Specifications

ST900 Family General Handbook
667/HB/32900/000 Issue 11 Page 229 of 265
Condition CPU Fault Action
Normal Lamp Failure
Duration is configurable by 8DF file or
handset command.
Main
Only
Fault Report only
Vehicle Red Lamp Failure
Main
Only
Actions and response times as
HA requirements for Red Lamp
Monitoring
Diagnostic Checks: Monitor Validation
(see section 33.4)
Monitoring cannot be disabled.
Main
Only
Controller Shutdown
Diagnostic Checks: Aspect Monitoring
Miscellaneous internal checks of the
controller logic, includes bus tests etc.
Monitoring cannot be disabled.
Various
Controller Shutdown
Hardware Watchdog
Hardware watchdog on Main Processor.
Cannot be disabled by configuration.
Hardware watchdogs may be provided for
other processors, but these are not required
for safe operation of the controller.
Main
Only
Controller Shutdown
Software Watchdogs
Lack of valid communications between
processors. Monitoring cannot be disabled.
Main
CPU
Controller Shutdown
Sig
Mon
Controller Shutdown
Low Lamp Supply Test (Mains)
Dim and Bright Voltage thresholds (0 to
255V), hysteresis and Durations are
configurable by handset command or 8DF
Main
Only
a) All aspects extinguished
b) All streams direct to part-time
state (Still reverts to all-off if
supply very low)
Lamp Supply out of Range (ELV)
If the lamp supply is detected outside of
bands configurable by ‘8DF’ file, all signals
are extinguished to prevent damaged and to
ensure signals are on and bright enough.
Main
Only
All aspects extinguished
Mains Missing / No ZXO Sync’
Synchronisation to the AC supply has failed,
possibly due to a mains break or excessive
noise.
Main
Only
All signals extinguished (and
POWER OFF/ON logged)
Fault “FLF 6:255 NZXO” logged if
the problem persists.