hi.

if you  use the "ROR" function with 16 bit , rotate the word1 and word2.

example : this picture.

DATA_BLOCK DB1

STRUCT Register1: INT; // First 16-bit register (read from Modbus)

Register2: INT; // Second 16-bit register (read from Modbus)

CombinedDWord: DWORD; // Combined 32-bit DWORD

FloatValue: REAL; // Converted float value

END_STRUCT

END_DATA_BLOCK

FUNCTION_BLOCK FB1

VAR_INPUT MB_DATA: ARRAY[0..1] OF INT; // Data read from Modbus (2 registers)

END_VAR

VAR

Register1: INT;

Register2: INT;

CombinedDWord: DWORD;

FloatValue: REAL;

TempRegister2: DWORD; // Temporary variable

TempRegister1: DWORD; // Temporary variable

ShiftedRegister2: DWORD; // Temporary variable to hold the shifted value

END_VAR

// Get the data read from Modbus

Register1 := MB_DATA[0];

Register2 := MB_DATA[1];

// Safe conversion from INT to DWORD

TempRegister1 := WORD_TO_DWORD(INT_TO_WORD(Register1));

TempRegister2 := WORD_TO_DWORD(INT_TO_WORD(Register2));

// Use SHL function to shift 16 bits to the left

ShiftedRegister2 := SHL(IN := TempRegister2, N := 16);

// Combine in CDAB format

CombinedDWord := ShiftedRegister2 OR TempRegister1;

// Convert the combined DWORD to float

FloatValue := DWORD_TO_REAL(CombinedDWord);

// Write the results to the global data block

DB1.Register1 := Register1;

DB1.Register2 := Register2;

DB1.CombinedDWord := CombinedDWord;

DB1.FloatValue := FloatValue;

// Use FloatValue for further processing if needed