Migrate your hard coded batching system

Prior to the development and acceptance of ISA-88 batch standards, legacy-batching system required the entire recipe, or procedure, to be hard coded directly into the controller. Today those end-users are faced with the inevitable task of migrating the inflexible legacy platforms to a modern control system.

By Robbie Peoples, Cross Company Integrated Systems Group August 18, 2014

Prior to the development and acceptance of ISA-88 batch standards, legacy-batching system required the entire recipe, or procedure, to be hard coded directly into the controller. Essentially, this meant that the procedural level was not isolated from the equipment level. Today those end-users are faced with the inevitable task of migrating the inflexible legacy platforms to a modern control system.

Thankfully, the enhancement of technologies and acceptance of control standards have allowed for the modern day control system to become more robust, flexible, and easier to configure. This software provides an ISA-88 structure to separate the equipment functions from the procedural, or recipe, layer. My purpose is to clarify the benefits of batching software and flexible design during a legacy batching system migration.

Hard coded legacy batching systems tend to have a lot of custom code to handle all of the exceptions, automated logic, and operator interactions during processing. Typically, the actual code for the process sequencing is fairly straight forward, and can easily be defined by the local process engineers. Alternatively, the most complicated logic within a batch typically revolves around exception handling and automated logic. This logic can represent up to 60% more coding infrastructure than the base sequencing logic.

In addition, most legacy system are a blend of automatic controls coupled with manual operator interactions. All of the considerations add to the base controller logic, which makes the code overly complicated, cumbersome to navigate, and difficult to change.

In most cases, the engineer maintaining the system is not to same person who actually coded the logic. Also, the project manager charged with replacing the existing legacy control system may not be familiar with the new methodologies and system enhancements that ISA-88 can provide. Therefore, the situation often necessitates a full understanding of the benefits when evaluating the options.

Hard coded batching systems typically have common characteristics that can be improved by using a flexible ISA-88 design coupled with a good continuous improvement program. If you can answer "Yes" to any of the following questions listed below, it may be beneficial for you to consider using batching software:

  1. Does the process require a control system engineer to support production on a continual basis?
  2. Does production have quality issues, or produce a product that is off spec sporadically and without reason?
  3. Do you have variable production cycle times when producing the same product?
  4. Does changing products and/or tweaking specifications require a control system engineer to support?
  5. Do you have personnel dedicated to gathering, collecting, and producing production data for analysis by management?
  6. Does implementing new equipment require an extensive amount of time and effort? 
  7. Do you feel that you have reached the maximum efficiency with the given system?

Full Batching vs Hard Coding

To define the pros and cons of a full batching system versus hard coding the recipe directly into the controller, we have to provide some understanding of ISA-88 and how the standard helps us. The big question is, "How does the implementation using ISA-88 standards translate into business benefits?"

Just like anything else, if you do not utilize the tools and enhancements correctly, it is difficult to show a Return-On-Investment when implementing a cost benefit analysis. Meaning, a poorly designed system can still follow ISA-88, but it may not be flexible and robust enough to provide a long term benefit. The outstanding question: "to batch or not too batch" is more of a business decision than a process decision. In addition, the approach to control system migration should prioritize the long-term costs — or more well known as the life-cycle costs — over the initial project costs.

The sections below highlight the key areas of improvement, but the overall benefits can have a ripple effect and provide a vast amount of return across multiple sectors of your business!

Having Standards… Reduces Confusion

Configuration standards emphasize good practices, and that in itself has long-term value when implementing continuous improvement projects. The concept of using standards can be applied to using a keyboard on your PC. What if every PC that you ever used had a different keyboard arrangement? That would cause you a lot of wasted time to find each key, and ultimately it would hinder your performance on a daily basis. Thankfully, someone identified the QWERTY standard key set, and now using a keyboard is universal and understood by all.

