17 ARITHMETIC OPERATION FUNCTIONS
17.3 Subtraction
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17
17.3 Subtraction
SUB(_E)
These functions output the difference of input values ((s1) - (s2)).
■Descriptions, types, and data types
■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).
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 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, s2 Input Input variable ANY_NUM
ENO Output status (TRUE: Normal, FALSE: Abnormal) Output variable BOOL
d 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.
INT
12345 -
INT
6789
INT
5556
(s1) (s2)
(d)
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