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4 USER GUIDE
4.5 Failures and Avoidance
When both the primary ring and secondary ring are communicating normally, each OD.RING
module uses primary ring data, not secondary ring data.
Figure 4-5 Data Flow in Normal Operation of Primary Ring and Secondary Ring
The OD.RING modules use only primary ring data or secondary ring data. Whether they use
primary ring data or secondary ring data depends on how data is received.
When one module is receiving data normally from another via both the primary ring and
secondary ring, the primary ring data is used. Primary ring data has priority over secondary ring
data.
When one module is receiving data normally from another via the primary ring, the primary ring
data is used.
When one module is receiving data normally from another via the secondary ring, the secondary
ring data is used.
Even if a failure occurs, the OD.RING modules can automatically avoid this to continue
communication normally. Examples of failures and their avoidance are given below.
Secondary ring
A
Primary ring
D
A through D are OD.RING modules.
4-6
B
C
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