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286
FX
3G
/FX
3U
/FX
3UC
Series Programmable Controllers
Programming Manual - Basic & Applied Instruction Edition
10 Arithmetic and Logical Operation (
+
,
−
,
×
,
÷
) – FNC 20 to FNC 29
10.2 FNC 21 – SUB / Subtraction
10.2
FNC 21 – SUB / Subtraction
Outline
This instruction executes subtraction using two values to obtain the result (A
−
B = C).
→
For the floating point subtraction instruction ESUB (FNC121), refer to Section 18.9.
1. Instruction format
2. Set data
3. Applicable devices
S
: This function is supported only in FX
3U
/FX
3UC
PLCs.
Explanation of function and operation
1. 16-bit operation (SUB and SUBP)
The contents of
are subtracted from
in the binary format, and the subtraction result is transferred
to .
• The most significant bit of each data indicates the sign (positive: 0 or negative: 1), and data are subtracted
algebraically.
5
−
(
−
8) = 13
• When a constant (K) is specified in
or
, it is automatically converted into the binary format.
2. 32-bit operation (DSUB and DSUBP)
The contents of [
+1,
] are subtracted from [
+1,
] in the binary format, and the
subtraction result is transferred to [
+1,
].
• The most significant bit of each data indicates the sign (positive: 0 or negative: 1), and data are subtracted
algebraically.
5500
−
(
−
8540) = 14040
• When a constant (K) is specified in [
+1,
] or [
+1,
], it is automatically converted into
the binary format.
Operand type
Description
Data type
Data for subtraction or word device number storing data
16- or 32-bit binary
Data for subtraction or word device number storing data
16- or 32-bit binary
Word device number storing the subtraction result
16- or 32-bit binary
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
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
3
3
3
3
3 3 3 3
S
3 3
3
3 3
3
3
3
3
3 3 3 3
S
3 3
3
3 3
3
3
3
3 3 3 3
S
3 3
3
DSUB
DSUBP
Mnemonic
Operation Condition
P
FNC 21
SUB
D
16-bit Instruction
7 steps SUB
SUBP
Mnemonic
Operation Condition
Continuous
Operation
Pulse (Single)
Operation
32-bit Instruction
13 steps
Continuous
Operation
Pulse (Single)
Operation
S
1
S
2
D
S
1
S
2
D
S
2
S
1
D
FNC 21
SUB
S
1
S
2
−
→
Command
input
D
S
1
S
2
D
S
1
S
2
S
2
S
2
S
1
S
1
D
1
D
1
FNC 21
DSUB
S
1
S
2
[ +1, ]
−
[ +1, ]
→
[ +1, ]
Command
input
D
S
1
S
2
D
S
1
S
2
D
S
1
S
1
S
2
S
2