Siemens SIPROTEC Manual page 35

Switchover.req
via RedCom
received
PB_Switchover
Master state: PRIMARY
Wait for changeover of the
master state to BACKUP
BACKUP state
received
from master
Figure 1-12 Redundancy switchover state diagram (simplified)
SIPROTEC PROFIBUS DP - Bus mapping 6MD662/3/4
C53000-L1840-B011-03
Every redundancy switchover always includes an internal communication via Red-
Com between the both modules of the redundant slave in order to ensure that both
modules never become PRIMARY at the same time.
Beside PRIMARY and BACKUP, the slave interfaces pass at least one intermediate
state during a redundancy switchover.
In these intermediate states
• PB_Switchover or PB_Partner_Ack
during switchover from PRIMARY to BACKUP
• BP_Switchover or BP_Partner_Ack
during switchover from BACKUP to PRIMARY
the modules wait for a response to a switchover request which was sent to the partner
module via RedCom or for a state change of the master device.
There is no evaluation of output data from the PROFIBUS DP master in the interme-
diate states, i.e. they behave like the BACKUP state.
The current redundancy states of the PROFIBUS DP modules on port B and port D
are shown in the module-specific information at the device display (ref. to chap. 1.5).
All possible redundancy states are described in Table 1-5.
Figure 1-12 shows a simplified state diagram of the redundancy switchover.
PRIMARY
Master state: PRIMARY
PRIMARY state
received
from master
Communic. interruption
BP_Switchover
Master state: BACKUP
Wait for changeover of the
master state to PRIMARY
Switchover.req
via RedCom
received
BACKUP
Master state: BACKUP
Switchover.cnf
via RedCom
received
BACKUP state
received
from master or
PB_Partner_Ack
Master state: BACKUP
Wait for Switchover.cnf
from partner module
Switchover.cnf
via RedCom
received
Redundant PROFIBUS DP interface
Switchover.req
BP_Partner_Ack
Master state: PRIMARY
Wait for Switchover.cnf
from partner module
PRIMARY state
received
from master
Switchover.req
RedCom:
RedCom:
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