Fieldbus communication via existing master cable

Fieldbus communication via existing master cable

Using free core pairs for fieldbus technology

Low installation effort, inexpensive networking, flexible thanks to fieldbus technology.

Your advantages

  • Low installation costs through using free core pares in master cable installation.
  • Minimal production downtime thanks to easy installation and startup
  • Large application range of up to 20 km, thanks to optimum transmission quality
  • Future-proof, thanks to extendable, integrated fieldbus installation
  • Tried and tested solution – has been in use at major German chemical companies for a number of years


During the long life cycle of a process engineering system, system parts are permanently optimized and extended, and the field technology and control technology are renewed. The switch rooms, however, are still located in the same place and the cabling installed should be operational for the entire system's service life. Sooner or later, operators are faced with the problem that reserves planned decades ago, for example, in terms of master cables will run out.

There is a number of options in such a dilemma, one of which is modern bus technology. In this case, PROFIBUS or Ethernet derivatives play a key role.

The conventionally used high-pos. master cables are not fieldbus-compatible. As such, if this technology was used until now, special standard-compliant cables (shielded, drilled core pairs) had to be laid and assembled by specialist personnel. The resulting high installation costs and longer production downtimes translate into substantial expenses for operators.

Typical signal transmission from the field to the control center  

Typical signal transmission from the field to the control center


Industrial PROFIBUS or Ethernet extenders  

Industrial PROFIBUS or Ethernet extender

A simple trick enables Phoenix Contact to potentially use the last two free cores of a master cable for PROFIBUS or Ethernet communication.

This functions over several kilometers, without shielding and even without taking the cable type into consideration. This is the conversion of the PROFIBUS or Ethernet signal to the extremely robust SHDSL technology, for example.

To start with, the bus signal is converted to an SHDSL signal (Symmetric Digital Subscriber Line), and once it has been transmitted, re-converted to the bus signal via the cable route.

Communication on this cable route is transparent and is not to be detected by the master. As such, time-consuming integration and configuration of devices via a GSD or DTM file is now a thing of the past.

Serial data transmission via industrial extenders  

Industrial extenders use the last core pair for serial data transmission to a remote I/O station

If a fieldbus connection has been established, you have the following options:

  • either install a remote I/O system in the field and install a fieldbus master in the control center
  • or collect individual signals via a multiplexer in the field and jumper them to free IO cards in the control center.
left: line structure (2-wire) / right: point-to-point connection (2-wire)  

left: line structure (2-wire) / right: point-to-point connection (2-wire)


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