Siemens SIMATIC NET PROFIBUS manual Bus Topologies, Example of a Bus Topology with OLMs

Topologies of SIMATIC NET PROFIBUS Networks

Bus Topologies

Figure 2-3 shows a typical example of a bus topology

In a bus structure, the individual SIMATIC NET PROFIBUS OLMs are connected together in pairs by duplex fiber-optic cables.

At the start and end of a bus, OLMs with one optical channel are adequate, in between, OLMs with two optical channels are required.

The DTEs are attached to the electrical interfaces of the OLMs. Either individual DTEs or complete PROFIBUS segments with a maximum of 31 nodes can be connected to the RS-485 interface.

OP 25 ET 200M

À	À
2	2
PG
	À

À

3

1

Bus connector

ET 200S

À

4

À

1

OP 25

À

4

À

1

ÀTerminating resistor activated 1 FO cable

2 LAN cable for PROFIBUS

3 PROFIBUS 830-1T connecting cable

4 PROFIBUS 830-2 connecting cable

Figure 2-3 Example of a Bus Topology with OLMs

2-8	PROFIBUS Networks SIMATIC NET
	6GK1970-5CA20-0AA1 Release 2 05/2000