In the competitive world we live in today, it is vital that processes are kept tightly controlled. Problems in any given process must be identified immediately so they can be quickly corrected. Efficiency is vital to maintain and maximise the profitability of any process. In order to achieve this, a highly effective, reliable and robust control system must be deployed. Traditionally PLCs have been the preferred choice, but today from the backbone to the front-end, industrial computers are taking control.

The PLC started out as a replacement for banks of relays. Gradually, various math and logic manipulation functions were added. Today they are the brains of the vast majority of automation, processes and special machines. PLCs now incorporate smaller cases, faster CPUs, networking and various internet technologies. You can think of PLC technology as a small-industrialised computer that has been highly specialised for reliability in the factory environment. At its core, a PLC looks at digital and analogue sensors and switches (inputs), reads its control program, makes mathematical calculations and as a result controls various hardware (outputs) such as valves, lights, relays, servo motors, etc. in a time frame of milliseconds.

While PLCs are very good at quickly controlling automation, they do not share data easily. At best, PLCs would exchange information with operator interfaces (HMI) and Supervisory Control and Data Acquisition (SCADA) software packages on the factory floor. Any data exchange with the Business Level of the company (information services, scheduling, accounting and analysis systems) had to be collected, converted and relayed through a SCADA package.

Most PLCs, typically have a communication network that’s unique to the brand, and limited in speed. With the acceptance of Ethernet, communication network speeds have increased but still often use proprietary protocols.

Overall, PLCs are getting faster, smaller, cheaper and more powerful. As a result, they are gaining capabilities that used to be the exclusive domain of the Personal Computer (PC) and workstation arena. This translates into critical data quickly and cheaply being shared directly between the PLCs on the Factory Floor and the Business Level of the company. This is a far cry from the PLCs of 10 years ago.

Today Industrial computer usage accounts for more than 60% of all automation applications and more than 40% of motion control applications.

24/7-365, day-in day-out, industrial computers perform what are essentially simple logical calculations, at unimaginable speeds.

For the majority of process control and automation applications SCADA systems are deployed. These systems encompass a wide range of communication and data acquisition methods and protocols. An effectively designed modern SCADA system can both control a process and provide pro-active warnings to operatives preventing failures and the process from going out of control. In today’s modern SCADA systems Industrial Ethernet (IE) is being widely adopted. Offering important features such as redundancy and fast ring recovery IE also provides a route to easily integrate the production or automation process with the business Level systems. This allows information to be accessed freely and easily away from the process, potentially anywhere in the world. IE has helped to support the continued increase in the use of Industrial computers in SCADA systems. Industrial computers offer excellent expansion capacity and a huge range of plug in cards for data acquisition, and communications. This means an industrial computer system can be tailored to fit the precise needs of any SCADA system.

Pirelli are a world-wide brand, famous for their high performance tyres. Pirelli’s slogan ‘Power is nothing without Control’ seems apt for their approach to a recent systems upgrade at their UK Central Distribution Hub in Burton-on-Trent, Staffordshire, UK. A fully automated distribution centre, the requirement was to modernise the eight store cranes that pick and place the tyres for distribution. To achieve this Amplicon partnered with system integrator Siamtec who specialise in SCADA systems. To modernise the system, Siamtec replaced all the PLCs on board the cranes with Panel PCs and Industrial bluetooth link. Combined with Siamtec’s SCADA software this enables the cranes to communicate with one another and the central warehouse command and control room. Furthermore, the Panel PC can also act as an HMI (Human Machine Interface) to enable an operator to manually over ride and control a crane.

The boundary between an industrial computer and PLC has become grey. The continued development of industrial computers has made many question their traditional choice for control based applications. You no longer ‘have to use’ a PLC. In fact it is now considered a safer choice for business’ to use an industrial computer because it is an open standard. This means you can select from many, many vendors and not have to commit to just one as you do with a PLC. It’s now possible for industrial computers to function and perform just like a PLC.

With the right components, an industrial computer system can provide everything a PLC has to offer. Selecting the processor boards means you can dictate the physical size. There are many form factors from PC/104 through to SBC/backplane configurations. These allow you to not only determine the size, but also the expansion capacity.

A system can be made fanless and highly powerful using the latest generation of Intel, AMD or VIA low power, high-performance processors. Hard drives can be removed and replaced with solid state flash based storage. A Real Time Operating System (RTOS) enables a industrial computer to be as robust and reliable as a PLC. A wide variety of RTOS’s are available from Linux derivatives through to Microsoft’s XP Embedded and many more such as Green Hills, QNX and Wind River, each having their own particular merits for different control applications.

Industrial Computers also offer the user total programming flexibility. You can decide and select to use either a high level drag and drop visual programming environments or a more traditional programming language such as Visual Basic or C.

More and more people are and have stepped away from PLCs, and are deploying Industrial computers. In fact industrial computers are starting to look and act more like PLCs, making the differentiation even more grey. For example Moxa’s new Universal Communicator UC-7408 provides 16 digital I/O lines 8 serial RS232/422/485 ports and dual LAN. It also comes supplied ready to run with a RTOS Linux derivative on embedded flash storage. An Intel Xscale 266MHz processor and 128MB RAM. This provides adequate power for custom applications. Furthermore the UC-7408 has a CompactFlash socket and PCMICA slot for wireless expansion. This is packaged in a fanless DIN rail or wall mount unit that draws just 8W of power, and comes supplied with a complete software development package. This is ideal for intelligent front-end control and integration in to new and existing SCADA applications.