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Product category: Plant- and Machine-Wide Communications
News Release from: The Profibus Group | Subject: Profinet
Edited by the Engineeringtalk Editorial Team on 17 March 2006

Network links devices in car plant

System links more than 60 independent, intelligent devices at VW's Wolfsburg factory to guarantee availability and save time and money in engineering, design and commissioning.

Durr has implemented a Profinet system that links more than 60 independent, intelligent devices at Volkswagen's Wolfsburg factory in Germany, where it has played a crucial role in the paintshop for the VW Golf, Lupo and Touran models since March 2002 Not only have the Profibus and Ethernet networks guaranteed the plant availability, but they also saved time and money in the engineering, design and commissioning phases

The factory installation followed trials of Profinet at Durr's technical training facility.

All communication relationships were planned using graphical software tools, resulting in a modular system that led to savings being achieved in engineering and commissioning.

Durr provides production systems and in-production services for the automobile industry and its component suppliers, and the paint systems division plans and installs entire paintshops for automobile manufacturers throughout the world.

For many years Durr has provided tailored paintshops based on a modular concept that takes advantage of the product, process and project know-how that has been built up over decades.

For example, Durr Ecodim is a distributed intelligent module control system based on Profinet and distributed automation - and this is what is in use at VW.

Benefits of modularisation include a reduction in design time, ongoing cost savings, improved quality assurance (Durr aims for zero defects) and simplification of complex structures.

In modular plant construction, each plant section forms an independent module consisting of mechanical, electrical and electronic systems, the system's control intelligence and the system's user programs.

This is made possible by intelligent field units or peripheral units, each with their own CPU.

Modular systems can be expanded more easily and are simpler to maintain thanks to manageable functions.

Furthermore, the software for specific modules can be updated with no risk of undesirable effects on the other system sections.

For instance, as a result of modularisation, the Durr Ecocure dryer systems are flexible and maintenance-friendly.

The versatile dryer modules are combined so as to meet process engineering targets and are supplied to the construction site preassembled.

The modular design speeds up the installation procedure and the commissioning of the systems.

Moreover, the modular concept simplifies quality management, making it easier to guarantee uniformly high quality.

Distributed automation based on Profinet has made it possible to implement modularisation consistently and to reduce the complexity of the system.

Engineering tools such as Simatic IMap play a role in this.

These tools mean that the communication relationships between intelligent units no longer have to be explicitly programmed but can simply be planned graphically.

Within shop nine at Wolfsburg, a basecoat area with Durr Ecodim has been implemented on the basis of distributed automation.

The basecoat area consists of pretreatment, cathodic dip coating and a dryer for gradual drying of the base-coated bodies.

The individual system sections are implemented as autonomous units.

For instance, the continuous-flow dryer consists of the following modules: six Ecocure Hotbox convection recirculating-air units; one Ecocure Hotbox Freshair fresh-air unit; one Ecopure Tar thermal exhaust-air cleaning unit; one Ecocure Fanoven Exhaustair exhaust air unit; one Ecocure Coolbox cooling zone; and two Ecocure Door rolling shutter doors.

Each Ecodim module contains a distributed Simatic ET 200S peripheral unit with its own CPU.

These have been programmed with Step Seven and are networked via Profibus.

Profinet uses proven software component technology.

Programming of the internal functionality of the individual technological modules is separate from engineering and project planning for communications.

The entire functionality of the technological module is mapped and encapsulated as a software component, the Profinet component.

Access to the interface of this component is uniformly defined with Profinet.

Those variables required for interfacing with other components - for visualisation and for networking with the management level - are provided at the component interface.

On the system for VW, each Simatic ET 200S peripheral unit was first programmed with Step Seven.

Input and output variables for the component interface were then defined from a technological point of view in a data block (for example, 'Open roller shutter door', 'Roller shutter door is open' and 'Entry stop').

Finally, an XML file was generated on the basis of this information using the 'Create Profinet component' function in Step Seven.

This file describes the entire component in a standardised form that conforms to the Profinet conventions, including a reference to the related Step Seven project.

All the components for the Ecodim modules were then imported to the Simatic IMap engineering tool that provides an overview of the entire system.

The communications relationships between the components are defined graphically with the IMap tool.

To do this, the components must be retrieved from the library by dragging and dropping them onto the connection plan, where they are represented with their technological interfaces independently of the bus system used.

The communications relationships between the components are then defined by dragging lines.

Compared with using conventional complex communications programming, this graphical linking of the inputs and outputs of the components reduces the time required for the implementation and commissioning phases.

Overall, more than 60 intelligent components were connected in this way for the VW project.

The Simatic Net Profinet OPC Server, running on a PC, is used for visualisation of the entire system, which has about 30,000 variables.

As with the communications relationships, the visualisation variables were planned using Simatic IMap (the variable list is the OPC tag file in this case).

Between 10 and 20 Simatic ET 200S stations are connected via Profibus in each of the individual system areas, and the system areas are connected with a higher-level Ethernet network.

Visualisation and engineering are also performed via this Ethernet network.

Networking the Profibus segments with the Ethernet network is performed via Ethernet-Profibus links with a Profinet proxy function (Simatic Net IE/PB link).

These IE/PB links operate as proxies for the intelligent Profibus units with respect to the Ethernet units.

The advantage of this concept is that the existing extensive range of intelligent Profibus units, such as the ET 200S in this system, can be used directly.

The unchanged DP protocol is used for Profibus, and the new Profinet communication mechanisms (TCP/IP and DCom) are used for Ethernet.

For a plant and systems house such as Durr, Profinet is a further step towards consistent modularisation and decentralisation.

Reusability of the technological modules enables both time and money to be saved in engineering, design and commissioning.

In this project, the ability to use proven Profibus products was particularly important for both Durr and the system operator, VW.

In addition, the availability of the system, which operates in three-shift mode, has been guaranteed at all times.

In today's automation environments, machines and systems can generally be easily split into autonomous technological modules consisting of mechanical system, electrical-electronic system and user software; these are able to co-operate with each other using a manageable number of handshake signals.

Profinet is based on the object-oriented modelling of technological modules, with machines, systems and their parts treated as technological modules whose functionality is encapsulated in the form of Profinet components.

These Profinet components are accessible via uniformly defined interfaces.

A distributed automation system designed in this way allows modularisation of machines and systems and therefore reuse of such modules.

Profinet specifies an open, object-oriented communication concept based on protocols such as TCP/IP, which is also used in Ethernet.

The DCom Wire protocol, which allows communication of applications on an object basis, is implemented using this basic mechanism.

A vendor-neutral engineering concept has been defined for Profinet, enabling engineering and project planning of such systems to be extremely user-friendly.

It is based on an engineering object model that not only allows the development of engineering and project planning tools that can use the components of various manufacturers, but it also enables additional manufacturer or user-specific functionality to be defined using facets.

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