Sel SEL-421 - Parentheses; Boolean Operator Summary; Parentheses Operation in Boolean Equation

R.3.26
SEL-421 Relay Reference Manual Date Code 20111215
SELOGIC Control Equation Programming
SELOGIC Control Equation Operators
Parentheses
Use paired parentheses to control the execution order of operations in a
SEL
OGIC control equation. Use as many as 14 nested sets of parentheses in
each SEL
OGIC control equation. The relay calculates the result of the
operation on the innermost pair of parentheses first and then uses this result
with the remaining operations. Table 3.21 is a truth table for an example
operation that illustrates how parentheses can affect equation evaluation.
– Subtract
<, >, <=, >= Comparison
= Equality
<> Inequality
AND Boolean AND
OR Boolean OR
Table 3.20 Boolean Operator Summary
Operator Description
( ) Parentheses
NOT Logical inverse
AND Logical AND
OR Logical OR
R_TRIG Rising-edge trigger
F_TRIG Falling-edge trigger
>, <, =, <=, >=, <> Comparison of values
Table 3.19 Operator Precedence from Highest to Lowest (Sheet 2 of 2)
Operator Description
Table 3.21 Parentheses Operation in Boolean Equation
A B C
A AND B
OR C
A AND
(B OR C)
00000
00110
01000
01110
10000
10111
11011
11111