n
Number of FO couplers within the ring
T
FO coupler
Module run time of the signals within the FO coupler = 4.5 ms
L
Length of the FO cables within the ring
T
FO
Run time per metre FO = 5 ns
The values indicated in the table apply to Profibus DP .
Max. distance bet-
ween two FO
couplers [km]
T
ring
Run time within
ring [ms]
Slot time [bit ti-
mes/km]
Data rate [kbit/s]
0.7
0.30
900
1,500
2.2
0.90
900
500
2.6
2.40
900
187.5
2.6
4.80
900
93.75
2.6
9.90
900
45.45
2.6
23.44
900
19.2
2.6
46.88
900
9.6
●
The FO coupler connected to the master via copper cable has to be a master
module. Only one master module is allowed within the ring.
Cable routing and PLC fault evaluation
●
To increase service safety, install cables for go-and-return in the ring on sepa-
rate lines.
●
To achieve complete monitoring of the redundant optical ring, all FO fault indi-
cations (including the fault output of the FO coupler at the master) must be
evaluated by the PLC controls.
11
Network topologies
