Validation Functions

Help Contents

Introduction

Fernhill SCADA supports these validation functions defined by the IEC 61131-3 standard:

FunctionParameter TypeDescription
IS_VALID ANY_REAL Return TRUE if the parameter is a valid REAL number.
IS_VALID_BCD ANY_BIT Return TRUE if the parameter is valid BCD.

In addition Fernhill SCADA supports these functions as an extension to the IEC 61131-3 standard:

Function Parameter Type Description
IS_DEFINED ANY Returns TRUE if the parameter is defined.

Remarks

The Validation functions check if the input parameter contains a valid value.

The function IS_VALID() checks the input parameter represents a valid floating point number. The function returns FALSE, if the input parameter is not a number (NaN) or infinite.

The function IS_VALID_BCD() checks the input parameter is valid BCD.

The function IS_DEFINED() checks the input parameter is a valid value. This function is useful to check whether a tag reference is valid. For example, the expression IS_DEFINED( %"Tag Name" ) will return:

Standards Compliance

Table 39 - IEC 61131-3 Third Edition.

Further Information

Generic Data Types

To learn about generic data types such as ANY_INT, ANY_NUM, ANY_MAGNITUDE.

Time Functions

To learn about arithmetic operations on date and time types.

Common Elements

To learn about other language Common Elements.

Glossary

For the meaning of terms used in Fernhill SCADA.