Specifications

ST900 Family General Handbook
667/HB/32900/000 Issue 11 Page 162 of 265
Note: If the Hurry Call is inserted from a momentary push-button it is advisable to
use a Hurry Call Confirm output in the above instances, so that the sender knows if
the Hurry Call has been accepted.
17.6 Control from a Remote Push-Button
If, on pressing the hurry request button, the confirm indication does not illuminate,
then this indicates that the request has been rejected due to either:
i) The controller is in a higher priority mode,
ii) The prevent timer being active,
iii) The delay timer for a higher priority hurry call being active (see section 17.5),
iv) The prevent timer on another hurry call unit is active (see section 17.5).
v) Hurry Call mode being disabled (see section 17.3 for some examples).
The fact that the HURRY ACTIVE indicator is illuminated following the request only
indicates that the hurry request has been accepted and latched into the controller.
The servicing of the request may be delayed because a higher priority mode is
active or a higher priority hurry call is requested.
In the case where UTC mode is a higher priority than the Hurry Call mode, on
receipt of a valid hurry call request, the confirm indication will normally be
transmitted to the central office for action. The central office would then either
relinquish UTC control (allowing the controller to service the request) or by
introducing a special hurry call plan under UTC control itself.
17.7 Control from a Queue Detector
Normally, the signal for the queue detector is processed by a call/cancel facility.
While the output of the call/cancel is active it may be required to force and hold the
hurry call stage indefinitely. To achieve this, the prevent period is set to zero and
the hold period is set at some small value, say five seconds. When the hold period
expires, the hurry call stage is immediately requested.
When the hurry call request from the call/cancel facility goes inactive, this is taken
as a cancel request and the hurry call stage is terminated. (This requires special
conditioning.)
The hurry call may be interrupted by a higher priority mode and on terminating this
mode the hurry call is serviced again only if it is still requested.
17.8 Timings Range
The range of timings for the DHC Delay, HHC Hold and PHC Prevent periods is 0 to
255 seconds in 1-second steps.