Introduction to Industrial Automation

8.1   Topology of a Network

The term “topology” refers to the way in which the PLCs of a network are joined together or, in 

other words, to the shape of the graph formed by interconnected lines. The topologies of networks 

are derived in two basic ways from their node interconnection, point-to-point connection and multi-

point interconnection. The first consists of a circuit that connects two PLCs of the network without 

the interference of any intermediate node, while the second consists of a communication line that 

is shared between more than two PLCs in the network. Generally, industrial network topologies 

have various forms regarding the natural method of their node interconnection. The most prevalent 

topologies are the star, the ring, and the bus and these are analyzed in the following subsections.