Schweitzer Engineering Laboratories SEL-734 - Table 8.2 Operator Precedence

8.10
SEL-734 Meter Instruction Manual Date Code 20090730
Logic
SEL
OGIC Control Equation Variables/Timers
SELOGIC Control
Equation Operators
Use the analog comparators to create a Boolean result from an analog value
(see Appendix H: Analog Quantities), and 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. Table 8.2 contains a summary of operators available in the
SEL-734.
Operator Precedence
When you combine several operators and operands within a single expression,
the SEL-734 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 meter evaluates the NOT operation of SV04 first
and uses the result in subsequent evaluation of the expression. Operator
precedence is shown in Table 8.2.
Timers Reset When
Power Is Lost or
Settings Are Changed
If power is lost to the meter or if settings change, the SELOGIC control
equation variables/timers reset. Meter Word bits SVn and SVnT (n = 01
through 16) reset to logical 0 after power restoration or a settings change.
Figure 8.11 shows an effective seal-in logic circuit, created by use of Meter
Word bit SV07 (SEL
OGIC control equation variable SV07) in SELOGIC
control equation SV07 (see SEL
OGIC Control Equation Variable Timer Input
Equations on page SET.4 of the SEL-734 Settings Sheets):
SV07 = (SV07 OR OUT101) AND (OUT102 OR OUT401)
Figure 8.11 Example Use of SELOGIC Variables/Timers
Table 8.2 Operator Precedence
Operator Description
( ) Parenthesis
NOT Boolean Complement
R_TRIG Rising Edge Trigger
F_TRIG Falling Edge Trigger
<, >, <=, >= Analog Comparison
= Analog Equality Check
<> Analog Inequality Check
AND Boolean AND
OR Boolean OR
SV06PU
SV06D0
SV07PU
SV07D0
SV06
SV07
OUT101
OUT102
OUT103
OUT401
OUT101
OUT102
OUT401
Courtesy of NationalSwitchgear.com