Specifications

ST900 Family General Handbook
667/HB/32900/000 Issue 10 Page 91 of 265
The timing range is 0 to 199 seconds in 1-second steps with one time and minimum
range limit for each phase-to-phase transition.
See section 6.11 for information on the inter-greens to and from pedestrian phases.
6.5.8 Starting Inter-green (IGS)
The starting inter-green period is a safety period in Start-up Mode before any
phases gain ROW – see section 13.
The timing range is 0 to 255 seconds in 1-second steps with one time for the whole
controller.
6.5.9 Conditioning Timers (PIR, CDT)
Up to 96 conditioning timers (0 to 95) are available for use as auxiliary timers.
The uses of the conditioning timers include the following:
(a) Holding a stage for a specified fixed period when no phases gain ROW,
e.g. the all-red stage. Normally dummy phases are used for this purpose,
but this method may be used if no dummy phases are available.
(b) Timing long periods - can be achieved by running the same timer several
times, e.g. to time 20 minutes, give the timer a value of 20 and run it 60
times.
(c) Switched window timers.
(d) Limit Green watchdog timer.
(e) Hurry Call watchdog timer.
The timing range for each timer can be configured as either 0 to 255 seconds in 1-
second steps or 0.0 to 31.8 in 0.2 second steps. As range checks are now applied
on the handset commands, the values need no longer be range checked in special
conditioning before they are used.
6.5.10 Limit Green Watchdog
(Facility constructed in Special Conditioning for Non UK Only)
In all modes except Hurry Call, Vehicle Actuated and Manual Control, the maximum
duration of each stage green can be governed by a limit green watchdog time. One
limit green watchdog timer (a Special Conditioning timer) is provided, which is
applied to each stage in turn.
The stage limit green watchdog timer commences timing when the stage green is
reached and is reset on a plan change, a mode change and when the stage
terminates.