Michael Barrett, ProSys
Most operating companies lack some of the core competencies for selecting a control platform (DCS, PLC or Hybrid). There are several factors which account for this - an operating company may already be used to what they have at their site(s) and have a good knowledge base on their system, or they may have been loyal to a platform since the days of proprietary systems and not realize that a conversion can be as easy to a different brand as to the same brand of an open system DCS. This can limit their decision to that specific platform domain. This knowledge base is commonly a mixture of good and bad experiences with a particular vendor, the ease or difficulty of their platform, and the level of trust that they have with their sales representative.
We have long since left the proprietary system behind and are living with the Microsoft (MSFT) based systems. Keeping up with the changes in a Commercial Off the Shelf (COTS) based system can be a challenge of its own as MSFT moves through different operating systems (OS) and browser versions. The major industries plan on using these control systems 20+ years before contemplating a complete rip and replacement, and management makes investment decisions based on this kind of long term view. However, the technological factors of these systems can change four to ten times in that 20 year span. Serious factors that need to be considered include new processors, high resolutions screens, mobile devices and not the least of the concerns, the cyber-attack threat.
Operating companies focus on making their product safe, at the lowest cost and with the highest quality, which consumes their time and resources. Making a control system selection every couple of decades does not warrant keeping up-to-date on all of the technological factors, as well as the engineering capabilities of the different architectures of each platform. A smart and efficient approach would be to engage a professional engineering company with a breadth of knowledge in the current control system platforms. A consultant works with multiple systems and knows the pros and cons of each. A knowledgeable consultant can set up a Pugh matrix or another form of selection criteria to quickly move an owner/operator from a list of eight platforms to three or four.
Throughout my 40 years of experience, a live 'bake off' has been one the best ways to compare platforms. You can take a demo drive of each system implemented with the same control configuration. Some of the factors to be considered when choosing a control system are:
- Engineering time involved
- Equipment cost
- Capability to fit your process
- Compatibility with other equipment
If it’s not feasible to do a physical comparison, a comparison can be done by a consultant. This can also take emotional attachment to a platform out of the equation. The most critical success factors would have to be knowing and understanding the processes of the owner/operator and safety considerations. Highly experienced process engineers should be used for this recommendation process.
There is a school of thought that in order to guard against cyber hacking, a new strategy is needed in control systems. That a fresh new non-public software layer is the path to security. Time will tell as a few major operating companies are beginning to explore just how that goal could be achieved.