PMX - control system combines high-quality measuring and testing technology in mechatronic systems

The demand and requirements for products used in our daily life are becoming more and more pronounced. This is evident for example in the increasingly shorter model cycles of products, whether for electronic devices like TVs and mobile phones or in the model initiatives of automobile manufacturers.

And manufacturer must respond to this trend. They do that by creating and modernizing test and production systems designed for maximum flexibility. The same rule always applies in these situations: Reduce the diversity of components like hardware, components and software. That appears contradictory at first in view of the fact that the time required for setup, operation and (remote) maintenance of systems must be consistently shortened to keep the cost framework as low as possible so it remains competitive. How can all of this be achieved?

This article deals with the following issues:

  1. Market requirements for mechatronic systems and how they have changed over time
  2. Tasks of modern control technology
  3. What benefits does high-quality measurement technology provide?
  4. How do Smart Functions help in testing and production technology?
  5. Modern automation concepts and efficient diagnosis

1. Market requirements for mechatronic systems and how they have changed over time

Gone are the times when entire departments were furnished with appropriate resources to design and advance product development and production systems individually. These solutions often consisted of highly specific designs that were not reusable. Frequently the interaction between the individual components of a system was only possible through complicated transfer channels and interface converters. To design these increasingly complex systems ever more efficiently, there has been a consistent shift over the course of time to uniform interfaces and components taken as building blocks from a modular system.

Similarly, product developers and production planners are looking for flexible systems which offer easy integration of new technologies. Another factor to consider is that retraining should not be necessary with each new release. Hence a fundamental distinction must be drawn between automation tasks and product development tasks. Product development requires precise measured value acquisition with high recording rates. In automation applications, on the other hand, sequences must be performed in deterministic real time to run the machines in an optimum operating state, with low priority for measurement data as opposed to high priority for diagnostic data. These once distinct areas have long since grown together in mechatronic systems. Ideally components provide sufficient flexibility to be used in both areas.

2. Tasks of modern control technology

The same applies to testing and control software. Measured quantities from the test field must be saved and analyzed with suitable software. Due to the large data quantities involved, this software is PC-based and is transferred via an Ethernet interface to a measurement computer. Parts and methods of the evaluating software will then be reused later in the production environment, in combination with parts of the control technology.

In addition, a high degree of real-time behavior is often required for mechatronic system in production environments to guarantee smooth interaction between all the components without any errors. Control software that runs directly on the target systems, embedded in the hardware, is ideally suited for this purpose. Nevertheless, project planning should be convenient and troubleshooting (debugging) simple. A uniform basis was created for this purpose in the early 1990s with standard IEC61131. All controllers today are based on it. It arose essentially from the purely electromechanical controllers available up to that time, which were based on relay and mechanical control technology.

With the advent of electronics in automation, many manufacturers developed programmable logic controllers (PLCs) which followed this standard. This constituted significant progress for users in the direction of simplification. But users were still tied to one or another PLC manufacturer, so it was only natural to make standardized control functions available to them as well as a software solution. That led to Soft PLC CODESYS, which has become established worldwide.

Today's CODESYS control software, standardized according to IEC61131-3, provides an ideal, mature automation tool containing numerous predefined functions and methods for application developers. Modern methods of programming were also implemented. After the application has been created and tested, it is translated into machine code by a compiler and transferred to the target automation system.

3. What benefits does high-quality measurement technology provide?

The market is demanding new products with more functionality and higher quality in less time. The challenge for manufacturers is to make use of previously tested measurement and testing components in a production environment to fulfil quality requirements, and especially time-to-market. Development and prototype construction require high-precision measurement technology with an accuracy class of 0.05 or better plus high sampling rates to be able to measure and document the slightest changes in measurement objects. This is the only way to record product and quality features precisely and ensure repeatability. Measuring devices must have the appropriate measuring and signal quality to do this.

This demonstrates that as demands for the quality of the final product and production systems rise, more accurate sensor systems and measurement acquisition are necessary. Conventional programmable logic controllers (PLCs) cannot achieve the required quality. Only measuring amplifiers such as PMX, with high signal resolution (24-bit) and an insensitive converter input stage can meet these requirements. The carrier frequency method is recommended for this purpose: The measurement signals are first modulated and then amplified. This eliminates system-induced interference effects such as AC hum and thermoelectric voltages.

Important: All measurement channels, regardless of their configuration level, are recorded at a sampling rate of 19,200 Hz. In this way the PMX measurement system allows for an overall performance of 400,000 measured value per second, a level that can never be achieved with conventional PLCs (programmable logic controllers). This shows the limits of those systems, which can no longer be given serious consideration for high-quality measurement and control tasks.

The PMX data acquisition system, on the other hand, has different interfaces that can be used depending on the application. Ethernet is available for measurement data acquisition with the widely used TCP/IP protocol for saving large amounts of data on an external evaluation system. Real-time-capable fieldbuses like CAN, EtherCat, Profinet and Ethernet/IP can be used in PMX for automation. With the multi-client capability of PMX, all data and diagnostic information as well can be used in parallel on all these interfaces. This combination is unique in the automation world. It saves considerable resources for users in planning projects and creating applications.

