From black art to mainstream

Putting embedded intelligence into a piece of equipment has traditionally meant either putting a standard programmable logic controller on the equipment or having a system developed just for a manufacturer's needs.

Both solutions have their advantages and disadvantages.The PLC is somewhat inflexible from the functionality and size standpoint but the custom system is usually expensive and can take years to design and implement. Until recently, there has been little in between these two solutions.

But in the last two years software companies have started to view the embedded control arena as an opportunity to combine the flexibility and size of custom systems with the standardisation and development environment that come with a PLC. Pioneered by CJ International with ISAGraf, small software companies have been developing standard tools that follow the IEEE 1131.3 programming language format. CJ International took IEEE 1131.3 and applied it to a wide range of embedded operating systems to create embedded intelligence that rivals a medium-sized PLC.

Many users of these embedded control tools have the fledgling PC-based controls market to thank for this advance. Companies like CJ International, Think&Do, SteepleChase, eMation, Questra, VMIC and Beckhoff developed PC-based control that has migrated to commercial embedded operating systems like Wind River System's VxWorks, and Microsoft's Windows CE. This migration has brought the realisation that users are looking for standardised development tools that load and run with a multitude of operating system and hardware combinations. Once again CJ International led the way by developing target-independent code (TIC) that lets a single developer program machine operation logic with little regard for where it is going to be run. This software developer is freed from having to be a hardware engineer, which brings lower costs and faster development as hardware and software evolve independently and in parallel.

The next step in this evolution requires improvements in operation and better communications between intelligent components. Altersys recently acquired CJ International as a means of helping companies manage and communicate with distributed, intelligent devices. By owning the development environment, Altersys hopes that companies will use its other tools to manage logic code as well as information available within intelligent devices. Web servers embedded within the code generated for the hardware allow other Altersys applications to aggregate data from many distributed pieces of equipment. Think&Do, now called Entivity, has a similar approach is but is currently limited to Windows CE and PC-based platforms. Think&Do also has a development environment based on Microsoft's Visio graphical development environment which is fairly common in industry and makes it attractive when there is a move to get IT departments more involved in control system development.

The web may seem to play only a minor role here, but in reality it is the driving force behind the development of standardised tools for embedded controls. Most equipment manufacturers have not seen the need to embed intelligence in their products, but as more customers demand visibility into machine operations, the need to have information within the controller exposed on the web has been behind the need to embed controls.

Although traditional PLCs have the ability to offer data up to the network they have not been cost effective where a price point of $250 is considered unattractive. On the other hand the cost of developing web functionality within custom embedded controls has also been high and they are difficult to maintain. Because of this, embedded development environments created by companies like Altersys and Entivity have really pushed the web potential of their products which in the end this may lead to the engineer's dream of having all data exposed, all of the time. What was once a black art is now well on its way to becoming standard practice.

Software companies have started to view the embedded control arena as an opportunity to combine the flexibility and size of custom systems with the standardisation and development environment that come with a PLC

• AMR Research
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