At its core, a manufacturing execution system (MES) is used for managing and monitoring work-in-progress activities and data for a manufacturing process. With particular emphasis on the execution part of the name, any corresponding narrative will naturally focus on real activities involved in the production process – including all information associated with the intent, methods and results of that process. MES originated as an attempt to simply fill a functional void left by earlier development of MRP and ERP systems; but over recent years, its scope has evolved to include nearly every aspect of manufacturing operations management.
In addition to the original core functions of planning, scheduling, executing and tracking, the term MES now also covers other aspects like batch management & execution, product & quality management, and manufacturing intelligence. While all of these are important to the manufacturing function, it’s the core execution aspects of MES and their relationship to plant-floor automation systems that will be the focus of this first of a two-part blog series.
Many MES implementations exclude plant-floor details
Plant automation personnel play a role in any successful MES project, but it is generally the IT folks who are responsible for implementing software-intense MES projects. MES is considered part of the enterprise integration side of a business improvement strategy – which, as previously mentioned, also includes ERP. This is IT’s turf, so they typically comprise most or all of the team charged with specifying, designing and executing these projects. Manufacturing IT professionals spend most of their time dealing with upward-facing details of the integration pyramid, so IT’s reach seldom extends into the realm of plant-floor automation.
As another major contributor to any MES effort, operations management has intimate knowledge of the business side of manufacturing, but are even less likely than IT folks to have much understanding of the details associated with plant automation systems. As a result, MES deployments typically result in plant-facing interfaces that just push data and commands down into the "black box" of plant automation – expecting that intended actions occur and appropriate data returns. For the most part, this method works well enough – but how much efficiency and accuracy is lost in a method that ignores a critical piece of the system? Certainly enough to give a competitive edge to the company which doesn’t ignore it, I would contend. Data governance, proper verification of actions, production agility and engagement of operating personnel are just some of the benefits gained through a fully integrated comprehensive design approach.
Comprehensive system design maximizes results
MES needs action An MES solution is supervisory by nature, and focuses on when and why process actions should occur, but doesn’t have any direct ability to carry them out. For this reason, an MES cannot stand alone; but instead, must rely on one or more process automation systems to accomplish the desired actions in accordance with the required accuracy and time frame. So it is clear that some sort of integration with the plant-floor automation system is not optional – just the quality or completeness of that integration.
ISA-88 can simplify MES integration Based on well-developed object-oriented design techniques, ISA-88 breaks down equipment and process functionality into modular entities which are readily configured into a flexible, straightforward system of easily distinguished parts. Gone are the days of highly interactive logic (aka spaghetti code) with no clear interface between functions, components or systems. In its place is a highly structured and modular framework based on a real-life model of physical equipment and procedural operations. The highly structured nature of ISA-88 solutions are a perfect fit for a well-designed, clearly-documented MES.
Interfaces for production commands and data are easily defined and intuitively understood. Functions are easily arranged and supervised to fit the requirements of the MES, and are likewise easily reconfigured to accommodate future changes. Also, when automation functions are closely matched with intended MES actions, results are more easily verified – not just assumed. All MES implementation strategies require some degree of integration, with the depth of that integration often dictating the quality of the result. When appropriate scope, representative resources and a thorough design approach all come together in the same project, good things result.
Operating efficiency is improved, performance and production capacity is raised, agility is enhanced and sustainability is achieved. Results like these are always intended, but not always achieved. A comprehensive system design which includes both MES and plant-floor automation details will yield the most complete rewards from hard-won financial investment in an MES-centered business improvement effort. In the next part in this blog series, more explanation will be given to the details and benefits of integrating MES with automation systems based on ISA-88 principals. Click this link to read Part 2 of this blog post series on ISA-88.
About the Author
Rick Slaugenhaupt is a consultant for MAVERICK Technologies with more than 30 years of industrial controls experience. Prior to joining MAVERICK, he served as a plant engineer, software designer and independent consultant for small and large companies alike. His work has involved all aspects of engineering design & construction of production equipment, processes and systems for continuous and discrete manufacturing, metals, powders, chemicals, water treatment, facilities management and security.