Siemens SIMATIC NET PROFIBUS - Manual (Page 18)

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