Specifications

ST900 Family General Handbook
667/HB/32900/000 Issue 11 Page 133 of 265
When part-time mode is no longer requested, i.e. when it is time for the controller to
switch back on, the controller enters start-up mode to ensure normal operations
resume in a safe manner, see section 13.
14.3 Part-Time Mode Parallel Stage Streaming Facilities
Part-time mode can be active on any or all of the streams. Those streams not in
part-time mode will continue to run a lower priority mode.
If some streams are required to enter part-time mode while some are not, special
conditioning must be used to either disable part-time mode on particular streams or
only request part-time mode on certain streams.
Each stream requested to switch off will then independently move to its configured
switch off stage as normal (see section 14.2). However, only when all the streams
requested to enter part-time mode have reached their switch off stages and all their
minimum greens have expired, will all the signals on those streams be sent to their
configured part-time state. This ensures that all of the streams switch off at the same
time, not when each reaches its own switch off stage.
The part-time switch off stage for each stream is specified in configuration, as is the
part-time signal state and the lamp sequences to and from the part-time state.
If red lamp monitoring is configured, consideration also needs to be given as to
whether additional streams need to be extinguished when a second red lamp fault is
confirmed, see section 38.2.3.
14.4 ‘Fail to Part-Time’ State
This configuration option is available primarily for multi-stream non UK controllers. It
allows the controller to immediately switch a stream directly into its part-time state
(which could be configured as blackout or flashing vehicle ambers for example)
when a fault is confirmed on that stream. Note that this facility can be enabled even
if part-time mode is not required, i.e. even if the controller is not required to enter
part-time by time of day.
Correspondence faults (section 33) will cause the stream(s) on which the faults exist
to immediately enter their part-time state, while other streams continue to cycle
normally. Once in this state, further faults on reds and ambers can be configured to
be ignored, but faults with greens will always cause the whole controller to shut
down, removing the lamp supply. If hardware fail flash is configured (section 34), all
streams will enter their hardware flash state.
Second red lamp failures can also be configured to cause streams to enter their
part-time flashing state, see section 38.2.3.