Welcome to the PLCopen® electronic newsletter.
- PLCopen releases Guidelines for Object Oriented Programming, version 1.0
- PLCopen Motion Control for Robotics
- PLCopen restarted working group Administration Asset Shell
- PLCopen Benchmarking – a different approach
- PLCopen sponsors 26th Annual ARC Industry Forum in Orlando, USA
- PLCopen Motion Control – new certifications
The 3rd edition of the IEC 61131-3 standard enables the usage of Object Oriented Programming, OOP. With Object Orientation one can make many additional choices in the way the program is structured and decomposed, providing a different look & feel to the users especially across the different systems and platforms, creating different training guidelines and differences in maintenance.
To support the right choices and to add to the training programs, PLCopen started an OOP Guidelines initiative, in order to create a more homogeneous method. This activity helps to understand to make the right choice upfront, and to create consistent programs with long-term support.
PLCopen was already involved in OOP with the definition of PLCopen compliant function block libraries, which included both object orientation and classical programming (procedural). With the specification on communication via OPC UA, other OOP aspects come in. And with the security aspects within a system more OOP technology will arrive at the controller level.
This does not mean that the classical programming will be replaced: due to the upwards compatibility both programming styles can cooperate in parallel and be used in those areas that they serve best.
When one starts using OOP, several choices need to be made. These choices give a different look & feel to the users across the different systems, different training guidelines and differences in maintenance and its costs. And this is where PLCopen wants to help and give guidance to create a more homogeneous programming methodology.
Overall, there is little information on how to use OOP for industrial control or the operation technology (OT). The goal of this group is to help here with the following recommendations:
- Guidance to using OOP in addition to the “classical” way.
- Provide the same look & feel in using OOP across the different platforms and implementations.
- Create generic design patterns for industrial control programming.
- The classical programming way should be possible to be used in addition to the OOP way (e.g. this can mean that we have to extend the classical FBs with interfaces, methods, properties, and maybe input and outputs).
As an example, a boiler demo was used to represent the different forms of programming, moving from a classical approach, via a harmonized look & feel towards OOP.
We now published the first document “PLCopen Guidelines for usage of Object Oriented Programming”, as version 1.0. Within this document we show how to convert a “classical” program to an OO program. The project file is available as part of this.
This is an additional document within the framework of the PLCopen Software Construction Guidelines. The documents from this activity can be found at our website www.PLCopen.org:
- Coding Guidelines
- Creating PLCopen Compliant Libraries
- Structuring with SFC – do’s & don’ts
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In 2008 PLCopen released Part 4 of the Motion Control suite of specifications, dealing with coordinated motion, i.c. robotics. Basically, with this specification one can control a robot in the PLC or one can see it as an interface to a robotic controller, which will do the calculations and movements of the joints.
Especially for this last option we received feedback from robotics companies with specific requirements, which resulted in a Corrigendum and the basis for Version 2.0 of this specification.
Siemens went one step further with the release of their SIMATIC Robot Library. For this purpose, Siemens extended Part 4 with the knowledge from the community of robot suppliers, as many of them were involved. The extensions add the configuration section as well as additional functionalities. And from a networking perspective it is open, so not limited to Profinet only. Also, we want to make sure that it supports many different kinematic models.
Siemens offered their Robot Library to PLCopen, which gives us the opportunity to update the interface of Part 4, esp. on the controller side. In this way it can easily be coupled to robot controllers of the different robot suppliers, while supporting other kinematic models.
Contact PLCopen if you want to be part of this activity.
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Industrie 4.0, is a movement that has great impact on the world of industrial automation. It is about software. And so is PLCopen.
PLCopen has defined many software functionalities via the definition of Function Block Libraries, as done for Motion Control, Safety, and for Communication over OPC UA. These PLCopen specifications provide a well-defined suite of functionalities, covering the basic range. In addition, PLCopen defined a framework related to the definition of function blocks with a focus to the create user defined libraries. In this way one can encapsulate larger functionalities and provide higher levels of integration. This makes the engineering of a new machine more easily and provides a better decomposition and reusable structure in the software development, making it easier to maintain and add new wishes.
Basically Industrie 4.0 consists of two main items: the RAMI model and the Asset Administration Shell. In the RAMI model the standard PLCopen functionalities fit very well and so PLCopen focuses on the Asset Administration Shell, AAS. And in this shell PLCopen want to add their functionalities.
To be able to access these functionalities in AAS and make it available to the application running on the controller, PLCopen is defining a set of Function Blocks. In this way the programmer can access the relevant information in a harmonized way.
In addition, PLCopen is working on a document showing the integration of PLCopen and PackML via the PLCopen OPC UA profile. Following some basic rules for the application development, it will become much easier to interface to a machine in a harmonized way and to integrate machines in production lines in a standardized way, based on OMAC PackML state machine, modes, and Packtags. With the combination of the OPC UA functionality for browsing, one can even search for new functionalities and add them as the basis for a new application program more easily.
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During the SPS, PLCopen shows several areas of activities: from guidelines to use the Object-Oriented Programming within the industrial environment, the extended harmonization of the interface towards robot controllers, and benchmarking.
“PLCopen Benchmarking is something different at PLCopen for 2 reasons”, says Eelco van der Wal, Managing Director of PLCopen. “Although PLCopen normally deals with the software environments, it was the best choice to define a benchmarking tool for measuring the performance of the different CPU architectures. Nowadays the CPU suppliers can tune their architectures to the specific needs. However, the needs of the industrial world in general are not clearly specified for them. The strict need for the real-time processing parallel to other operations is not so much known in other industries and needs clarification between the CPU suppliers and the control suppliers.”
PLCopen did benchmarking in the past with a focus to different user applications, including motion control. However, the network seemed to be the decisive factor and further development was stopped. Today Benchmarking is back on the drawing board, but with a different scope. Therefore, PLCopen started this new approach.
This PLCopen benchmarking workgroup has a hardware resource-oriented approach, like processor- and computing-architecture. With this new initiative, the benchmark can indicate the effective performance of the different processors and architectures as used in the industrial controllers, and thus help in the selection of the optimal architecture for the control supplier in a very early stage. By the time the IEC program can run, it is already "too late" to tune, and much time, money and effort is already invested.
This workgroup is defining a common language between the parties involved, ranging from CPU suppliers to control suppliers, and combined this with common test scripts for real-time and the influence of the other processes (“Noisy Neighbors”). This will include micro-benchmarks for the CPU specific tasks and subsets of instructions and application-oriented benchmarks. Overall, the suppliers are not looking for highest performance but for predictable, reliable, and deterministic approach at good pricing: “the best bang for the buck!”
What is also really different in the approach, is that this working group is a PLCopen internal activity. The results of this group are not for comparison between the different suppliers, but strictly for use by the members of the organization internally. This is the first not open activity in PLCopen, not including the users and end-users.
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The ARC Industry Forum is the “must attend” learning event of the year for industry executives and technology solution providers.
PLCopen is sponsoring ARC’s 26th Annual Industry Forum which takes from
February 14-17, 2022 in Orlando, Florida
March 7-10, 2022 – Online
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We are glad to announce that two members have been awarded the PLCopen Motion Control certificate:
- Kingstar with update version 4.1 of their product Kingstar (PLCopen Motion Control part 4)
- Mitsubishi Electric Corporation with update version 1.01A of their product FX5U/FX5UC/FX5UJ/FX5S/FX5-ENET, GX Works3 (PLCopen Motion Control part 1)
This brings the total number of certified companies to 28 and of certified products to 69.
For more information, please check our website www.PLCopen.org.
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