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FX3G/FX3U/FX3UC Series Programmable Controllers
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.
3. Applicable devices
S: This function is supported only in FX3U/FX3UC 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 a same device is specified
A 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.
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
Real
Number
Charac-
ter String
Pointer
XYMTCSD.b KnX KnY KnM KnS T C D R U\G VZModifyKH E ""P
33 S 333 3
33 S 333 3
33 S 3
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)
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