BYTE_TO_LREALEX

The conversion of unsigned numbers into floating-point numbers of the type LREAL is not supported in TwinCAT 2 on the Arm® platform. Unsigned numbers with the most significant bit set may possibly be implicitly converted into negative floating-point numbers. The function described here allows the explicit conversion of the type BYTE into a positive floating-point number of the type LREAL in TwinCAT 2 (even if the most significant bit was set and without compiler warning). You only need this function to be able to compile converted TwinCAT 2 projects without changes in TwinCAT 3.

Unsigned numbers of the type BYTE are always (implicitly and explicitly) converted into positive floating-point numbers in TwinCAT 3. For this reason this function can be dispensed with.

Return value

Name	Type	Description
BYTE_TO_LREALEX	LREAL

Inputs

VAR_INPUT
    in : BYTE;
END_VAR

Name	Type	Description
in	BYTE

Sample:

PROGRAM MAIN
VAR
    nByte  : BYTE := 16#FF;
    fLreal : LREAL := 0.0;
END_VAR

fLreal value	Tc2.x ARM	Tc2.x X86	Tc3.x ARM, X86, X64
`fLreal := nByte`	`+255, Warning 1105*`	`+255`	`+255`
`fLreal := BYTE_TO_LREAL( nByte )`	`+255, Warning 1105*`	`+255`	`+255`
`fLreal := BYTE#16#FF`	`+255, Warning 1105*`	`+255`	`+255`
`fLreal := 16#FF`	`+255`	`+255`	`+255`
`fLreal := BYTE_TO_LREALEX( nByte )`	`+255`	`+255`	`+255`
`fLreal := BYTE_TO_LREALEX( BYTE#16#FF )`	`+255`	`+255`	`+255`
`fLreal := BYTE_TO_LREALEX( 16#FF )`	`+255`	`+255`	`+255`

*Conversion of unsigned integer to LREAL is not supported. The value is used as signed instead.

Requirements

Development environment	Target platform	PLC libraries to be integrated (category group)
TwinCAT v3.1.0	PC or CX (x86, x64, Arm^®)	Tc2_Utilities (System)