Automating Manufacturing Systems - Process Control and ...

plc basic functions - 15.18
CMP
expression
int_3 = int_2
CMP
expression
int_3 int_2
CMP
expression
int_3 < int_2
CMP
expression
int_3 int_2
CMP
expression
int_3 >= int_2
O_0
O_1
O_2
O_3
O_4
O_5
Figure 15.17
Equivalent Statements Using CMP Statements
Expressions can also be used to do more complex comparisons, as shown in Figure
15.18. The expression will determine if B is between A and C.
CMP
expression
(B > A) & (B < C)
X
Figure 15.18
A More Complex Comparison Expression
The LIM and MEQ functions are shown in Figure 15.19. The first three functions
will compare a test value to high and low limits. If the high limit is above the low limit and
the test value is between or equal to one limit, then it will be true. If the low limit is above
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