Programmable Controls Encompass a Wide Range of Functions and Components

Programming Still Split for Control: Languages Vary, but PLCs Aren't the Only Intelligent Components in the Machine Automation Mix

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In a recent ControlDesign.com survey (www.ControlDesign.com/program), a third of participants who use PLCs for control reported their programming languages comply with the IEC 61131-3 standard; another third said some of their languages comply with IEC 61131-3; and the rest said none did because because they use their PLC vendor's version.

"Manufacturers often add enhancements to the basic IEC 61131-3 capabilities within one or more of the languages," explains Chris Radley, senior product line manager, Kollmorgen (www.kollmorgen.com). "Since these enhancements are outside the standard, they will not be transferable to other manufacturers' implementations of IEC 61131-3. The enhancements are typically additions, not changes, to the language's basic capability so if the user does not use the enhancements and stays within the basic structure and commands of a given language, it will be transferable."

Portability of the logic is at the foundation IEC 61131's benefits, says Ed Sandlin, product management, OEM solutions, Schneider Electric (www.us.schneider-electric.com). "The best portability occurs in the text-based languages," he explains. "Feature-rich structured text provides superior programming capability, management of resources and most importantly, the greatest ease of portability. Ladder logic by contrast has the highest utilization, not because of its efficiency, but because of its familiarity."

The different IEC 61131 programming languages allow the user to mix and match in one program and to select the best-suited language for a given programming task, explains Bjoern Falke, product marketing lead specialist, Phoenix Contact Automation Systems (www.phoenixcon.com). "While some tasks may be fastest to program in ladder logic, more complex instructions are handled much more easily in structured text or function block language," he says.

"With  IEC 61131-3 languages, programs are developed and executed with predictable behavior, and the code is reusable," says Kevin Hull, senior applications engineer, Yaskawa Electric America (www.yaskawa.com). "Libraries enable importation of previously developed logic."

The use of these languages produces harmonized program developments and techniques and reduces installation and troubleshooting time and the need for specialized training, says Peter Damesimo, manager, business development, c3controls (www.c3controls.com).

Using common programming languages allows programmers to be more efficient, says Eric Hollister, product sales engineer, Pilz (www.pilzusa.com). "It allows for a lower learning curve, resulting in less training for engineers and making it easier to move from one vendor to the next with less downtime," he says. "Also, if common platforms are used, diagnostics become easier."

The standard facilitates customer choice, says Michael Foley, product manager, Eaton (www.eaton.com). "That said, it does not make switching manufacturers entirely pain-free in terms of the overall investment, but it considerably lowers the barriers," he explains.

"Most recent graduates prefer function block over ladder diagram so having a software that provides seamless conversion between these helps future-proof machines that are designed to last more than 20 years," says Richard Jackson, Pan-American software product marketing manager, Omron Electronics (www.omron247.com).

 "The original idea behind IEC 61131-3 compliant languages was portability of programming allowing sections of code developed for one manufacturer's controller to be used on one from another manufacturer; it works that way in most cases for structured text, but proprietary instructions from each manufacturer prevent ladder and function block programming languages from being portable."

 Bus Controller BUS CONTROLLER
X67 CAN bus controller meets the CANopen specifications DS 301 and DS 401. Automatic baud rate detection, PDO linking, life/node guarding and emergency objects are supported. Integrated X2X Link connection makes it possible to connect additional modules. AutoMapping is used to automatically detect these modules, whose data is then placed in the I/O map. Sixteen digital channels can be configured to operate as digital inputs or outputs.
B&R Industrial Automation
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 Controller COMPACTRIO
cRIO-9023 controller has a 533 MHz PowerPC processor, and the cRIO-9025 controller has an 800 MHz PowerPC processor, as well as dual Ethernet ports for network programming, communication and expansion I/O. Both controllers work with the existing CompactRIO reconfigurable chassis, which include field-programmable gate arrays (FPGAs) that are programmed using LabView 2009 graphical system design platform. In addition to an extended operating temperature, the new CompactRIO controllers are available with conformal coating.
National Instruments
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 I/O Processor SNAP PAC

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