Specifications

ST900 Family General Handbook
667/HB/32900/000 Issue 11 Page 197 of 265
When a stage is deleted, any demands for that stage or for phases within the stage
must also be deleted by the same timetable setting, unless the phases appear in
other stages.
In order to delete current demands and prevent further demands, it is recommended
that such demands be deleted by using special conditioning to write a “FALSE” state
to the entry in the latched or unlatched demand arrays for the appropriate
phase/stage.
When a phase is deleted, any demands for that phase must also be dependent on
the same timetable setting.
If the above two conditions are not met, outstanding demands for stages or phases
may never be satisfied.
The deletion of stages or phases is effective in all modes except Hurry Call and
Fixed Time mode, as deletion of phase/stages associated with these later two
modes would cause the controller to lock up.
If you wish to delete a phase or a stage and a form of fixed time working is required,
“Fixed time to Current Maximums” can be used. This uses the VA mode with
permanent demands and extension. Thus if a phase/stage is to be deleted, provided
demands for it are also deleted, it can be deleted without problems.
These time switch functions have been retained to allow easier upgrade of existing
configurations. Their use on new configurations is not recommended. Instead, use
Special Conditioning to modify the operation of the controller and use the timetable
function to set a conditioning flag (26.3.6).
26.3.5 Switch To/From Part-Time Mode
Part-time mode may be switched to and from by a timetable setting. See section 14
for a more detailed explanation.
26.3.6 Switch a Conditioning Flag Active/Inactive
A conditioning flag that is required to indicate a particular time of day may be
switched active or inactive by a timetable setting. Special conditioning can then read
the Flag and perform the required function(s).
26.3.7 Switched DFM Timings
DFM can be switched between four different timesets as required. The Monitor times
for each timeset can be adjusted by the Handset. See section 29.6 for more
information.
26.4 Time Switch Event Default States
Time switch Event Default State (i.e. when no time switch events are active)