Likewise, configuration standards outline common functions and methods of interaction that are repeatedly used to accomplish associated tasks. The familiarity simplifies the interactions between the functions and ultimately leads to more easily identifiable functions.

Reduces Development Cost and Time-To-Market

Implementing the ISA-88 standard reduces the cost of developing or augmenting a product, and ultimately reduces the time-to-market. The standard promotes the reuse of functions because they are broken down into smaller parts that are more common between different pieces of equipment. Any world-class control system integrator will have established libraries that are used to implement projects, which have been tested over time. These practices lead to a quick development and deployment, which ultimately lowers the overall cost of delivery.

A robust standard can also minimize downtime by providing operators and maintenance personnel with valuable information to quickly identify equipment issues. The reuse of standard functions provides less risk, and reduces the validation and commissioning effort as well.

Reduces Maintenance

Following the ISA-88 standard will result in an easier system to maintain. The standards breakdown of complex functions into smaller pieces will allow them to be managed on a smaller and simpler level. Making additions or modifying smaller sections of the code will result in less risk than making major, more involved changes. These benefits are applicable to both fully automated systems as well as those with manual operator intervention. When a standard is properly applied to a system, the amount of time required to support continuous improvement projects is minimal when compared to hard coded batch systems.

One of the long-term benefits is the increased control system engineer efficiency. This efficiency allows the systems engineer to spend his time working on OTHER items to support the process instead of troubleshooting and deciphering custom coded solutions. In addition, recipe changes and/or new recipe development can be implemented by process engineers that understand the process, but typically do not have a controls background to decipher the logic in the control system.

S88 accomplishes this by separating the equipment layer from the recipe or procedure layer, allowing the process engineers to develop and change recipes as needed without having to understand the equipment code in detail.

Reduces Life-Cycle Cost

All of these benefits listed above contribute to reducing the life-cycle costs of a system. Analyzing the costs associated with developing, maintaining, and implementing continuous improvement projects has made upper management realize that the long term benefits far exceed the short term cost savings. This decision to utilize batching software, coupled with a flexible design, allows companies to quickly adapt to the market place with minimal costs when compared to having to reconfigure a recipe hard coded in the controller. Most organizations for whom I have provided support have utilized the benefits of batching software… and that decision was made at the top management levels.

In several cases, I have had the local process engineers tell me that the current system has been tweaked over the years by good engineers, and that they have reached the maximum efficiency. After implementing a new batching system, both of these cases have established new record levels of production and quality within a year of installation. These results are directly contributed to the advancement in technology making better tools to increase efficiency. The companies that embrace change and push the use of technology advancements to ensure continuous improvements tend to survive the long haul.

This type of forethought is what keeps companies moving forward and competing on a global market.

Batching Software Will Help You

In summary, implementing the ISA88 standard using a flexible and robust approach can help reduce the implementation costs, as well as the life-cycle costs. One of the most under-estimated benefits of using configuration standards are the costs associated with maintaining a system. Operating in a global market, we must be cognizant of our efficiency, and take advantage of every opportunity to continuously improve our processes.

The decision to utilize batching software is a business decision rather than a process decision. The forethought of the long-term improvements must be led by managers to ensure our companies’ success for long term employment. This fact holds true for a fully automated process as well as a blend of manual and automatic operations, which is encompasses most of the batching processes today.

Embracing change and the use of new tools is our responsibility to ensure that the next generation is setup for success. If you have any comments or questions about this topic, I’d love to hear them! Feel free to email me, or comment below.

Robbie People is a Project Manager & Lead Systems Engineer at Cross Company Integrated Systems Group. Innovative Controls is an elite process control systems integrator based out of Knoxville, TN. Robbie has over 17 years of experience in the process control industry, specifically in the chemical and pharmaceutical industries. He holds a Bachelor’s Degree in Electrical Engineering and is a registered professional engineer, in the discipline of controls systems, in the states of Georgia and Texas.

Cross Company Integrated Systems Group is a CSIA member as of 3/5/2015