Advanced PROFIBUS PA Redundancy Concepts

In process automation and particularly in the area of continuously running processes, availability of the systems is of outstanding importance for efficient plant operation. To avoid unplanned plant downtimes, the redundant implementation of control and communication systems is a common measure.

For PROFIBUS PA, two new redundancy concepts are available:
Coupler Redundancy and Medium (Ring) Redundancy, both of which are based on
advanced features of new coupling devices. The new DP/PA couplers as well as the Active Field Distributors (AFD) feature integrated automatic bus terminators which insulate defective segments automatically and shock-free in the event of a short-circuit or wire break. Fig. 1 und 2 indicate to which alternative communication paths the systems are automatically switched in case of a failure to ensure uninterrupted communication.

As additional advantage the instrumentation can be altered or ring segments added or removed without interrupting operation. Further on, installation is particular easy and safe, because incorrect bus termination is impossible
The redundancy management system is part of the DP/PA couplers. Diagnostic and status information is provided by means of LEDs or is transmitted to the central control system.