Rockwell Automation Logix5000 Controllers IEC 61131-3 Compliance Programming Manual - Manual (Page 9)

Rockwell Automation Publication 1756-PM018C-EN-P - November 2012 9
Chapter
1
IEC61131-3 Compliance
Introduction The International Electrotechnical Commission (IEC) has developed a series of
specifications for programmable controllers. These specifications are intended to
promote international unification of equipment and programming languages for
use in the controls industry. These standards provide the foundation for
Logix5000 controllers and the Logix Designer application.
The IEC programmable controller specification is broken down into five separate
parts each focusing on a different aspect of the control system:
• Part 1: General Information
• Part 2: Equipment and Requirements Test
• Part 3: Programming Languages
• Part 4: User Guidelines
• Part 5: Messaging Service Specification
The controls industry as a whole has focused on part 3 (IEC61131-3),
Programming Languages, because it provides the cornerstone for implementing
the other standards and provides the most significant end user benefit by
reducing training cost. Because of this, only IEC61131-3 is addressed here.
The IEC61131-3 programming language specification addresses numerous
aspects of programmable controller including the operating system execution,
data definitions, programming languages, and instruction set. Components of the
IEC61131-3 specification are categorized as required by the specification,
optional or extensions. By so doing, the IEC61131-3 specification provides a
minimum set of functionality that can be extended to meet end user application
needs. The downside of this approach is that each programmable control system
vendor may implement different components of the specification or provide
different extensions.