ABB AC 800M

Section 3 Fieldbus Topologies Optical link modules and AC 800M in a ring topology
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Optical link modules and AC 800M in a ring topology
In comparison to the single-fiber ring, an optical double ring offers greater operating
safety. The failure of a fibre optical cable or an optical interface has no effect on the
availability of the network since the flow of data in both directions runs through the
ring.
Optical ring and line redundancy can be used together in a mixed configuration as
shown in Figure 32, Redundant optical ring. The line redundant interfaces of
CI854A, RLM01, etc. can be connected to the ring by connecting each line to a
separate optical link module.
It is also possible to configure the master and slave redundancy as an option. The
figure shows both CI854A and CI840 in a redundant configuration. If they are used
in a non redundant configuration it has to be taken into account, that the disturbance
of one optical link module can cause a failure of the connected module.
The optical ring in combination with the line redundancy can only be set up by
using the optical link module “OZD Profi 12M” from Hirschmann. Other optical
link modules will get collisions of data frames that results in a complete disturbed
communication on the PROFIBUS.