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13-3

Ladder Logic (LAD) for S7-300 and S7-400

C79000-G7076-C504-02

13.2 Compare Double Integer

The Compare Double Integer instruction carries out a compare operation on

the basis of 32-bit floating-point numbers. You can use this instruction like a

normal contact. This instruction compares inputs IN1 and IN2 according to

the type of comparison you select from the browser. Table 13-3 lists the valid

comparisons.

If the comparison is true, the result of logic operation (RLO) of the function

is 1. Otherwise it is 0. There is no negation of the compare output, because

this logic can also be handled by the inverse compare function.

Table 13-3 Types of Comparisons for Double Integers

Type of Comparison Symbols in Name at Top of Box

IN1 is equal to IN2. ==

IN1 is not equal to IN2. <>

IN1 is greater than IN2. >

IN1 is less than IN2. <

IN1 is greater than or equal to IN2. >=

IN1 is less than or equal to IN2. <=

Table 13-4 Compare Double Integer Box and Parameters (Example: not equal)

LAD Box Parameter Data Type Memory Area Description

CMP

<> D

IN1 DINT I, Q, M, D, L First value to compare

IN1

IN2

DINT

IQMDL

Second value to compare

IN2

DINT

econ

o compare

Description

Comparison Instructions

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