ABB AC 800M, User Manual

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3BDS009029R5001 B 57
Section 3 Fieldbus Topologies
Overview
Fieldbus systems are used as a means of communications for serial data exchange
between decentralized devices on the field level and the controller of the process
supervision level.
In addition to intelligent Transmitter and Actuators with a direct connection to the
fieldbus, intelligent Remote I/Os are also used as interface systems for conventional
4...20 mA or HART field devices to record process data on the field level. All
relevant signals such as input and output data, parameters, diagnostic information,
configuration settings and – for a wide range of applications – the power required
for operation can be carried over two wires (PROFIBUS PA).
There are several possible topologies for fieldbus networks. This section will
illustrate some of these possible topologies and discuss some of the characteristics