CODEWITHSUNDEEP
hexasciicodesys
Soul1986
Soul1986

Reputation: 3

Convert Hex bytes to an ASCII string (Codesys)?

I have 4 bytes:

Byte_0=0x31
Byte_1=0x32
Byte_2=0x33
Byte_3=0x34

And I would like to get a word_1=0x1234, where 1 is the conversion from hex to ASCII. Any ideas about how to get this?

Upvotes: 0

Views: 2982

Answers (2)

Sergey Romanov
Sergey Romanov

Reputation: 3080

In addition to previous suggestion there is another way to convert string to integer and bytes to string.

PROGRAM PLC_PRG
    VAR
        arBt : ARRAY[1..4] OF BYTE := [16#31, 16#32, 16#33, 16#34];
        pstrString : POINTER TO STRING(4);
        iInt : INT;
    END_VAR

    pstrString := ADR(arBt); // now pstrString^ is equal to "1234"
    iInt := STRING_TO_INT(pstrString^); // now iInt = 1234 number
END_PROGRAM

If you have Codesys 2.3 then delete [ brackets in [16#31, 16#32, 16#33, 16#34].

Upvotes: 2

kolyur
kolyur

Reputation: 514

There may be an internal function available to translate an ASCII text digit to its numerical value, but you can easily write one yourself:

FUNCTION Ascii_To_Byte : WORD

VAR_INPUT ascii : BYTE

IF ascii>=16#30 AND ascii<=16#39 THEN  // range 0-9
  Ascii_To_Byte := ascii - 16#30;
ELSIF ascii>=16#41 AND ascii<=16#46 THEN  // range A-F
  Ascii_To_Byte := ascii - 16#41 + 16#0A;
ELSE
  Ascii_To_Byte := -1  // error condition, invalid input

Then it's just a matter of converting the values and bit shifting:

word_1 := SHL(Ascii_To_Byte(Byte_0), 12) + SHL(Ascii_To_Byte(Byte_1), 8) + SHL(Ascii_To_Byte(Byte_2), 4) + Ascii_To_Byte(Byte_3)

(Code written in TwinCAT, may be slightly different in Codesys.)

Upvotes: 0

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