20 ARITHMETIC OPERATION FUNCTIONS
20.3 Subtraction
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20
20.3
Subtraction
SUB(_E)
These functions output the difference of input values ((s1) - (s2)).
Setting data
■
Descriptions, types, and data types
Processing details
■
Operation processing
• These functions subtract the INT, DINT, or REAL type data input to (s1) and (s2) ((s1)-(s2)), and output the operation result
from (d) in the same data type as (s).
Ex.
Data type is INT
• A value input to (s1) and (s2) is the INT, DINT, or REAL type data value.
• If an underflow and an overflow occur in the operation result, the result will be output as follows from (d).
• When the operation result is 0, the zero flag (SM8020) turns on.
Ladder diagram, FBD/LD
Structured text
[Without EN/ENO]
[With EN/ENO]
[Without EN/ENO]
d:=SUB(s1,s2);
[With EN/ENO]
d:=SUB_E(EN,ENO,s1,s2);
Argument
Description
Type
Data type
EN
Execution condition (TRUE: Execution, FALSE: Stop)
Input variable
BOOL
s1(IN1), s2(IN2)
Input
Input variable
ANY_NUM
ENO
Output status (TRUE: Normal, FALSE: Abnormal)
Output variable
BOOL
d(SUB(_E))
Output
Output variable
ANY_NUM
Data type is INT
Data type is DINT
Data type is REAL
• Even if underflow or overflow occurs in the
operation result, it is not regarded as an
operation error. "SUB_E" outputs "TRUE" from
ENO.
[Example 1]
32767-(-2)=1
(7FFFH)-(0002H)=(0001H)
The most significant bit becomes 1, and the carry
flags (SM716 and SM8022) turn on.
[Example 2]
-32768-2=-1
(8000H)-(0002H)=(FFFFH)
The most significant bit becomes 0, and the borrow
flag (SM8021) turns on.
• Even if underflow or overflow occurs in the
operation result, it is not regarded as an
operation error. "SUB_E" outputs "TRUE" from
ENO.
[Example 1]
2147483647-(-2)=-2147483647
(7FFFFFFFH)-(FFFEH)=(80000001H)
The most significant bit becomes 1, and a negative
value is output.
[Example 2]
-2147483648-2=2147483646
(80000000H)-(0002H)=(7FFFFFFEH)
The most significant bit becomes 0, and a positive
value is output.
An operation error occurs and an undefined value
is output.
s1
d
s2
EN
ENO
d
s1
s2
INT
12345
-
INT
6789
INT
5556
(s1)
(s2)
(d)
Summary of Contents for MELSEC iQ-F FX5
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