Ok (Check Validity) And Not_Ok (Check Invalidity) Instructions - Siemens S7-1200 System Manual

Basic instructions
7.5 Math functions
7.4.3

OK (Check validity) and NOT_OK (Check invalidity) instructions

Table 7- 33 OK (check validity) and Not OK (check invalidity) instructions
LAD FBD
For LAD and FBD: When the LAD contact is TRUE, the contact is activated and passes power flow. When the FBD box
1
is TRUE, then the box output is TRUE.
Table 7- 34 Data types for the parameter
Parameter Data type
IN Real, LReal
Table 7- 35 Operation
Instruction The Real number test is TRUE if:
OK The input value is a valid real number
NOT_OK The input value is not a valid real number
A Real or LReal value is invalid if it is +/- INF (infinity), NaN (Not a Number), or if it is a denormalized value. A
1
denormalized value is a number very close to zero. The CPU substitutes a zero for a denormalized value in calculations.
228
SCL
Not available
Not available
1
1
Description
Tests whether an input data reference is a valid real
number according to IEEE specification 754.
Description
Input data
System Manual, 03/2014, A5E02486680-AG
S7-1200 Programmable controller