Compute/Math Instructions
The compute/math instructions evaluate arithmetic operations using an expression or a specific arithmetic instruction.
Available Instructions
Ladder Diagram
Function Block Diagram
FBD Block
FBD Function
Structured Text
If you want to: | Use this instruction: |
|---|---|
evaluate an expression | CPT |
add two values | ADD |
subtract two values | SUB |
multiply two values | MUL |
divide two values | DIV |
determine the remainder after one value is divided by another | MOD |
calculate the square root of a value | SQRT |
take the opposite sign of a value | NEG |
take the absolute value of a value | ABS |
You can mix data types, but loss of accuracy and rounding error might occur and the instruction takes more time to execute. Check the S:V bit to see whether the result was truncated.
The bold data types indicate optimal data types. An instruction executes faster and requires less memory if all the operands of the instruction use the same optimal data type, typically DINT or REAL.
A compute/math instruction executes once each time the instruction is scanned as long as the rung-condition-in is true. If you want the expression evaluated only once, use any one-shot instruction to trigger the instruction.
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