Redundant Cpu - Motorola ACE3600 RTU Owner's Manual

Redundant CPU

Redundant CPU Behavior
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When redundant CPUs (ACE3680 only) are used, the CPU in the leftmost CPU slot (to the
right of the first power supply) is the primary CPU. The CPU in the rightmost CPU slot is
the secondary CPU. The primary CPU communicates with the primary power supply and
the secondary CPU communicates with the secondary power supply (if the secondary
power supply exists.)
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When the RTU is powered up, the primary CPU becomes the active CPU
(monitors/controls the I/O modules.) If the primary CPU does not exist or has failed, the
secondary CPU becomes the active CPU. If the primary exists and is working, the
secondary CPU becomes the standby CPU (which continuously monitors the active CPU.)
On the active CPU, the I1 ACTV LED is lit.
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If the standby CPU detects that the active CPU has failed, it automatically becomes the
active CPU. When the faulty CPU is repaired or replaced with a working CPU, the newly
installed CPU becomes the standby CPU.
•
If both the primary and secondary CPUs exist and are working, a forced active CPU
switchover can be performed from the STS Hardware Test by deactivating the active CPU,
after which the standby CPU will become active. A forced switch can also be performed
from a 'C' user application.
•
If both the primary and secondary CPUs exist and are working, hot swap of the CPU is
supported. Note that if the active CPU is removed, the standby CPU automatically
Figure E-1 ACE3600 Redundant CPU and Power Supply Configuration
Appendix E: CPU and Power Supply Redundancy
E-2