March 23, 1998 Design News
Exclusive interviews with technology leaders
Future factories need a uniform fieldbus
Wolfgang Blome, Chief Executive
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
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.
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
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.
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.