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Maintenance
180
840 USE 106 00 January 2003
Verifying Health of a Hot Standby System
Health Messages The Hot Standby modules exchange a health message approximately every 10 ms.
If the Primary has an error, the Standby is notified and assumes the Primary role. If
the Standby has an error, the Primary continues to operate as a standalone.
The RIO head processors also verify communication with one another periodically.
Automatic
Confidence
Tests
The system automatically performs two kinds of confidence tests on the Hot Standby
modules:
Startup tests
Run time tests
Startup Tests The system performs four startup tests:
Prom checksum
RAM data test
RAM address test
Dual port RAM test
If the module fails any of these tests, it remains offline and does not communicate
with the other Hot Standby module. To retest the system, the power must be turned
off and on again.
Run Time Tests These tests are performed whenever the Ready indicator is on. They are executed
in small groups to prevent delays in scan time.
The system performs three kinds of run time confidence tests:
Prom checksum
RAM data test
RAM address test