4.84
SEL-751A Relay Instruction Manual Date Code 20100129
Protection and Logic Functions
Logic Settings (SET L Command)
SELOGIC Control
Equation Operators
Use the Boolean operators to combine values with a resulting Boolean value.
Edge trigger operators provide a pulse output. Combine the operators and
operands to form statements that evaluate complex logic. SEL
OGIC control
equations are either Boolean type or math type. Because the equals sign (=) is
already used as an equality comparison, both Boolean type and math type of
SEL
OGIC control equation settings begin with an “assignment” operator (:=)
instead of with an equals sign.
Boolean SEL
OGIC control equation settings use logic similar to Boolean
algebra logic, combining Relay Word bits together with one or more of the
Boolean operators listed in Table 4.33. Math SEL
OGIC control equation
settings operate on numerical values, using one or more of the Mathematical
operators listed in Ta ble 4 . 33. These numerical values can be mathematical
variables or actual real numbers.
The executed result of a math SEL
OGIC control equation is stored in a math
variable. The smallest and largest values a math variable can represent are
–16777215.99 and +16777215.99, respectively. If the executed result exceeds
these limits, it will be clipped at the limit value. For example, when the
MV01:= executed result is –16777219.00, MV01 will be –16777215.99.
Similarly, when the MV02 := executed result is +16777238.00, MV02 will be
+16777215.99.
Comments can be added to both boolean and math SEL
OGIC control equations
by inserting a # symbol. Everything following the # symbol in a SEL
OGIC
control equation is treated as a comment. See Table 4. 34 for this and other
Boolean and math operators and values.
Operator Precedence
When you combine several operators and operands within a single expression,
the SEL-751A evaluates the operators from left to right, starting with the
highest precedence operators and working down to the lowest precedence.
This means that if you write an equation with three AND operators, for
example SV01 AND SV02 AND SV03, each AND will be evaluated from the
left to the right. If you substitute NOT SV04 for SV03 to make SV01 AND
SV02 AND NOT SV04, the device evaluates the NOT operation of SV04 first
and uses the result in subsequent evaluation of the expression.
Ta b le 4 .3 3 S EL OGIC Control Equation Operators (Listed in Operator
Precedence) (Sheet 1 of 2)
Operator Function
Function Type (Boolean
and/or Mathematical)
( )
parentheses Boolean and Mathematical
(highest precedence)
–
negation Mathematical
NOT
NOT Boolean
R_TRIG
rising-edge trigger/detect Boolean
F_TRIG
falling-edge trigger/detect Boolean
*
/
multiply
divide
Mathematical
+
-
add
subtract
Mathematical
<, >, <=, >=
comparison Boolean
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