Specifications

ST900 Family General Handbook
667/HB/32900/000 Issue 12 Page 27 of 265
2.9 Intelligent Detector Backplane
The Intelligent Detector Backplane provides an interface for up to 4 Loop Detector
Cards, each Loop Detector Card connecting to up to 4 loops.
The Intelligent Detector Backplane connects to the PHS or previous Intelligent
Detector Backplane via a high-speed serial cable through which the card also
obtains its logic power supply.
Note that the Loop Detector cards themselves are powered from a separate supply
– see section 2.11.4. The Loop Detector supply is cabled separately and is normally
24V AC from a separate transformer.
A twisted ribbon cable provides the connection between the loop detector cards and
the road loops, via the loop termination card.