16 'Fail To Part-Time' State; Urban Traffic Control (Utc); Priority And Emergency Vehicle Mode - Siemens ST950 Handbook

16 'F P
AIL TO
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.
This facility is sometimes referred to as 'software fail flash' as it is similar to 'hardware
fail flash', but has the advantage that the entire controller does not 'shutdown'.
Correspondence faults 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.
It should be noted that if 'Ignore Reds and Yellows during Fail to Part Time' is enabled,
Correspondence faults on the Red and Yellow outputs no longer trigger shut down and
accordingly these faults are only detected by the Primary CPU, and not the Secondary
CPU. (Faults detected by the Secondary CPU always trigger shut down)
Second Red Lamp failures or Last Lamp failures can also be configured to cause
streams to enter their part-time flashing state.
The 'Fail to Part-Time' facility does not affect Green-Green and Green-Yellow Conflict
monitoring. Conflict monitoring is always performed by both Primary and Secondary
CPUs and always requests shut down.
If hardware fail flash is configured (section 35), all streams will enter their hardware
flash state on controller shut down (failure mode).
17 U T
RBAN RAFFIC
In UTC mode, operations are controlled and monitored by the central computer of an
Urban Traffic Control system.
Stage changes are effected by the application of forces and demands. The demands
may either be local or simulated by the computer. During UTC mode maximum green
timers normally have no effect and are held in a RESET state.
Instation equipment at the central computer office communicates over an IP network to
the ST950 internal UTMC OTU.
Control signals are normally transmitted as two 8-bit control words and monitoring
signals are returned as two 8-bit reply words.
18 P
RIORITY AND
Priority and Emergency Vehicle modes provide a facility in which appropriate vehicles
have priority in gaining and holding ROW over other vehicles.
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Paul Cox
ST950 General Handbook
Mobility Division, Traffic Solutions
Sopers Lane, Poole, Dorset, BH17 7ER
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