Guest commentary 3-23-98

March 23, 1998 Design News

GUEST COMMENTARY Exclusive interviews with technology leaders

Future factories need a uniform fieldbus

Wolfgang Blome, Chief Executive Director Phoenix Contact GmbH & Co., Germany

Standard fieldbus protocols will be an integral part of the future factory, says Blome.

Design News: What implications does the Internet present with regard to Interbus technology and future product design?

Blome: With the Internet there are two important information channels for the Interbus system of which we will take increasing advantage. First, the Internet allows our customers to exchange information, data, and product requirements directly with our systems specialists. Via this direct way from computer to computer, planners, programmers, and developers can obtain important information such as data sheets and project planning documents without much paperwork. In the future, orders shall also be processed via the Internet.

The second information channel involves outsourcing and the relocation of production plants to economic locations. As a result of this trend, virtual companies with worldwide distributed production units are created which have to be networked to ensure smooth production processes. For this purpose, the Internet provides a global and reasonably priced medium.

Q: Within the device network level of a manufacturing operation, what differentiates one "open architecture" fieldbus system from the next?

A: Many bus systems were developed for applications with special requirements. Afterwards, efforts were made to position these bus systems in other industrial areas. There are, for example, bus systems which were especially developed for control systems in cars; others were developed for applications in the field of building control technology or process control technology. Such bus systems usually only meet part of the tasks to be done at the device network level of a production plant.

The Interbus system was particularly developed for device networking in production plants. It universally meets all requirements of the individual network levels. In the sensor/actuator range, the Interbus system offers convenient connection systems and the necessary diagnostics. At the fieldbus level, the Interbus protocol ensures the quick and reliable transmission of I/O signals to the control systems. Between the individual controls, the Interbus allows easy telegram traffic with which even controls from different manufacturers can be conveniently networked without any interface problems.

Q: How will adaptation of a worldwide fieldbus standard impact such systems as they are presently configured?

A: Taking into account the fact that Interbus has already become established worldwide as an international industrial standard, and that it has already been standardized according to EN 50254 , Interbus users have already relied on an international standard and no longer have to carry out an adaptation in the system.

Those using bus systems which are predominantly of national importance or those using bus systems such as Can, Device Net, Lon, or Profibus may adapt their system to the international industrial standard Interbus in different ways.

If only the I/O system is to be adapted and the control system shall be maintained, adaptation can be made via gateways. Phoenix Contact offers such devices, for instance, to equip existing Profibus systems with new Interbus modules.

If the control system and the I/O modules shall be kept and only the bus system shall be replaced, this can only be done if the presently configured system is equipped with modular bus interfaces--as are, for example, available in the IBST range in the form of bus terminal modules. In this case, only the bus terminal modules and the host controller board of the control system have to be replaced by new modules.

Q: Why is implementation of a universal protocol taking so long, and when will it happen?

A: The Interbus system is a bus system with a universal protocol which was already developed years ago by practice-oriented users. Efforts to implement additional universal protocols apart from Interbus mostly fail since control manufacturers decide and not users. Since control manufacturers most often want to realize their individual interests in a uniform protocol, again and again individual solutions are created instead of a uniform protocol.

Q: Describe your vision of the future factory.

A: In the factory of the future, there won't be interface problems since a uniform fieldbus system will be used. The protocol of the fieldbus will be universally implemented from the control system to the very last sensor. The signal matching of the sensors and actuators and the transformation of the signals from an electrical size into a physical unit will be made automatically. Also, installation and configuration costs will be minimized in the future factory.