Board Level Controllers – Best of Both Worlds

Submitted by Nathan Ehresman || Valin Corporation
An operator in a fluid handling process is only as effective as his ability to work with a given controller. If there are factors that keep this individual from doing what is necessary for a smooth operation, adjustments need to be made. Usability and programmability are two of the more important factors when determining which controller best fits the needs of the process.  However, there’s no way around the fact that cost plays a predominant role in the decision as well.

Discrete PIDs

Most control panels designed for fluid handling applications use a discrete PID controller.  These are very common in the industry mostly due to their profound versatility. Discrete PID controllers can handle a variety of inputs and use a built-in, robust algorithm. This allows the controllers to handle a multitude of unique variables and conditions.  Furthermore, discrete PID controllers contain many useful outputs. These types of controllers are designed to be able to handle the majority of I/O that an operator typically needs for an industrial process, with a low amount of variability. Eliminating as much variability in the process outcome is critical, as variability oftentimes equates to scrap, which in turn reduces profit.

These controllers, while versatile, do not provide for a good customer experience.  In order to program them, the customer must navigate a series of draconian menus. Anyone who has spent some time with the menus inherent to a typical discrete PID controller can tell you what a frustrating experience it can be. The operator needs to be able to set values for proportional, integral and derivative functions, as well as process set points, alarm trigger points, and the type of alarm required. It can be incredibly time consuming, frustrating, and easy to get wrong, which would cause the controller to function at a less than optimal setting, leading to increased scrap. Furthermore, the display is not in plain English. The display may show text such as “OUT” or “OPT” and the operator will need to know that this stands for output.  Then he or she must toggle through and find the proper output desired.

As a society in general, people are used to accomplishing these types of programming tasks easily. Most are now used to search engines which display results in English.  These types of controllers aren’t exactly “user friendly.” To complicate the issue, with the retirement of baby boomers, the number of engineers that know their way around these types of controllers have been dwindling. It is more difficult to find individuals that are part of the “new generation” that can effectively navigate these systems.

Manufacturers have tried to combat this by creating downloadable software and equipping the controllers with USB ports. Before, an operator would be required to interface with a 4x4 square with buttons and a tiny display. Now, with the software, users can interface on a computer screen with their laptops. With this approach, an operator can open an interface and easily set PID values, alarm functionality, input/output ranges, etc. It became a much more pleasant interface and experience. This approach can also save an incredible amount of downtime. The last thing a company wants when one of the controllers goes out is to see their technicians working on these pieces of equipment with an owner’s manual in their hand, trying to get the controller to work again.

Unfortunately, many large end users have restrictive IT policies that don’t allow for manufacturers software to be installed. So, this option isn’t always a viable solution.


Accutrace Heat Trace Controller
PLC’s are another option as they can offer a far better user experience. They have larger screens and contain an integrative software that ultimately delivers a better translation than the discrete PID controllers. However, they are expensive and lock the customer into service and licensing agreements. 

The programming, while easier than with discrete PID controllers, is also typically far more complex than the simple control loops required by most customer applications. Imagine taking a sledgehammer to pound a nail into a wall. The amount of power the PLCs can muster is sometimes greater than it needs to be, thus the heavy price tag. PLCs are most typically used in applications such as linear motion, robotics, and others involving advanced math algorithms.

The Board Level Controller

Most fluid handling applications would greatly benefit from an option that is more user friendly than the discrete PIDs (without being limited by IT restrictions) and less expensive and powerful than the PLCs. This “best of both worlds” approach is achieved by using a board level controller as the “brains” of the panel and an HMI with a pleasing and intuitive interface. The HMI is fully customizable and is incredibly easy to use, thus providing a superior customer experience. The HMI is set to display plain English, and utilizes a touchscreen with a more intuitive, understandable interface. It is particularly desired by the younger generation in the industry.

The board controls combine the punch and computing power of a traditional PID controller with the aggressive price point offered by bulk purchases of mass-produced circuit boards. Particularly ideal for any thermal process containing a thermal couple and a heater where the operator needs to maintain a certain temperature, board controls are continuing to grow in popularity. With applications such as heat trace, process heat, or superheaters, the board level control allow operators to do what they do best as opposed to getting frustrated with the complex programming and troubleshooting that comes with an alternative.

Article published in Flow Control Magazine
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