Data Type: REAL, LREAL

The data types ‎REAL‎ and ‎LREAL‎ are floating-point types according to IEEE 754. Floating-point types are necessary when using decimal numbers and floating-point numbers in decimal notation or exponential notation.

Table 545: Target System
Data Type	Smallest value number	Largest value number	Memory
`‎REAL‎`	1.0E-44	3.402823E+38	32-bit
`‎LREAL‎`	4.94065645841247E-324	1.7976931348623157E+308	64 bits

Example

PROGRAM PLC_PRG
VAR
    rMax: REAL := 3.402823E+38; // Largest number
    rPosMin : REAL := 1.0E-44; // Smallest positve number
    rNegMax: REAL := -1.0E-44; // Largest negative number
    rMin: REAL := -3.402823E+38; // Smallest number

    lrMax: LREAL := 1.7976931348623157E+308; // Largest number
    lrPosMin : LREAL := 4.94065645841247E-324; // Smallest positve number
    lNegMax: LREAL := -4.94065645841247E-324; // Largest negative number
    lrMin: LREAL := -1.7976931348623157E+308; // Smallest number
END_VAR

NOTICE

Support for the ‎LREAL‎ data type depends on the target device in use. See the respective documentation as to whether or not the 64-bit type ‎LREAL‎ is converted to ‎REAL‎ or remains as ‎LREAL‎ when compiling the application. Conversion may result in the loss of information.

NOTICE

If the value of the ‎REAL‎/‎LREAL‎ number is outside of the value range of the integer, then an undefined result is yielded from a data type conversion from ‎REAL‎ or ‎LREAL‎ to ‎SINT‎, ‎USINT‎, ‎INT‎, ‎UINT‎, ‎DINT‎, ‎UDINT‎, ‎LINT‎, or ‎ULINT‎. The result depends on the target system. An exception error is also possible. To get code that is independent of the target system, the application has to catch out-of-range violations.

If the ‎REAL‎/‎LREAL‎ number is within the value range of the integer data type, then the conversion operates the same way on all systems.