Between a rock and a hard place

The process industry has seen significant advances in control and instrumentation since the days of mechanical field devices.

It's been many years since springs and thermal expansion were used to represent pressure and temperature measurements. More recently, the distributed control system (DCS) and programable logic controller (PLC) worlds that were once so clearly separated have merged to form new hybrid control systems to satisfy the plant manager's pursuit of lower plant costs and increased product quality.

The hybrid control system has heralded a change in control and instrumentation architecture, but what does the future hold?

PLCs evolved from simple on/off control in factory automation applications, monitoring and controlling coils and relays in manufacturing plants, while the DCS has evolved from the continuous process industry, which demanded greater analogue control, diagnostics and higher integrity. The hybrid systems seem a natural progression for the process world, offering the benefits of a DCS with advanced control, greater integrity and single point configuration together with the discrete and sequence control capability of PLC architecture at a more affordable price.

Competition widens

DCS companies now compete not only with other DCS companies but, with the introduction of hybrid controllers, they can also attack applications that were historically more of the domain of the PLC systems.

Conversely, the PLC companies have seen an opportunity to compete with some DCS applications, developing systems such as Siemens PCS7 and Rockwell Process Logix. Few would suggest that either Siemens or Rockwell have taken significant market share from the classic DCS suppliers - but why is this?

A DCS offers a high integrity, high availability system that is tailored to their process needs and comes with the sort of domain experience and support that a multi-million dollar contract would attract. However, to be able to offer this service and overall product requires a DCS organisation that not only has hardware R&D and manufacturing overheads, but also includes software developers, application specialists, systems integration capability, project management and IT specialists for ERP integration. This support must be paid for somehow.

The PLC companies, who are dominant in the factory automation and building management markets, have developed products that suit those needs but must convince process users that they can handle DCS-style projects. This has not been easy. PLC systems that bolt together combinations of HMIs, redundancy, and function block capability aren't quite at the level that the DCS suppliers offer, and they are only just entering the market with some limited HART and fieldbus capability.

Secondly, there are support issues. Major PLC companies have either developed or bought-in integration facilities to give the organisation the in-house credibility for the process market. However, like the bolt-on nature of PLCs, this bolt-on integration capability is not convincing enough process customers.

While these issues are important, the problem may be deeper than this. The main issue is business culture. DCS and PLC companies tend to be based around very different business models, and the competition between the two groups is beginning to show up that cultural difference.

PLC companies make their money from shipping volume boxes of (mainly) hardware through all sorts of different channels, including catalogue sales. Control hardware represents up to 75 per cent of the turnover of the typical PLC outlet. This is the basis of their business culture and all their internal language - but it is not the shape of company that a process user expects.

The DCS sales person probably won't ever show the customer 'dull' hardware, but will demonstrate the process experience, support and IT capability of their offering, which will save money from plant efficiencies and debottlenecking. They only make an equivalent 35 per cent of their turnover in hardware, with the remainder made up of application software, support, training, licence fees, project management and service contracts.

Ironically, with the senior management push to shape their organisations to attract process customers, the PLC companies are taking on extra overheads to match the other DCS offerings. The PLC companies will (if they are to be successful), move towards the very thing that is crippling the DCS companies today - high fixed costs, making the product overheads high.

Operator dilemma

Today the process end user is caught between the higher cost DCS offering (the rock) which may preclude the project approval, and the 'sticking plaster' PLC solution that struggles to meet the needs for the process plant (the hard place).This is the real market dynamic, and the real driver behind the request for more openness in the process market.

Process end users want the best of both worlds. They would like to be able to select process control components that offer true process control capability for the smart analogue control together with the logic controllers for more sequential operations. They want the high integrity, redundancy, HART and fieldbus capability that is offered by the DCS, but the openness and lower costs of the PLC world. In short, they want the hybrid style functionality but with the PLC price and accessibility.

Best of breed

To meet this need, companies are evolving to allow the process end user to select their 'best of breed' hardware and software components. These can be connected to other producers' open components, allowing them to be snapped together to create sophisticated control solutions tailored to their process needs. This will allow them to drive costs down even further.

These changes in the process control market are similar to those in the computer industry in the 1970s. Larger companies such as IBM, Wang and DEC, who produced proprietary systems, were dislodged from their market leading positions by new upstart companies such as Compaq, Dell, and Microsoft, which developed open hardware and software based around the PC. Today, the Sony PC user can connect to a Hewlett Packard printer, while viewing the data on a Dell VDU. This has forced down the prices of hardware and encouraged faster product innovations between manufacturers.

As these changes occur within the process control world, it is likely that the larger control companies will gradually move away from the supply of hardware and 'shrink-wrapped' software and focus more on application engineering and system integration.

The $8billion-plus market is attractive for the PLC companies, but to compete with the established DCS players, they must not only continue to improve their current product offerings, including the integration capability, but they also need to engineer a significant culture change throughout their organisation.

The emergence of open control components offers the process user a new option by ensuring that they can use products designed for their specific process applications but only pay for the features and services that they actually use.

New era

This vision of the process market can only be achieved by using industry standards and de facto protocols and we are beginning to see some consolidation with the dominance of a few field level and high-speed buses together with the acceptance of Ethernet as a plant wide vehicle.

Open components for the process industry are here and they are changing rules for selecting process solutions. The new age of process control is upon us now.

Mark Jacobs is regional sales director for MTL Open System Technologies.