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Footing slips on ladder logic

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AS NATIONAL Instruments struck upon a technology bigger than even it realises? Perhaps. The company has married its renown LabVIEW Real-Time with its industrial distributed I/O solution, FieldPoint, and come up with FieldPoint 2000.

What makes the latest version of FieldPoint different is that up until now there’s always been a PC in the picture - now there’s no need for a computer to do all the control. This reliance on a network meant you could not really get the determinism or the reliability that you might have wanted because you were relying on Ethernet to stay up.

“These FieldPoint modules embody a convergence of major technology trends: from smaller, more embedded intelligent systems, to the growth of Ethernet on the factory floor, to web-enabled applications and the integration of manufacturing and test, “ according to NI president and CEO, Dr James Truchard.

At NIWeek 2001 Todd Walter, FieldPoint product manager, told PACE that FP-2000 was an Ethernet controller that you could plug, communicate and configure through the Ethernet, but that also incorporated a computer.

“You can take this whole set-up and you can download LabVIEW Real-Time to it and now your program can run embedded, you can actually undo the Ethernet cable,” Walter said.

“It opens up to applications very similar to what PLCs are doing, a new realm of possibilities. We’re not trying to replace the PLC but it opens up FieldPoint to applications it couldn’t reach before.

“The key difference between our product and PLCs is going to be the software, as well as the quality of I/O. Analogue inputs are traceable, you can trace them back to how they were actually calibrated.”

According to the company, systems based on FP-2000 are easy to develop, deploy and maintain because of software configurability and modular, networked hardware. Each of the intelligent nodes can act as an independent component in a networked system and still communicate with a host Windows computer. The modules can be integrated into existing systems via Ethernet, and connect to or communicate with RS-232 serial devices.

NI will shoot for markets that need higher flexibility, more powerful programs the ease of use of LabVIEW, and the quality of modularity offered by FieldPoint I/O.

Dr Mark Trotman, founder and MD of Perth-based Icon Technologies is even more upbeat than NI.

“From where we sit we really do see it has the potential to be quite revolutionary,” Trotman told PACE.

Trotman says it is the product that has the potential to thrust LabVIEW Real-Time into the automation and measurementation world, the same way that LabVIEW brought NI into the PC world.

“To my knowledge, it would appear to be quite a unique kind of product in the sense that the FP-2000 has embedded real time operating system, so it’s a PLC. It’s got a very rich and growing vein on I/O, so it would have, today, the same if not more I/O flexibility than any standard PLC. It’s got the same robustness and reliability of any PLC, but it’s LabVIEW programmable, not ladder logic programmable.

“Ladder logic has the great advantage that it is relatively simple to pick up. But it is limited, it’s good for ‘if A, do B’ but once it starts to be ‘if A and C, and a little bit of D, do F or G or H’, it starts to break down.

“That’s the difference, with LabVIEW you’ve got the programmability, which is almost unlimited. You have everything you can program in LabVIEW, with all its ease of use, put down inside a PLC,” he said.

“The hardware architecture is the same as earlier versions of FieldPoint - a network module with extendable I/O modules, it had all the programming flexibility, but it depended on a live link to a PC, so it was not guaranteed real time deterministic, which may or not have been an issue. FP-2000 is real time deterministic.

“It goes beyond the capability of ladder logic. Anywhere where in past you would use a PLC can now use FP-2000, but straight away you have a much richer software programming environment,” Trotman said.

Ladder logic

“It’s a very extreme statement, but you could say it’s potentially the end of ladder logic. Not that ladder logic will disappear overnight, you’ll have ladder logic in 10-15 year’s time, but you can achieve the level of stand-alone reliability and robustness, ‘real time-ness’, at an equivalent price to the old ladder logic PLC.

“FP-2000 can do smart PLC jobs, but much cheaper. It gets around the limitations in very harsh environments where you have had very simple systems that cannot by their nature be very smart: they are cheap and rugged or they have sufficient programming power to be smart and useful, but they are significantly higher in price to overcome the lack of robustness of the PC.

As Trotman points out there is a huge installed base of PLCs that are now 10-15-years-old, commissioned before potential for more complex I/O came along.

“Ten to 15 years ago, all that people would have been thinking of automating in a plant would have been some simple digital I/Os and simple analogue I/Os. The idea that the video might have been an important data stream or that cycle scan rates greater than a few scans per second might be useful, or that you might want data at acoustic rates for vibration wasn’t part of the same domain; now is,” Trotman said.

“For a lot of those people, they’re in a different domain now. Now they may want to do other things. They may want to bring things into their measurement domain that don’t fit into the conventional PLC world, things that are going to benefit from this rich programming environment that is compiled code - you can interact with other systems in the plant directly at the compiled code level.”

Canadian integrator and NI partner, not a company that deals in machine controls, had a company ask whether could build a machine controller, a sheer cutter for metal sheeting.

Could do that with FP-2000 technology, because it had the real-time response they needed for the cutting - been looking for a replacement controller for two years. Company wanted it connected to the CAD system, wanted to take information directly from CAD to control cutting and to log data, ordering information, into our Oracle database. Client wanted much more than a machine controller.

“That’s why I think FP-2000 is really revolutionary because it brings people from one measurement domain into another measurement domain that’s potentially more complex, and potentially much more useful because it can bring all this complexity together with the same embedded reliability.

“There are various schemes that arguably allow you to create enterprise-wide systems, but if you look at most of them at the boundaries between the different types of systems they’re often very primitive: a limited amount of data comes out of this system, is saved, the file is picked up by the other system; that’s not really a very sophisticated way of transferring data today,” Trotman said.

“If you had an environment that can run fully flexible compiled code that can interact with other environments at that level you’ve got a much richer interface between environments in terms of the amount of data that can be moved through in a certain amount of time or the complexity of the data, or both.”

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