Compute and Math Instructions

The compute/math instructions evaluate arithmetic operations using an expression.

Available Instructions

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	SQR
take the opposite sign of a value	NEG
take the abosolute 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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