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2. Installation
PROFIBUS DP requires approximately 1ms at 12 Mbps for the transmission of 512 bits input
data and 512 bits output data distributed over 32 stations. The following figure shows typical
PROFIBUS DP transmission times depending on the number of stations and baud rate.
Bus Cycle Time [ms]
500 kbps
1.5 Mbps
12 Mbps
Number of Slaves
2 10 20 30
18
14
10
6
2
The maximum cable length is restricted by the baud rate.
Baud Rate Maximum Cable Length
12 Mbps
6 Mbps
3 Mbps
1500 kbps
500 kbps
187.5 kbps
93.75 kbps
19.2 kbps
9.6 kbps
100 m
100 m
100 m
200 m
400 m
1000 m
1200 m
1200 m
1200 m
Multi-Master Configuration
PROFIBUS DP allows you to install multiple masters on a single physical network.
All slave devices on the network can be accessed by different masters. Only one master on
the network can be used for device configuration.
The following figure illustrates the communication procedure for a multi-master
configuration.
Master 1
Master 3
Slave Slave Slave Slave Slave
Master 2
Slave Slave
Token-passing Procedure
Master-slave communication
When the master receives the logic token, it inquires data from its slaves. After all
communications are completed, the master passes the token to another master. In this way,
the master can only communicate with its slaves while it is holding the token. The slaves
respond to only the inquiry from the master. No slave can output any messages.
22 Fieldbus I/O Rev.6