Specifications

ST900 Family General Handbook
667/HB/32900/000 Issue 11 Page 201 of 265
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27.1 Repeat Pulses
The Siemens Type 900 Controller may be linked to other traffic controllers so that a
pulse which occurs, or a pulse which is created by a condition occurring, in one
controller may be repeated to the other. The function of the pulse when received will
depend on the method of control of the intersection.
One function of the facility is to maintain traffic flow through closely associated
intersections. When a certain phase gains ROW, a pulse is transmitted to the linked
controller to demand a phase along the same route.
Special conditioning is used to provide an output from the controller under pre-
defined conditions, e.g. during Red/amber or amber leaving of a particular phase.
27.2 OTU Linking
The Siemens Type 900 Controller may be linked to other controllers in a UTC
scheme when it is required to share an outstation transmission unit (OTU) between
more than one controller. In this case the link will only be for connection between
the OTU and the other controllers. The operation of the controller will have no effect
on the link.
27.3 Local Linking
Input
Bit
Local Link Bit Description Configuration
PV1 PV1 is normally held active to
prevent the pedestrian phase and
the release of PV1 is only actioned
after a configurable delay period.
A pedestrian demand is serviced
while PV1 is inactive and the delay
has expired or within a window
time after the delay has expired.
The vehicle phase extensions are
inhibited during the window time.
A short release pulse (< 300mS)
on PV1 does not restart the delay
or window timers but does start the
link fail timers.
PV1 input line allocation.
Link delay time (LKD)
Link window time (LKW)
Link mode - resetting mode & override
timer start mode (LKM)
Link override time (LKO)
Link active fail time (LKA)
Link in-active fail time (LKI)
NB: LKA and LKI are no longer
required by TR2500 but the facility has
been retained in the firmware.
LD Local link pedestrian demand Special conditioning inserts a latched
or unlatched demand for the
pedestrian as required.