PLCopen

Based on application requirements and project specifications engineers are required to use or select a wide range of Motion Control hardware. In the past this required unique software to be created for each application even though the functions are the same. PLCopen motion standard provide a way to have standard application libraries that are reusable for multiple hardware platforms. This lowers development, maintenance and support costs while eliminating confusion. In addition, engineering becomes easier, training costs decrease, and the software is reusable across platforms. Effectively, this standardization is done by defining libraries of reusable components. In this way the programming is less hardware dependent, the reusability of the application software increased, the cost involved in training and support reduced, and the application becomes scalable across different control solutions. Due to the data hiding and encapsulation, it is usable on different architectures, for instance ranging from centralized to distributed or integrated to networked control. It is not specifically designed for one application, but will serve as a basic layer for ongoing definitions in different areas. As such it is open to existing and future technologies.

ABB is a member of the PLCopen organization. More Information about PLCopen can be read on the PLCopen website

PLCopen Motion Control logo

Function Blocks according to PLCopen are designed for controlling axes via the language elements consistent with those defined in the IEC 61131-3 standard. It was decided by the task force that it would not be practical to encapsulate all the aspects of one axis into only one Function Block. The retained solution is to provide a set of command oriented Function Blocks that have a reference to the axis, e.g. the abstract data type Axis, which offers flexibility, ease of use and reusability.

Implementations based on IEC 61131-3 (for instance via Function Blocks and SFC) will be focused towards the interface (look-and-feel/proxy) of the Function Blocks. This specification does not define the internal operation of the Function Blocks.

PLCopen Motion Control Function Blocks can be used in any IEC 61131-3 programming language. The following picture shows an example of a Function Block used in Function Block Diagram (FBD) language.

Command for absolut positioning according to PLCopen standard

Application programs which use the manufacturer independent Function Blocks according to PLCopen will lead to the following advantages:

• Reuseable software structure for different platforms.
• Programming based on Function Blocks.
• Function Blocks can be used in any IEC 61131-3 language.

All Function Blocks which are defined by PLCopen will have the following qualities independently to the manufacturer of the Motion Control system:

• Same inputs/outputs
• Same functional behavior
• Same name

The following parts of the PLCopen Motion Control definition are completely or partly included in this product:

• Part 1: Function Blocks for Motion Control
• Part 2: Extensions
• Part 3: User Guidelines
• Part 4: Coordinated Motion
• Part 5: Homing Procedures

• Programming Guidelines
  • Axis Data Type AXIS_REF
• The Single Axis State Diagram
• Visualizations
• Error Codes
• Error handling
• PLCopen Parameter
• Limits
• General Restrictions
• Behavior of the Function Block Inputs and Outputs
  • General Rules
  • Why is the command Input edge sensetive?
  • The Input ContinuousUpdate
• Unit of Length
• Aborting versus Buffered Modes
• Examples