R.3.29
Date Code 20111215 Reference Manual SEL-421 Relay
SELOGIC Control Equation Programming
SELOGIC Control Equation Operators
The argument of an F_TRIG statement must be a single bit within the
SEL-421. An example of the relay detecting a falling edge of a calculated
quantity is shown in Example 3.12.
EXAMPLE 3.12 F_TRIG Operation
The SEL
OGIC control equation below shows an invalid use of the
F_TRIG operation.
ASV015 := F_TRIG (ASV001 AND ALT11) # Invalid statement, do not use
Use a SELOGIC control equation variable to calculate the quantity and
then use the F_TRIG operation on the result, as shown below.
ASV014 := ASV001 AND ALT11 # Calculate quantity in an intermediate result
variable
ASV015 := F_TRIG ASV14 # Perform an F_TRIG on the quantity
Comparison
Comparison is a mathematical operation that compares two numerical values
with a result of logical 0 or logical 1. AND and OR operators compare
Boolean values; comparison functions compare floating-point values such as
currents and other quantities. Comparisons and truth tables for operation of
comparison functions are shown in Table 3.25.
Math Operators
Use math operators when writing math SELOGIC control equations. Math
SEL
OGIC control equations manipulate numerical values and provide a
numerical base 10 result. Table 3.26 summarizes the operators available for
math SEL
OGIC control equations.
Table 3.25 Comparison Operations
A B A>B A>=B A=B A<>B A<=B A<B
6.357.00000111
5.105.10011010
4.254.00110100
Table 3.26 Math Operator Summary
Operator Description
( ) Parentheses
+, –, *, / Arithmetic
SQRT Square root
LN, EXP, LOG Natural logarithm, exponentiation of e, base 10 logarithm
COS, SIN, ACOS, ASIN Cosine, sine, arc cosine, arc sine
ABS Absolute value
CEIL Rounds to the nearest integer towards infinity
FLOOR Rounds to the nearest integer towards minus infinity
– Negation
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