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E. Role switches are allowed on both units.
Primary Unit | Secondary Unit | ||
Backup | Active (see NOTE below) | ||
RUN/ENABLED | RUN/ENABLED | ||
X OK | X OK | ||
X | LOC_RDY | X | LOC_RDY |
| LOC_ACT | X | LOC_ACT |
X | REM_RDY | X | REM_RDY |
X | REM_ACT |
| REM_ACT |
F.Role switches are not allowed on either unit.
Primary Unit | Secondary Unit | ||
Backup | Active (see NOTE below) | ||
RUN/DISABLED | RUN/ENABLED | ||
X OK | X OK | ||
| LOC_RDY | X | LOC_RDY |
| LOC_ACT | X | LOC_ACT |
X | REM_RDY |
| REM_RDY |
X | REM_ACT |
| REM_ACT |
G. Role switches allowed on both units.
Primary Unit | Secondary Unit |
Backup | Active (see NOTE below) |
RUN/DISABLED | RUN/DISABLED |
X OK | X OK |
LOC_RDY | LOC_RDY |
LOC_ACT | X LOC_ACT |
REM_RDY | REM_RDY |
X REM_ACT | REM_ACT |
H.The following situation is not valid. If detected, the units will switch roles automatically and behave as in (C) above.
Primary Unit | Secondary Unit |
Backup | Active (see NOTE below) |
RUN/ENABLED | RUN/DISABLED |
Note
* Secondary unit active is not a recommended mode of operation.
Configuration of Fault Actions
With the Redundancy CPU, you cannot select to configure certain faults to be FATAL (causing the CPU to STOP). Whenever the system is in redundancy mode with a backup unit available, the decision as to which faults are FATAL and therefore will cause a switch to the backup CPU are made by the operating system and are not configurable.
Chapter 4 Operation | 67 |