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2 access techniques – Siemens SIMATIC NET PROFIBUS User Manual

Page 18

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PROFIBUS NETWORKS

1-8

PROFIBUS Networks SIMATIC NET

6GK1970-5CA20-0AA1 Release 2 05/2000

1.2.2

Access Techniques

TOKEN BUS/Master-Slave Method

Network access on PROFIBUS corresponds to the method specified in EN 50170,
Volume 2 “Token Bus” for active and “Master-Slave” for passive stations.

Slave

Master

Token rotation

(logical ring)

Slave = passive node

Logical token ring

Master-slave relationship

Master

Master

Master

Master

Master = active node

Slave

Slave

Slave

Slave

Figure 1-1

Principle of the PROFIBUS Medium Access Technique