3.3
Ring topology (two-fibre ring)
Figure 9:
Structure for ring topology
Max. FO cable range in km (observe technical data!)
[1]
FO ring coupler within electrical connection of ACExC 01.2
[2]
FO ring coupler within DCS (imperatively required)
[3]
FO ring coupler for any Profibus DP field device
[4]
Any Profibus DP field device
Information
Maximum number of FO device (actuators) connected in series is 36.
Special features of ring topology
●
The interruption of an FO cable between two actuators is recognised by the
redundancy modules. Both display and bus indicate:
Wrn FOC
. The network
is then operated as an optical line and all actuators remain available.
●
If one module fails (i.e. when power supply is interrupted), only the actuator
connected to this module is disconnected from the ring, the remaining network
stays operative as a line. All other actuators remain available.
●
The actuators have a redundant FO cable connection with a standard Profibus
DP interface (not redundant).
Special features of the ring topology during configuration
The following conditions have to be met for the optical ring
●
Configuration of a non-existent bus station with the highest possible bus address.
●
Increase of the retry value to a minimum of 3.
●
Check slot time and set to a minimum of 900.
●
Calculation of run times within the ring:
T
ring
= (n – 1) * T
FO coupler
+ L * t
FO
T
ring
Max. run time within the ring
10
Network topologies
