ST750 GENERAL HANDBOOK
667/HB/33750/000 Page 17 Issue 6
processing provides additional safety features, as each processor continually
monitors the actions of the other, and independently turns off the lights to the
motorists and pedestrians if either processor causes an error.
The software is written in a powerful high level language that allows the
implementation of the ST750’s extensive facilities. The ST750 offers both Single
and Dual Pedestrian operation and up to a 6 Phase Traffic Controller operation,
each with solid state switching.
The power/phase assembly with its associated ST750 Phase Drive PCB and PSU
can drive up to 18 signal outputs with 230V at 4A. The pedestrian signals are
configurable to supply either 230V or 48V. Each of the two pedestrian streams has
current monitoring on two separate vehicle approaches for Red, Amber and Green
lamps plus one unmonitored approach Red lamp only. This provides TR2500A
compatible Red lamp monitoring for the Red lamps and lamp monitoring for the
Amber and Green lamps.
Note that a new ST750LED Phase Driver PCB provides lower current outputs, and
can monitor Helios LV CLS (NLM) signals. See 667/HB/32921/007 in Section 1.3.2
for further details.
The controller conforms to the UK Highways Agency specification TR2500A.
2.1.1 Single Pedestrian Controller
The ST750 Single Pedestrian Controller consists of one vehicle phase and one
pedestrian phase with a minimal set of I/O to perform all the functions of 2 phase
Pelican, Puffin or Toucan. These consist of 32 buffered inputs, 8 isolated relay
outputs, 2 Audible outputs and 1 Tactile Interlock output.
2.1.2 Dual Pedestrian Controller
The ST750 Dual Pedestrian Controller consists of 2 vehicle phases and 2
pedestrian phases with a minimal set of I/O to perform all the functions of 4 phase
Pelican, Puffin or Toucan. These consist of 32 buffered inputs, 8 isolated relay
outputs, 4 Audible outputs and 2 Tactile Interlock outputs.
2.1.3 Small Non-UK Controller
The ST750 Small Non-UK Controller consists of a 6 Phase Traffic Intersection
Controller. It is similar to the Pedestrian controllers, except in the following areas:
• It has 6 Phases
• It has no built in current lamp monitoring facilities
• It cannot be configured to output 48V from any of its Phase Drive
outputs.
2.1.4 Controller Expansion
Expansion may be achieved by adding combinations of the following equipment:
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