Specifications

ST900 Family General Handbook
667/HB/32900/000 Issue 12 Page 19 of 265
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2.1 System Overview
The Siemens ST900 is a mains driven Traffic Controller that can be supplied either
in a single-door outer case with a 6U logic rack and equipment mounting frame or as
a free-standing logic rack housing the power supply, CPU and Lamp Switch cards.
The essential differences between the ST800 Controller and the new ST900
Controller are;
 The Main Processor Card is now coupled with a daughter card (the PHS
card) that in turn provides high-speed serial connection to new I/O cards and
new Intelligent Detector Backplanes.
 The new serial I/O cards are mounted on the rear panel of the controller
cabinet and allow direct termination of street cabling without resorting to the
use of additional terminal blocks and soft wire conversion kits. Further
information on the I/O card is in section 2.10.
 The new Intelligent Detector Backplanes are mounted in the rack. These
provide support for the connection of up to four standard Loop Detector
Cards such as Siemens ST4S. The Backplane connects to a ribbon cable
that terminates in a Loop Termination Board mounted on the cabinet rear
panel. The Loop Termination board provides the termination point for 16
Loop Feeder pairs without the use of additional terminal blocks and twisted
wire kits. Further information on the Intelligent Detector Backplanes is
available in section 2.10.
 All Loop Detector Cards are powered from a Detector Supply Transformer.
The MDU is no longer used to provide power for Loop Detector Cards.
 Each pushbutton is associated in the IC4 configuration with one specific
kerbside detector (if used), thus each pushbutton input and kerbside input
must connect to its correct pushbutton / kerbside. Pushbuttons must not be
commoned together and connected to a single input. See section 7.4 for
more information.
 Internal SDE/SA is available (and does not require the /102 PLD), with the
SDE/SA loops connected to the new Intelligent Detector Backplanes (or new
I/O cards if required).
With the new I/O cards and new Intelligent Detector Backplanes, the ST900 Family
now supports up to 248 I/O lines. The combination of the new I/O cards and new
Intelligent Detector Backplanes in the ST900 completely replaces existing I/O
previously used in the ST800. Neither the main processor card I/O nor the use of I/O
expansion cards 667/1/27003/000 is supported in the ST900.