Chapter 6
Compute/Math Instructions (CPT, ADD, SUB, MUL, DIV, MOD, SQR, SQRT, NEG, ABS)
Input Parameter
Data Type
EnableIn
BOOL
Source A
REAL
Source B
REAL
Output Parameter
Data Type
EnableOut
BOOL
Dest
REAL
Description:
If source B is zero and
All operands are integers (SINT, INT, or
DINT)
At least one operand is a REAL
280
FBD_MATH Structure
Description
Enable input. If cleared, the instruction does not execute and outputs are not updated.
Default is set.
Value of the dividend.
Valid = any float
Value of the divisor.
Valid = any float
Description
The instruction produced a valid result.
Result of the math instruction. Arithmetic status flags are set for this output.
If Source B (the divisor) is zero, the following happens:
• A minor fault occurs:
– Type 4: program fault
– Code 4: arithmetic overflow
• The destination is set as follows.
And the destination is a
SINT, INT, or DINT
REAL
The MOD instruction does not capture an overflow that may have
IMPORTANT
occurred during the calculation. If an overflow occurs, a minor fault will
be generated, but the S:V bit will not be set.
Rockwell Automation Publication 1756-RM003N-EN-P - October 2011
And the result is
Then the destination is set to
Source A
Positive
-1
The S:N and S:Z flags are not set.
Negative
0
Positive
1.$ (positive infinity)
Negative
-1.$ (negative infinity)