250
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
Related devices
1. Relationship between the flag operation and the sign (positive or negative) of a numeric
value
→
For the flag operations, refer to Subsection 6.5.2.
Cautions
1. When using a 32-bit operation instruction (DSUB or DSUBP)
When specifying word devices, a 16-bit word device on the low-order side is specified first, and then a word
device with the subsequent serial number is automatically set for the high-order 16 bits.
For preventing number overlap, it is recommended to always specify an even number, for example.
2. When specifying a same device as the source and destination
A same device number can be specified for both the source and the destination.
In this case, note that the addition result changes in every operation cycle if a continuous operation type
instruction (SUB or DSUB) is used.
Device
Name
Description
M8020
Zero
ON : When the operation result is 0
OFF: When the operation result is other than 0
M8021
Borrow
ON : When the operation result is less than
−
32768 (in 16-bit operation) or
−
2,147,483,648 (in 32-bit operation)
OFF: When the operation result is not less than
−
32768 (in 16-bit operation) or
−
2,147,483,648 (in 32-bit operation)
M8022
Carry
ON : When the operation result is more than 32767 (in 16-bit operation) or
2,147,483,647 (in 32-bit operation)
OFF: When the operation result is not more than 32767 (in 16-bit operation) or
2,147,483,647 (in 32-bit operation)
Zero flag
−
2,
−
1, 0,
−
32768
Borrow flag
Zero flag
−
2,
−
1, 0,
−
2,147,483,648
Borrow flag
The most
significant bit of
data becomes
"1".
Zero flag
32767, 0, 1, 2
Carry flag
Zero flag
2,147,483,647, 0, 1, 2
Carry flag
Zero flag
−
1, 0, 1
Zero flag
−
1, 0, 1
The most
significant bit
of data
becomes "0".
FNC 21
SUB
D 0
K 25
D 0
X001
(D 0)
−
25
→
(D 0)