CHAPTER 8: AUTOMATION AUTOMATION LOGIC
D90
PLUS
LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL 477
Table 33: Automation logic Boolean operators and latches
Boolean operators perform Boolean logic operations on any digital input or the output of
any preceding logical operator. The output of a logic operator can be used in further logic
processing. The final output of a sequence of logic operations is stored as a virtual digital
output (VDO). The logic operators available in the automation controller are tabulated as
follows.
A latch is asserted on a positive transition of its set input and retains this state until the
positive transition of its reset input. A latch accepts any digital input or the output of any
logical operator to either of its inputs. A total of 256 latches are available in the
D90
Plus
automation controller.
Figure 407: Latch used in automation logic
Automation math operators
The table outlines automation logic math syntax. Operators shown with the (a, b) suffix
operate on two operands, whereas the others operate on one operand.
Table 34: Automation math operators
Syntax Description Output is ON if...
NOT Logical NOT gate. Operates on the previous
operand.
the input is logic 0
OR(2) to OR(16) Logical OR gates. Operate on the previous 2 to 16
operands.
any input is logic 1
AND(2) to AND(16) Logical AND gates. Operate on the previous 2 to
16 operands.
all inputs are logic 1
NOR(2) to NOR(16) Logical NOR gates. Operate on the previous 2 to
16 operands.
all inputs are logic 0
NAND(2) to NAND(16) Logical NAND gates. Operate on the previous 2 to
16 operands.
any input is logic 0
XOR(2) Logical exclusive OR gate. Operates on the
previous two operands.
only one input is logic 1
LATCH (S,R) Reset-dominant latch. The operand preceding
LATCH(S,R) is the reset input. The operand
preceding the reset input is the set input.
there is a positive
transition on the set
input
Syntax Description
ABS Return the absolute value of the previous operand
ACOS Return the arccosine value of the previous operand
ADD (a, b) Add the previous 2 operands
ASIN Return the arcsine value of the previous operand
ATAN Return the arctangent value of the previous operand
ATAN2 (a, b) Return the arctangent value of the first operand divided by the second
operand, with a range of –180 to 180°
CEIL Return the smallest integer greater than or equal to the operand
COS Return the cosine value of the previous operand
DIV(a, b) Divide the first operand by the second operand
EXP Return the power of e (the base of natural logarithms) value of the previous
operand
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