Proceedings 2002/2003 - IRSE

86
INTERNATIONAL CONVENTION
Interior of ‘Cereberus’ monitor – data acquisition
board at left, power supply and surge filters on right
to crossing control equipment by means of a variety
of purpose-designed interface modules.
Communication with the Control Centre is by
PSTN dial-up telephone line or, in some areas not
served by landline, by GSM cellular phone connections.
The unit monitors the status of the crossing
equipment, logs events, reports warning or failure
conditions to the central location, and provides the
facility for remotely testing the level crossing battery
supply and the monitor itself.
The Central Monitoring and Control Workstation is
the other half of the ‘Cerberus’ system, linked to a
network of up to 100 level crossings. The workstation
is a standard desktop computer, with two
dial-up modem connections on separate Telstra
phone lines, one each for incoming and outgoing
calls. Located at an operations control centre that is
manned 24 hours a day, the workstation receives
incoming status and alarm calls from its network of
‘Cerberus’ monitors, displays the status of all crossings
on the network and carries out a remote test of
every crossing in each 24-hour cycle. It communicates
with every crossing at least once every 12
hours to check the communications line. All tests,
status reports and alarm messages are logged to
hard disk.
Integral to the ‘Cerberus’ system are the customdesigned
‘Cerberus’ software products – the
monitor firmware, the central office software, and the
engineer's software package. The communications,
logging, test and operator interface software is a
Windows application developed in-house, using ‘C’
Cerberus Control Centre Workstation
and Visual Basic.
FEATURES OF THE ‘CERBERUS’
SYSTEM
The ‘Cerberus’ monitor unit monitors the status of
the crossing equipment, logs events, reports
warning or failure conditions to the central location,
and provides the facility for remotely testing the level
crossing battery supply and the monitor itself. It is
designed to minimise the risk of it providing
incorrect information in a manner that is not
obviously incorrect, or of reducing the integrity of the
level crossing protection. It is equipped with two
serial data ports, one for interrogation at site by
means of a portable personal computer, and the
second port for a dial-up modem for communication
over a Telecom line, to the central control system.
The Level Crossing monitor continually examines
the status and relationship of the various inputs and
outputs. The monitor detects changes in its
analogue inputs, digital inputs and its own digital
outputs.
EVENT LOGGING CAPACITY
Details of these changes are stored with their date
and time of occurrence (to one-tenth of second). At
least the last 9,000 changes are stored, with the
oldest event is automatically replaced by the next
new event when the event log is full.
The log is maintained in a non-volatile RAM that
has an integral lithium battery with a life of 10 years.
The memory devices have been successfully
recovered after an accident in which the crossing
equipment hut was destroyed, and the monitor unit