Specifications

ST900 Family General Handbook
667/HB/32900/000 Issue 11 Page 169 of 265
The timetable settings that are programmed may be changed via the handset using
the TSW or TTB command.
If the group timings, group influences and/or timetable settings are not known at the
time that the controller is configured, they may be added at a later date using the
handset.
21.3 Group Influences
Each group influence consists of a function (listed below) and an associated stage
(or any stage within the stream). These can be accessed using the IFN and IFS
handset commands respectively:
0. GO VA - allows vehicle actuation to operate on the stream except that phase
maximums have no effect and phases may only terminate on a gap change. The
controller is still in CLF mode. This influence should not be confused with the
facility to isolate from CLF mode using a timetable setting when full VA facilities
with maximum timings will be operative.
1. IMMEDIATE MOVE - requests an immediate move to a specified stage subject to
minimum green and inter-green timings and stage to stage movement
restrictions.
2. DEMAND DEPENDENT MOVE - requests an IMMEDIATE MOVE to a specified
stage providing a demand exists for a phase within that stage.
3. HOLD - does not allow any stage change to occur in this stream. ROW will
remain on the current stage at the time of the group change. Care should be
taken if this influence follows a move that goes via an alternative stage, e.g. all-
red, as the controller could then be held in all-red.
4. PREVENT EXCEPT - prevent all moves except to a specified stage providing a
demand exists for a phase within that stage and providing no extensions exist for
terminating phases. This can used to prevent any stage changes (after a
Demand Depend Move for example) and prior to an Immediate Move event (to
the same stage specified here) to ensure that the controller is ready to action the
Immediate Move event when the plan requests it.
Functions 5 to 7 are not normally required on an ST900:
5. ADD IMMEDIATE MOVE - add an IMMEDIATE MOVE to the existing influence
so that either influence may be actioned.
6. ADD DEMAND DEPENDENT MOVE - add a DEMAND DEPENDENT MOVE to
the existing influence so that either influence may be actioned.
7. IGNORE - continue with previous influence.