A discussion of the role of standards in packaging can sometimes seem like a cross between alphabet soup and Sudoku, a kind of number placement puzzle, what with IEC 61131, ISA-88, PackML and ISA-95 among those most frequently mentioned. But despite their apparent complexity, the potential impact of these and other standards is both simple and profound. At its most basic level, say industry proponents, the widespread adoption of open packaging industry standards will lead to higher levels of integration, improved responsiveness to customer demand and reduced cost.

According to Mike Wagner, business lead, global OEM team, for Rockwell Automation Inc., Milwaukee, it starts with vocabulary. He likens manufacturing operations to book publishing. Different books will have different tables of contents, indexes, chapter headings and the like. But those involved with book publishing know what an index or a table of contents is, and how they are supposed to be structured. Publishers don’t have to invent these things from scratch.

“Similar format rules apply to manufacturing suppliers, OEMs (original equipment manufacturers) and end users,” says Wagner. “For example, the ISA-88 standard follows the ‘state model,’ a manufacturing standard that uses a defined set of terms and definitions to describe the process being controlled. OEMs are not told what words to choose, but the state model defines the vocabulary so that original equipment manufacturers are speaking the same language and using the terms appropriately. This creates a predictable, reusable model that helps ensure consistency.”

The problem is that ladder logic is a time-consuming and less-than-capable tool for programming these more sophisticated machines.

ISA-88 is the brainchild of the Instrumentation, Systems and Automation Society (ISA). By establishing standard modes for describing basic states of machine operation (thus the term, “state model”), the standard has facilitated automated data transfer between machines, including machines from disparate vendors, in the batch processing sector. More recently, the state model has been enhanced with the development of PackML—Packaging Machinery Language. Created by the Open Modular Architecture Controls Users’ Group, or OMAC (now affiliated with the ISA), PackML adapts the state model to the specifics of packaging machinery, adding new data definitions, or pack tags, to describe the basic states that all packaging machinery undergo. Importantly, its consistent data format also makes integration with manufacturing execution systems (MES) easier.

Add to the state model concept the standard with the geekiest name of all—IEC 61131—and the efficiencies really begin to add up.

As packaging machines became more capable and complex, notes Tom Jensen, senior technology evangelist for Elau Inc., a Shaumburg, Ill.-based packaging controls vendor, “machine programs grew very large to articulate the new found sophistication of machines.” The problem is, ladder logic, which has been used for decades to program programmable logic controllers (PLCs), is a time-consuming and less-than-capable tool for programming these more sophisticated machines. And, because ladder logic programs are sequential, each segment of code is dependent on previous segments, so modifying a program is difficult.

“It was commonly realized that other languages may be helpful in describing these more complex ‘Generation 2’ machines. There were many languages available from the industry, but they all suffered from one of two conditions. The languages commonly offered on the market were either text-based or graphical. Text-based languages in general were capable of describing complex objects with much less code, but were not intuitive. This meant a programmer could actually create machine code that worked well and described how that machine should operate, but nobody without programming education would be able to work on the machine. Secondly, there were graphical languages. They were intuitive but lacked depth.”

LANGUAGE POWER

This is where IEC 61131 comes in. Developed in 1992 in Europe by the PLCopen standards organization, and promulgated by the International Electrotechnical Commission, it has gradually gained acceptance through the years. It defines a suite of programming languages; a ladder language called Ladder Diagram and Function Block Diagram are both graphical languages,while Structured Text and Instruction List are textual languages. The standard also includes a higher-level “organizing principle” for “modular” programming called Sequential Function Chart. Software objects containing subroutines for specific tasks can be written, tested and reused as standardized modules. Importantly, the standard also provides for the nesting of one language inside another.

Jensen provides an example of the power of the standard. “Let’s start with making a piece of modular code for a servo motor,” he says. “Once we model the servo in a Function Block and store it in a library, we can drop it ...