Specifications

ST900 Family General Handbook
667/HB/32900/000 Issue 11 Page 160 of 265
expire. During the move to the called stage, any active inter-green / all-red
extensions are implemented.
With the hurry call stage active, the condition is held for a pre-set period, the hurry
call hold period (HHC), irrespective of the condition of the minimum, extension and
maximum green timers for phases in the stage. At the end of the hold period, the
controller returns to a lower priority mode. Caution: Hurry call mode must be
allocated a higher priority than VA.
Note that if the movement is cut short by a higher priority mode, the hurry call
request remains active and is serviced after the higher priority mode unless, in the
course of operating in the higher priority mode, the cancel input is activated (see
section 17.3).
The hurry call prevent time (PHC) allows programming of the minimum period
between repeats of the same call. With the prevent timer for a call running, incoming
calls are rejected. The ‘PHC prevent time’ starts at the same time as the ‘HHC hold
time’.
17.3 Additional Facilities
The following additional facilities can be configured using Special Conditioning:
a) Hurry call request watchdog
: a request for a hurry call unit persisting for
longer than the request watchdog period will cause hurry call mode to be
unavailable and an entry made in the fault log. Hurry call mode will be
unavailable until hurry call fault log entries are cleared.
b) Hurry call watchdog: a period for which the controller may remain in a hurry
call mode. If the controller remains in hurry call mode for longer than the
watchdog period, the hurry call mode will become unavailable and an entry
made in the fault log. Hurry call will be unavailable until hurry call fault log
entries are cleared.
c) Cancel input: a separate input can be configured to cancel the hurry call. If
the cancel input becomes active during the hold period, the controller will
drop out of hurry call mode. If the cancel input becomes active during the
hold period, the prevent timer is also reset, thus the same hurry call can
cause hurry mode to become active again immediately, without waiting for a
prevent time to expire. However, if a ‘prevent time’ is still required, this may
be implemented in special conditioning.
d) Hurry call ‘call/cancel’ facility: when the hurry call input goes inactive, this is
taken by special conditioning to be a cancel signal and the special
conditioning then sets the cancel input for the hurry call ‘true’.
e) Acknowledge/Confirm output: An output can be configured to confirm that a
valid hurry call request has been received and accepted. If the request were
not accepted due to any of the reasons mentioned in section 17.2, the output
would not become active. This output may be used to activate a switching
mechanism which illuminates an indicator at the origin of the hurry call