Generic Specifications; Controller Operation - Siemens ST950 Handbook

7 G
ENERIC
7.1

Controller Operation

In common with previous controllers, the ST950 LV and ELV Controllers are phase
oriented. Timings and demands are associated with phases and the control philosophy
is designed to give right-of-way to phases in an optimum manner.
It is necessary to group phases into stages for Manual Control, operation in Urban
Traffic Control Schemes and in Cable-less Linking Schemes. The traffic requirements
and safety constraints also condition the grouping of phases into stages.
The controller receives requests for ROW from the following:
a) 'On-street' detection equipment and pedestrian push-buttons
b) The UTC computer
c) Internal MOVA7 Force Bits
d) The Cable-less Linking Facility (CLF)
e) Manual inputs
f) Special requests, e.g. hurry calls
The controller then orders the appearance of phases in accordance with the controller
strategy, the current mode operative and the demand requests for ROW. The controller
will always change stage cyclically.
The Controller facilities are described in detail in the ST950 Facilities Handbook
667/HB/46000/001.
7.1.1 Timings
All controller timings are provided in the IC4 Configuration file. These timings are
subsequently transferred to RAM and FLASH memory during controller initialisation;
the FLASH memory preserves the values over power failures.
Once in memory most controller timings can be varied by handset mnemonics or by
using the web user interface. Once the data has been loaded from the IC4
Configuration this action cannot be repeated using the same IC4 Configuration file.
This prevents the accidental overwriting of any configuration data that may have been
set up using the handset.
In the UK some timings considered to be fixed timings cannot be changed by handset,
these are typically the Amber Leaving and Red/Amber Starting periods. These timings
can, however, be specified as alterable at configuration time to suit other signal
sequences, non UK requirements etc.
Some controller timings are considered to be safety timings and can only be changed
by a person at the controller, e.g. minimum green, inter-greens and blackout timings.
These require the operator to press the 'level 3' access button on the front of the main
Security classification
Version
Last Editor
Document Name
Copyright © Siemens plc 2015. All Rights Reserved.
S
PECIFICATIONS
Unrestricted
4
Paul Cox
ST950 General Handbook
Mobility Division, Traffic Solutions
Sopers Lane, Poole, Dorset, BH17 7ER
Page 74 of 107
Status Issued
Date 16-Jul-2015
Document No. 667/HB/46000/000
Mobility is a division of Siemens Plc