacture InterEdge products to serve a relatively small market niche. Also, the growth of distributed and smart I/O remains an important deciding factor of any ROI go/no-go business decision to produce this new unique hardware offering. Further, leveraging established open bus standards makes a non-traditional vendors investment decision to supply the process control industry more likely.

InterEdge Details

O-PAS has been working with the PICMG organization to define a new standard computer bus and physical card form factor. Dave DeBari explained the goal of hardware interchangeability; working with Georgia Tech and PICMG, he created a draft specification for new open computer hardware bus standard for industrial control. The PICMG now has the ratified InterEdge standard defining an open modular architecture for process control systems (PCS). It consists of Compute Modules, Switch Modules, I/O Modules, Power Supply Modules and their associated interconnecting bus communication protocols and data models. InterEdge Modules are interconnected through data and power buses connected on a passive backplane:

• Compute Module Data Bus (CMDB): A dual 1000BASE-KX network connecting Compute Modules to the PCS control network, with a System Management Network layered on top for management functionality.
• Compute Module Power Bus (CMPB): Distributes power to Compute Modules.
• I/O Module Data Bus (IOMDB): Connects Compute Modules to I/O Modules, consisting of a primary dual CAN FD bus and a secondary, reserved dual single-pair Ethernet bus.
• I/O Module Power Bus (IOMPB): Distributes power to I/O Modules.
• I/O Module Termination Assembly (TA) Interface: Standardizes field signal interfaces at the I/O Module backplane connector.

DCN Hardware Schneider Electric

Schneider Electric announced the release and manufacture of a Distributed Control Node (DCN) based on the INTEL OPA reference design. When I asked Intel, they informed me the Intel reference design is not a full match with the PICMG InterEdge standard. Specifications are not currently available for the Schneider Electric DCN.

Questions, thoughts and observations

When will systems based on the Open Process Automation Forum standard be a sensible investment for mainstream process companies? It is hard to tell how close or far away O-PAS is from the tipping point of success or failure.

Unlike many of the other areas of industrial controls & automation, DCS users have not had open alternatives, and this created the level of dissatisfaction that has led to creation of The Process Automation Forum.
The O-PAS test beds are important to test and validate concepts, hardware, software and system integration. This has value if results and findings are shared and published publicly.

Timing is everything in technology, andmany emerging standards and developments are providing great benefits, including the plug-and-play VDI/VDE/NAMUR 2658 Module Type Package (MTP) standard, Ethernet-APL (Advanced Physical Layer), and OPC UA FX the first open plug-and-play multivendor field device standard. The Open Process Automation Forum needs to keep an open mind and avoid the “we are different” trap, a phenomenon I’ve seen in many standards groups over the years that is counterproductive.