
8.11
Date Code 20090730
Instruction Manual
SEL-734 Meter
Logic
Math Variables
Math Variables
Sixteen SEL
OGIC
control equation math variables are available. SEL
OGIC
control equation math variables are math calculation storage results. Use the
MAT
command to view the results of each math variable.
Use math variables in fixed-form programming to store the results of math
calculations as arguments in math calculations and comparisons. Available
math operators are plus (+), minus (–), multiply (*), and divide (\).
illustrates SEL
OGIC
control equation math variable usage.
Math variable analog quantities use secondary values
EXAMPLE 8.1
SEL
OGIC
Control Equation Math Variables
The equations below show fixed-form SEL
OGIC
control equation
programming examples that use SEL
OGIC
control equation math
variables. Each line has a comment after the # that provides
additional description.
MV01 :=
378.62
# Store 387.62 in MV01
MV09 :=
5 + VA_MAG
# Store sum of 5 and A-phase secondary
voltage in MV09
Math Error Detection
If a math operation results in an error, the SEL-734 turns on the math error bit,
MATHERR, in the Meter Word. A settings change or the
STATUS SC
command provides reset for this bit. For example, if you attempt to divide a
value by zero, the math error bit will be asserted until you clear the bit with a
STATUS SC
command or change settings.
Counter Variables
SEL
OGIC
control equation counters are up- or down-counting elements, with a
reset input and two outputs:
➤
one asserts when the programmable count limit is reached
➤
the other asserts when the counter is at position zero
These counter elements conform to the standard counter function block #3 in
IEC 1131-3 First Edition 1993-03 International Standard for Programmable
Controllers - Part 3: Programming Languages.
describes the Boolean input settings, counter value setting, and
Boolean outputs of the counters. Note that
n
= 01 to 16.
Table 8.3
Counter Inputs and Outputs
(Sheet 1 of 2)
Name
Type
Description
SC
n
LD
Load Preset Value
Loads SC
n
, with SC
n
PV. This will assert SC
n
QU.
SC
n
PV
Maximum Value
Maximum number of counts that SC
n
will increment
before freezing.
SC
n
CU
Count Up on Rising
Edge
Value that increments SC
n
up. Use any SEL
OGIC
con-
trol equation setting or Meter Word bit.
SC
n
CD
Count Down on
Rising Edge
Value that increments SC
n
down. Use any SEL
OGIC
control equation setting or Meter Word bit.
SC
n
R
Counter Reset
Logic that resets counter output value, SC
n
, to zero.
Содержание SEL-734
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