Specifications

RailCorp Engineering Manual — Signals — Equipment Manual
Cerberus Level Crossing Monitor Field Equipment Manual TMG E1261
6.1.2.7.4 Combinations of logic Operations
The logical operators AND, OR, and NOT can be combined using brackets [, and ] to
form any required Boolean expression.
An example of a combinational logical operations is:
Either as relay logic by:
or as a Boolean expression
D = [!A + B] & C
D will be true when C is true and [ A is not true or B is true].
6.1.2.8 Steady result expression
Intermediate variables and Output variable are controlled by steady result expressions.
These variables become TRUE (or ON) when the steady result expression controlling the
variable becomes TRUE. The variables become FALSE (or OFF) when the steady result
expression controlling the variable becomes FALSE.
Steady result expressions have the following format:
x = y
where
x is variable which was declared in the IO list as either an Intermediate or an Output.
= identifies the expression as being a steady result type of expression.
y is a Boolean expression as described previously.
6.1.2.9 Timer expression
A timer variable becomes TRUE when the expression that drives the timer has been
TRUE for the length of time that the timer is set for. The timer variable becomes FALSE
immediately that its expression becomes FALSE.
Timer expressions have the following format:
x =T Ah Bm Cs y
where
© RailCorp Page 68 of 89
Issued August 2012 UNCONTROLLED WHEN PRINTED Version 2.1