Siemens Simatic S7 Series

Program instructions
7.4 Compare
S7-200 SMART
192 System Manual, 09/2015, A5E03822230-AC
7.4
Compare
7.4.1
Compare number values
The compare instructions can compare two number values with the same data type. You can
compare bytes, integers, double integers, and real numbers.
For
LAD and FBD
: When the comparison is TRUE, the compare instruction sets ON a
contact (LAD network power flow), or output (FBD logic flow).
For
STL
: When the comparison is TRUE, the compare instructions can load, AND, or OR a 1
with the value on the top of the logic stack.
Types of comparison
Six comparison types are available:
Comparison type
The output is TRUE only if
== (LAD/FBD)
= (STL)
IN1 is equal to IN2
<> IN1 is not equal to IN2
>=
IN1 is greater than or equal to IN2
<=
IN1 is less than or equal to IN2
>
IN1 is greater than IN2
<
IN1 is less than IN2
Selecting the data types to be compared
The data type identifier that you choose determines the required data type for the IN1 and
IN2 parameters.
Data type identifier
Required IN1, IN2 data type
B
Unsigned byte
W
Signed word integer
D
Signed double word integer
R
Signed real