If you’ve been in manufacturing long enough, you’ve probably come across standards such as MESA-11, ISA-95, the Purdue Reference model, and so on.
If you’re in IT, chances are you or one of your colleagues is very passionate about one or all of these.
But if you are like the rest of us, all these terms just seem confusing and you wish there was an easy way to understand them.
If that’s the case, we got your back!
We’ll now demystify these standards for once and for all so you can impress all your colleagues next time you find yourself discussing MES over lunch. (They may also come in handy to put your kids to snooze.)
So, why all the standards? The reason behind them is simple: as more vendors started riding on the MES buzzword wave, the term became increasingly diluted.
MESA, ISA-95 and other standards came about as an attempt from various organizations to standardize the MES definition.
The MESA Model – defining MES by function
MESA, the Manufacturing Enterprise Solution Association, was created in the 1990s in order to advise on the execution of MES systems and address their growing complexity.
Their model is perhaps the most widely used in the industry as it dates back to 1997, when MESA formally defined the scope of MES through 11 core functions, called the MESA-11 model.
Though the actual model has gone several iterations over time, the one thing that has remained the same is that in order for a system to be an MES, it must have all the functional groups, or a reasonable combination of them.
That is, MESA defines MES by function.
Its current version, from 2008, spans from production, to plant operations, to business operations, and even to strategic initiatives such as lean manufacturing, quality and regulatory compliance, product lifecycle management, real-time enterprise, asset performance management, and others.
ISA-95 defining MES by system architecture
In contrast to the MESA model, which is fundamentally a business process model, the ISA-95 model is, in essence, an information model.
ISA-95 was jointly developed by the International Society of Automation (ISA), formerly known as the Instrumentation, Systems, and Automation Society, and the American National Standards Institute (ANSI).
The development of the ISA-95 standard began in 1995 when computers began to penetrate manufacturing’s information and control systems.
The ISA-95 model divides production systems into 5 levels, based on the Purdue Enterprise Reference Architecture (PERA) model.
In this way, the ISA-95 standard helps define boundaries between systems. Intelligent devices, such as sensors, belong to Level 1. Control systems such as PLCs , DCS, OCS, belong to Level 2. MES, belong to Level 3. ERP to level 4.
Other attempts to standardize MES
The MESA and ISA-95 models are perhaps the more widely known and used definitions of MES. However, there have been a few other attempts worth discussing.
One is NAMUR, which was developed by a group of end users particularly involved in the process industry (chemical and pharma for the most part).
The reason this is worth highlighting is that MES definitions might vary from industry to industry as the regulatory and operational needs change between verticals.
For example, process verticals view MES as the machine and plant control systems, while discrete industries view the MES as more of an online information system, a feedback and control system for production.