Process and IT get together

Global demand for Ethernet IP systems is generating market growth of over 30%, with the fastest adoption rates in Europe, according to Paul Brooks, Rockwell Automation's product manager for networks in the Europe, Middle East and Africa region.

Ethernet IP is enabling process operators to achieve major reductions in costs and cost of ownership, Brooks said, in a presentation at Rockwell's Automation Days event in Birmingham, 21-22 March. These savings are going to become even more substantial going forward, he forecast

The highest uptake rates for Ethernet IP are in three process areas: Food; Infrastructure, particularly water/ wastewater; and 'Skid OEMs', said Brooks.

Food customers are attracted by the combination of EtherNet/IP and HART; common control system architecture between process areas and discrete areas. Infrastructure customers are attracted by flexible topologies, while Skid OEMs are attracted by faster control system design, simplified network architectures and reduced commissioning time.

Networking architectures using conventional fieldbus systems are, meanwhile, being widely used to reduce the cost of cabling, installation and commissioning. They also deliver savings around better information from devices, making it easier to reconfigure them for faster switchovers and facilitating more proactive maintenance.

Over the next five years, Brooks believes that trends in the IT industry, such as the convergence of once separate networks for printers, faxes, phones and video cameras into a single network will also come in to play in the process sector.

"It wasn't that there was anything wrong with those individual [IT] networks, it was just that there were too many of them and too much cost associated with the infrastructure," Brooks commented. "What we need to do in the automation world is to look at that convergence and ask if we can have some of those savings and benefits from these techniques."

On today's factory floor there is still a lot of duplication of time and effort, for example with information networks that are not part of the same management or maintenance procedures, continued Brooks. There is often further duplication with many semi-proprietary fieldbus networks, which cannot be managed by the same tools, procedures or people.

By integrating these various networks within one working architecture "all of the networking devices and information sources on the plant floor can co-exist and work together harmoniously.

"For users, the network becomes transparent and irrelevant, just a like pipe, so all the time they used to spend thinking about the network, designing the network, etc, can be used for something more useful. This makes for better decision-making, better quality, better production," said the Rockwell expert.

To achieve these benefits, however, Ethernet IP has to solve many technical issues and offer all the appropriate features for the factory floor — motion control applications, safety and real-time control among them.

Brooks believes that it now is possible to meet all of these requirements with standard unmodified Ethernet, which he described as a mainstream technology with many hundreds of components available for sale.

Much of the uptake of Ethernet in the process industry is linked to the combination of EtherNet/IP and HART, rather than EtherNet/IP in its own right, he further commented.


Security complex
"This is an industry that remains cautious in its adoption of any networked technology," said Brooks. "The vast majority of instruments currently being sold have HART as their intelligent interface and deliver their primary value through the 4-20mA channel."

Security is another concern and is obviously affecting network purchasing decisions, primarily where end-users are driving a detailed purchasing specification.

Here, Brooks warned against any fast-fix approach: "If a supplier comes to you with a black box that they say solves your security problem, has all you need to be secure and all you need to do is to plug this box into your control system at your factory, then I'm afraid that that supplier is stupid."

Security is a complex problem and it requires many layers of solutions, Brooks continued. "You need to put many things in place because each of them requires different solutions and getting through one means you have still got another five problems to solve rather than the same problem to solve five times."

Ethernet IP, meanwhile, has two limitations; it cannot be used in hazardous areas and you cannot power an instrument from an Ethernet cable, as the automation industry does not accept the power standards that are in place with standard Ethernet. The latter issue means process instrumentation cannot be directly linked to Ethernet IP.

While these issues will be resolved, but "not soon," Brooks added that Rockwell is working to make Ethernet IP, "integrate very tightly with and appear as a seamless entity with all of the process networks, with Foundation Fieldbus, with Hart and with Profibus PA."

Wireless Ethernet has moved forward in the last three years, but wired Ethernet has moved ahead just as far and even further, stated Brooks. "The question isn't how far behind it is, but rather what problems can you solve?"

With control applications, you have to think about the compromises you are prepared to take. Variations of a few hundred milliseconds for a motion control application makes [wireless] impossible, but are pretty irrelevant for a temperature loop in a tank.

"If you are prepared to compromise in terms of the performance you expect from your standard control system there are actually many applications that today we can solve with standard unmodified wireless Ethernet."

Big networks
Brooks said operators really value "managed switches" that enable them to segment big networks through IP subnets or through virtual local area networks (LANs): "Virtual LANs give the ability to segment your network so while you have a single network, the view that you have is actually of many small networks."

Ethernet IP is being deployed on the factory floor in two types of architectures. "The first one is small control system architecture. Increasingly, machine companies who have got a single machine with a single controller, three or four drives, three or four I/O modules, a couple of visualisation stations are adopting Ethernet because it is the easiest network technology to drop into a single machine," said Brooks.

Bigger systems, however, require much more complex architectures. The current biggest is a General Motors bodyshop in the US with 3,400 Ethernet IP nodes on a single network. The biggest current network in the brewing industry is 628 nodes and there is an example with 500 nodes in the printing industry.

By allowing these big networks, Ethernet IP delivers many "new opportunities but also a whole load of new problems in terms of how you design your network, how you segment it and make it manageable," Brooks pointed out.

He went on to describe how Ethernet IP could be applied differently in the different areas of a typical process plant. The challenge lies in understanding the requirements, specifications and network flows needed to meet those requirements ahead of writing a topology (see below) for the application.

In a brewery, for example, a ring topology is often the best for the brewing area, a line topolology better for the filling lines, and star and tree topologies more popular in the packaging area, said Brooks.

Operators, he said, also have to decide on how many nodes and what type of nodes to use on the network. "How critical are these nodes to process safety; what kind of traffic will be on the network; what are the performance requirements; how much data; how fast; and what about availability?"


Cisco: 'Mind the gap'
Cisco and Rockwell are working together to develop reference architectures for a range of process industries including the oil & gas, brewing, and paint sectors, said Arjen Swaag of Cisco.

Installing reference architectures is an attractive solution as, "then you have to do just a little bit of tuning and tweaking and implement it and its gone already 200 times," Swaag said in joint presentation with Paul Brooks at the Rockwell Automation Days event in Birmingham.

"Architectures reduce costs and mean fewer decisions, so you can go faster to market with your new ideas and your changes," said Swaag. "We have built architectures like this for the finance industry, we have built them for all kinds of industries and we can take them more or less out of the box and that's it."

Swaag warned, however, that IT people and automation people and production people need to agree upon architecture before proceeding. "I have been in many, many situations where production people and IT people are not the closest friends. We have to bridge that gap."



Topology options

1) Star: typically implemented with a small machine where you have got a single central switch and all the devices connected to it

2) Tree: a number of switches interconnected in a hierarchical format; switches are connected to higher level switches; high availability architectures

3) Ring: tolerance against any point of failure as comms can reroute around the ring; popular in the automation space

4) Bus/Line: connect from device to device to device; popular as lowest cost of installation for many applications