Mitsubishi Electronics FX3G User Manual
506
FX
3S
/FX
3G
/FX
3GC
/FX
3U
/FX
3UC
Series
Programming Manual - Basic & Applied Instruction Edition
18 Floating Point – FNC110 to FNC139
18.9 FNC121 – ESUB / Floating Point Subtraction
18.9
FNC121 – ESUB / Floating Point Subtraction
Outline
This instruction executes subtraction of two binary floating point data.
→ For program examples of floating point operations, refer to Section 12.10.
→ For handling of floating point, refer to Subsection 5.1.3.
→ For flag operations, refer to Subsection 6.5.2.
1. Instruction format
2. Set data
*1.
When a constant (K or H) is specified, it is automatically converted into binary floating point (real number)
when the instruction is executed.
when the instruction is executed.
3. Applicable devices
S1: This function is supported only in FX
3G
/FX
3GC
/FX
3U
/FX
3UC
PLCs.
S2: This function is supported only in FX
3U
/FX
3UC
PLCs.
Explanation of function and operation
1. 32-bit operation (DESUB and DESUBP)
Binary floating point data [
+1,
] is subtracted from binary floating point data [
+1,
], and the
subtraction result in the binary floating point format is transferred to [
+1,
].
When a constant (K or H) is specified as [
+1,
] or [
+1,
], it is automatically converted into
binary floating point.
Caution
1. When the same device is specified
The same device number can be specified in [
+1,
],[
+1,
] and [
+1,
].
In this case, note that the subtraction result changes in every operation cycle when the continuous operation type
instruction (DESUB) is used.
instruction (DESUB) is used.
Operand Type
Description
Data Type
Word device number storing binary floating point data used in subtraction
Real number (binary)
*1
Word device number storing binary floating point data used in subtraction
Data register number storing the subtraction result
Oper-
and
Type
Bit Devices
Word Devices
Others
System User
Digit Specification
System User
Special
Unit
Index
Con-
stant
stant
Real
Number
Charac-
ter String
Pointer
X Y M T C S D .b KnX KnY KnM KnS T C D
R
U \G
V Z Modify K H
E
" "
P
S1
S2
S1
S2
S1
S2
P
FNC 121
ESUB
D
−
Mnemonic
Operation Condition
16-bit Instruction
DESUB
DESUBP
Mnemonic
Operation Condition
32-bit Instruction
13 steps
Continuous
Operation
Pulse (Single)
Pulse (Single)
Operation
S
1
S
2
D
S
1
S
2
D
S
2
S
2
S
1
S
1
D
D
FNC121
DESUB
Command
input
S
1
S
2
D
[ +1, ]
− [ +1, ] → [ +1, ]
Binary floating point
Binary floating point
Binary floating point
S
1
S
1
S
2
S
2
D
D
S
1
S
1
S
2
S
2
FNC121
DESUB
Command
input
S
1
S
2
D
[ +1, ]
− [ K2346 ] → [ +1, ]
Binary floating point
Automatically
converted into binary
floating point
Binary floating point
S
1
S
1
D
D
S
1
S
1
S
2
S
2
D
D