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Motion standards move ahead

Motion standards move ahead

The OMAC packaging industry workgroup includes an influential group of end users, OEM machinery builders, and suppliers that are moving forward with initiatives that define standards for industrial motion control. The group has endorsed IEC 61131-3 as a standard development environment for programming motion and logic control, and is working to refine a library of motion control function blocks and state machine definitions appropriate for packaging machinery.

In addition to OMAC's emphasis on technical standards, the group has a focus on improving overall business and productivity results, along with increasing cooperation with other industry groups. Recent developments include new extensions to the PLCopen motion control library, cooperation with the World Batch Forum organization, and news on programs to improve business results, training programs and connectivity options.

PLCopen Part II
Targeting a formal release for the April 2004 Hannover Fair, PLCopen (www.plcopen.org) is working to introduce Part 2 of its Motion Control Library. According to Eelco van der Wal, managing director of PLCopen, the new extensions "are a clear step forward and demonstrate that we are working to improve basic motion control functionality supported by the library". He says it has made it clear what additional functionality should be added in future releases, including "stacked commands" to support both linear and circular interpolation and new functionality for homing.

The basic goal of the PLCopen Motion Control Task Force has been to develop an independent library of function blocks for motion control using IEC 61131-3. The initial release of the library includes motion functionality for single and multiple axes, administrative tasks and a machine state diagram. The specification provides the user a standard command set and structure that is independent of the underlying architecture, and has been implemented by a broad group of suppliers.

Part 2 adds a series of motion control function blocks to the library which enrich the tool set for the application programmer. A motion control touch probe provides the ability to record an axis position using a triggered event, and is useful for registration applications. The touch probe can be used with other function blocks to calculate product position and trigger asynchronous events such as printing, gluing or cutting.

A new digital cam switch function block provides "switches" on a motor shaft. These switches command a group of discrete output bits "in analogy to a set of mechanical cam controlled switches connected to an axis". Both forward and reverse rotations are supported.

A new Torque Control function block exerts torque continuously with a specified torque level using a defined ramp. If the selected torque level is reached, it sets an "InTorque" output. This function block is applicable for commanding both force and torque, and can be used for both continuous and discrete motions. The torque control additions are specifically designed to address capping applications.

Complete details on Part 2 are available on the PLCopen website (www.plcopen.org). Information is available for all the new additions to the library including new ability to read and write I/O, plus new administrative, status and reporting functions. On the website, there are also examples of how to use the blocks to design motion systems, since multiple blocks are often used to create specific application solutions.

PLCopen is also working with the OMAC PackSoft Working Group to define functionality specifically for packaging applications. Van der Wal says that group wants to use the standard naming conventions that they have already defined, and create a set of "higher level" function blocks for packaging applications based on the existing blocks in the library.

PLCopen Motion Control Library provides a set of standardized function blocks for developing motion and I/O solutions in IEC 61131-3.

Progress on Initiatives
At the annual OMAC Orlando forum, the group provided updates on the progress of the individual working groups within OMAC. More information on each of these working groups, and how your company could become involved, is available on the OMAC website (www.omac.org).

The PackAdvantage Team has completed Version 2.0 of its User Application Guide that can be used to calculate the strategic business advantages of a given automated packaging investment. This working group is now gathering examples of early adopters for presentation at this year's Pack Expo. OMAC also announced a cooperative effort with the World Batch Forum to harmonize the group's PackML Guideline with the ISA SP88 standard, from which PackML is derived.

Business Benefits
In a presentation at the Orlando forum, Skip Holmes, Associate Director for Power, Control and Information Systems for Procter and Gamble, gave a presentation entitled "Business Drivers in the CPG and the Strategic View of Packaging." Holmes correlated the investment his group has made in staff involvement with bottom line financial benefits that could reach $15 million annually by increasing reliability, quality, capacity and speed to market.

He then specifically challenged the user's group to continue to focus on solving business problems, to communicate the benefits broadly and in business terms, to expand the number of participating companies, and to drive the guidelines toward industry standards.

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