Omron SYSMAC CJ - REFERENCE MANUAL 08-2008 Reference Manual page 644

Floating-point Math Instructions
Description
Note
Flags
Precautions
604
–F(455) subtracts the 32-bit floating-point number in Su+1 and Su from the
32-bit floating-point number in Mi+1 and Mi and places the result in R+1 and
R. (The floating point data must be in IEEE754 format.)
Mi+1
– Su+1
R+1
If the absolute value of the result is greater than the maximum value that can
be expressed as floating-point data, the Overflow Flag will turn ON and the
result will be output as
If the absolute value of the result is less than the minimum value that can be
expressed as floating-point data, the Underflow Flag will turn ON and the
result will be output as 0.
The various combinations of minuend and subtrahend data will produce the
results shown in the following table.
Subtrahend 0
0 0
Numeral Numeral
+ –
(See note 2.)
– +
NaN
1. The results could be zero (including underflows), a numeral, + , or – .
2. With CJ1H-CPU@@H-R CPU Units, an undetermined value will be output.
3. The Error Flag will be turned ON and the instruction will not be executed.
Name Label
Error Flag ER
Equals Flag =
Overflow Flag OF
Underflow Flag UF
Negative Flag N
The Minuend (Mi+1 and Mi) and Subtrahend (Su+1 and Su) data must be in
IEEE754 floating-point data format.
Minuend (floating-point data, 32 bits)
Mi
Su
Subtrahend (floating-point data, 32 bits)
Result (floating-point data, 32 bits)
R
.
Minuend
Numeral +
Numeral +
See note 1. +
(See note 2.)
– See note 3.
(See note 2.)
+ +
Operation
ON if the minuend or subtrahend data is not recognized
as floating-point data.
ON if the minuend or subtrahend is not a number (NaN).
ON if + is subtracted from + .
ON if – is subtracted from – .
OFF in all other cases.
ON if both the exponent and mantissa of the result are 0.
OFF in all other cases.
ON if the absolute value of the result is too large to be
expressed as a 32-bit floating-point value.
ON if the absolute value of the result is too small to be
expressed as a 32-bit floating-point value.
ON if the result is negative.
OFF in all other cases.
Section 3-15
– NaN
–
–
(See note 2.)
–
See note 3.
See note 3.