A unified network at Volkswagen

Automotive manufacture makes rigorous demands of networking technology. VW's Mosel plant is built on a Gigabit Ethernet backbone, integrating both administrative and production areas

Volkswagen Saxony in Mosel near Zwickau, Germany, manufactures Passat limousines and the Golf IV. The factory employs nearly 5,900 workers involved in the manufacture of in excess of 1,000 cars a day. In July 1999, the millionth VW rolled off the assembly line out of a total of 268,000 vehicles for the year. The communication network used throughout the factory is based on Hirschmann technology, using all three main automation product lines, from star couplers through workgroups and the GLS (Gigabit LAN switch) backbone switch to industrial DIN rail mounted Ethernet products.

Hirschmann components have been in use at VW Saxony in Mosel since 1991, and have been used in the VW corporate group for several years before that. Hence, the network has evolved using Hirschmann equipment. Two years ago, it was decided not to use ATM technology and remain with Ethernet. The perceived relative ease of controlling Ethernet technology also played an important role in the decision to go with Gigabit Ethernet in the backbone. The growing requirements of the VW Saxony network in Mosel have been met by the expansion of the Hirschmann product range.

Assembly of the Passat and Golf is to individual customer specification and therefore individual data packets regarding special requirements, such as engine size and colour, are available over the network.

Protection from failure, especially in manufacturing, and the growth of the network play a key role in network planning today. As quantity and quality of data has increased, network management has taken on greater significance and switching bandwidth and transmission speed are now factors of moderate importance.

Interference The data network at Mosel connects around 1200 users over 1.8 sq.km. The total length of cable laid for the network is over 1000km, of which nearly 70% is optical fibre to just over 30% copper cabling. The longest distances between connections on site about 2.5 km. Therefore, mono-mode optical fibre technology has also recently been installed for Gigabit Ethernet. As well as distance, resistance to interference (for example protection from electro-magnetic interference for the optical fibre lines) is a decisive factor determining usage. Multi-mode optical fibre is also used in the structured cabling (backbone, buildings and floors).

It would be possible for an employee, if authorised, to access all areas of the network which integrates more than 50 servers (Compaq, HP, Digital, and IBM), running on Windows NT or Unix platforms. Special demands are placed on bandwidth by the database applications required for the flow of manufacturing, server applications, high-resolution graphics and web applications such as internet and intranet.

All administrative areas are integrated into the network, (including accounts and human resources) as well as production areas (such as vehicle assembly, the paint shop, the trim shop and the chassis construction area which is equipped with 650 robots). Applications include: file and print service; specific databases such as Oracle, DB2, Microsoft SQL; the SAP R/2 and R/3 systems: SNA-3270 host emulations for the mainframe computer: web-based applications; email systems, intranet and internet; and online access to corporate group resources in the computer centres at Wolfsburg and Ingolstadt.

The network is very important, not only for the administrative area, but also for manufacturing. For example, the test results for final vehicle assembly are integrated into the overall data network through Ethernet Rail switches and hubs from Hirschmann's Industrial Line range.

Central databases provide information about specific customer requirements for each individual vehicle. Vehicles are identified by barcode - the information is read from a control computer and the data is then transferred to the assembly phase.

After final assembly, the data of the test results go to central control and guidance computers. In addition, the system provides information about which test cycles are necessary. For example, a vehicle with a diesel engine is subjected to different tests from a petrol vehicle.

Availability Even when planning the network for the Mosel plant, it was imperative for it to be 100% available around the clock. It also needed to be used in various areas of manufacturing such as chassis construction or the paint shop. Therefore, the active components needed to be impervious to heat, dust and vibration and had to be able to span great distances.

VW Saxony also places additional requirements on Ethernet switches and hubs used in manufacturing, so that they take up only a small amount of space and that they run on the plant's 24V DC power supply. Redundancy requirements achieved greater significance than bandwidth in the Gigabit Ethernet decision for GRS.

The greatest demand on the network is directed at its availability. The network must be available everywhere, for both administration and manufacturing. Downtime would immediately result in a significant loss to a plant producing 1100 cars a day. To avoid production failures, redundant networks are used in the manufacturing environment.

There is a good reason for the high value placed on ring redundancy in cabling. Data cables have already been damaged as a result of construction activities performed at the site. Thanks to ring redundancy, this did not result in a network crash.

"In terms of redundancy, we have made use of all the possibilities of hardware redundancy and redundant cabling structure, such as with the ASGE family, with the GRS Gigabit Routing Switch and with the Rail family," says the factory's Director of Organisation and IS Coordination Matthias MŸller. "Because of the elevated delay times, we also decided not to use the slow spanning tree.

"Redundancy is also important for us because we can no longer perform 'sneaker maintenance' as a result of the extended distances the network covers," he continues. "We have to expand the functional mechanisms that place the network independently in the position of being able to restore network functionality automatically in the event of a failure. Redundant structures in the network make it possible for us to support the network with personnel on site only between 6:00 am and 6:00 pm."

Another aspect of the economic advantages provided by the network is central management. An employee can monitor the local network from the central management station and perform remote monitoring of motor manufacturing at Chemnitz or in the customer service shop at Zwickau, for example, saving an 8-10km kilometre trip. VW Saxony is further expanding the backbone with Gigabit Ethernet. INOC

• Hirschmann
  d143@industrialnetworking.co.uk