Omron SYSMAC CQM1H Series, Programming Manual

Page: 382 / 602

357
Floating-point Math Instructions Section 5-24
5-24-6 FLOATING-POINT SUBTRACT: –F(––)
Limitations The Minuend (Mi+1 and Mi) and Subtrahend (Su+1 and Su) data must be in
IEEE754 floating-point data format.
DM 6143 to DM 6655 cannot be used for R.
Description When the execution condition is OFF, –F(––) is not executed. When the exe-
cution condition is ON, –F(––) 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.)
If the absolute value of the result is greater than the maximum value that can
be expressed as floating-point data, the Overflow Flag (SR 25404) 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 (SR 25405) 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.
Note 1. The results could be zero (including underflows), a numeral, +
∞
, or –
∞
.
2. The Error Flag will be turned ON and the instruction won’t be executed.
Flags ER: Indirectly addressed EM/DM word is non-existent.
(Content of
*
EM/
*
DM word is not BCD, or the EM/DM area boundary
has been exceeded.)
ON if the minuend or subtrahend data is not recognized as floating-
point data.
EQ: ON if both the exponent and mantissa of the result are 0.
Mi : First minuend word
IR, SR, AR, DM, EM, HR, TIM/CNT, LR
Su : First subtrahend word
IR, SR, AR, DM, EM, HR, TIM/CNT, LR
Ladder Symbols
Operand Data Areas
R : First result word
IR, SR, AR, DM, EM, HR, LR
F(
−−
)
Mi
Su
R
@ F(
−−
)
Mi
Su
R
Minuend
Subtrahend 0 Numeral +
∞
–
∞
NaN
0 0 Numeral +
∞
–
∞
Numeral Numeral See note 1. +
∞
–
∞
+
∞
–
∞
–
∞
See note 2. –
∞
–
∞
+
∞
+
∞
+
∞
See note 2.
NaN See note 2.
R+1 R
Mi
Minuend (floating-point data, 32 bits)
Mi+1
Su
Subtrahend (floating-point data, 32 bits)
Su+1
Result (floating-point data, 32 bits)
−