4. How do Smart Functions help in testing and production technology?

PMX web browser PMX is very easy to operating by touchscreen.

Users and system operators are familiar with the operating convenience of modern smart devices and use them daily. Now PMX brings this convenience to measurement and test technology for the first time – a software and operating technology until now known only in smart phones and tablet PCs. Standardized interfaces also provide convenient access to all device parameters for configuration, operation and analysis, via any Internet-capable terminal device. The result is maximum future-proof investment security for PMX users.

The browser-based PMX software is setting standards in performance and usability. All the user needs to operate the software is an Internet-capable terminal device. The device's web browser provides quick and convenient access to all measuring, diagnostic and production data for service and maintenance or to evaluate processes.

Enhanced process reliability: Three different user levels with corresponding rights ensure maximum protection against unauthorized access for PMX and all processes. This eliminates software installations, which are time-consuming and prone to errors. The combination of Ethernet technologies and Internet also allow for inexpensive remote maintenance. Administrators and users in production benefit from all these factors.

5. Modern automation concepts for test shops and production with efficient diagnosis

CODESYS development software and web visualization

As mentioned above, the standardized control languages based on IEC61131-3 are a worldwide standard in process and factory automation. All PLCs ultimately run on them. That includes systems for press manufacturing, book and newspaper printing as well as manufacturing of furniture and components for motor vehicles.

HBM's PMX measuring amplifier now has an integrated control unit for real-time applications. It is based on the CODESYS V3 software platform from 3S and the IEC 61131-3 programming system. All programming languages in that system are supported. For the first time, this brings together premium noise-free measurement technology and worldwide standardized control technology, opening up new automation solutions for users including target and web visualization. Tools are included as standard features to ensure efficient coding.

Additional applications include energy automation, mobile automation, embedded automation and building automation. PMX is used in these cases for controlling smaller solar systems, hydro power plants, integrated weighing and filling control, medical systems, lighting and monitoring of climate control. CODESYS, the comprehensive software suite for automation technology, includes everything users need for programming, fieldbus and I/O configuration, visualization, motion control and other tasks, including even customized plug-ins such as functions and libraries.

The individual modules that were implemented in PMX include:

CODESYS engineering:

Professional engineering of IEC 61131-3 applications for specialists and software engineers – in one expandable platform. The Structured Text (ST) programming language in particular is for the most part equivalent to high-level languages like C/C++. In addition to useful auxiliary functions such as Intelli-Sense, AutoComplete and syntax error detection, object-oriented programming (OOP) was also implemented. It is increasingly used by innovative programmers who need to create and manage program code in ever shorter timeframes. Tools are included as standard features to ensure efficient coding. That includes functions and libraries as well as static program code control for code analysis, a profiler to optimize code and a manager to create test scripts for the program code. 

CODESYS fieldbus:

Integrated support in the IEC 61131-3 tool (i.e. the CANopen interface, still widely used, is supported in PMX). It can receive data (CAN master) or send CAN data (SDO/PDO mode). That makes it possible to integrate additional CAN-based field modules flexibly into a PMX system and adapt them to the relevant requirement. Signals or measured values can be read in via CAN and actuators can be controlled and regulated using the CAN interface.

CODESYS visualization:

Creation of professional visualization interfaces, fully integrated into the PLC programming system. Display on the target device, on a PC or in the web browser. CODESYS contains an extensive library of visualization and control elements in a modern design from which users can choose the elements that exactly meet the requirements of the application. The entire visualization can easily be changed by simply switching stylesheets. Users can also create their own styles, in addition to the pre-defined ones.

CODESYS store:

The programmer chooses from a collection of executable programs and libraries in this online market place. Code from the store, operated by 3S, has been tested before publication. Users can publish their own code and they can choose whether it will be free of charge or if other users will have to pay to use it. This is a very efficient way to save time and expand functionality, one we are already familiar with and use in the consumer market in the form of the app store.

CODESYS security:

Protecting know-how has become a top priority for many companies, and that includes software solutions. The CODESYS integrated into PMX offers several possibilities in this regard. One is the application project: Project files and libraries can be encrypted with passwords or the CODESYS Security Key (USB dongle).

PMX with CODESYS control and web visualization

Another is project-specific user management of individual program modules. A third possibility is on the target device (PMX), using definable user profiles for access protection with the applications, control unit and visualization. Other effective methods include encrypting the boot application or encrypted communication for applications that are running.

A CODESYS runtime license is already included in PMX with the WGX001 basic device. The CD included with delivery contains the CODESYS development software V3.5, the corresponding PMX package and a collection of helpful sample programs for generating code, web visualization and integrating CANopen modules. With HBM, users have everything from a single source. HBM delivers the entire measuring chain with a matching software solution. HBM experts evaluate the task and manage the project – from creating the program to finished application with all the necessary documentation.

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