CHAPTER 8: AUTOMATION AUTOMATION LOGIC
D90
PLUS
LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL 479
AVO1 = 20 // initialize virtual analog output 1 to 20
AVO1 + SRC4 Ig RMS = AVO3 // add an offset of 20 to the Ig RMS
Automation virtual outputs
The table outlines automation virtual output syntax.
Table 35: Automation virtual output operators
Automation comparators
Automation comparators have two inputs that are denoted "+" and "–". Each input is
assigned to a FlexAnalog value or an analog constant. There are six types of comparators
in automation logic, as follows:
• Greater than (>)
• Less than (<)
• Equal to (=)
•Not equal to (≠)
• Greater than or equal to (≥)
• Less than or equal to (≤)
The output of the comparator is logic 1 if the inputs satisfy the condition of the particular
comparator. Otherwise, the output is logic 0. The comparator output can be used as an
input to Boolean logic or be assigned to an automation virtual output (AVO).
The following automation logic uses the greater than or equal to and the less than or equal
to comparators to test that a value is within a specified range.
Figure 409: Using comparators to verify a value is within a specified range
The following automation logic uses the less than comparator to check if two values are
approximately equal.
Syntax Description
VDO(1) to VDO(96) Assigns the previous automation logic operand to the corresponding
automation virtual digital output
VAO1 to VAO64 Assigns the previous automation logic operand to the corresponding
automation virtual analog output
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