I want to send strings to the rs232 which needs to be 1 byte at a time.

The CoDeSys RS232 tutorial is missing the function code which would show me this so any assistance would be great.

Essentially I imagine something like:

s string;

b byte;

for i := 1 to len(s) do

b := string_to_byte(mid(s,1,i));

SendChar(b);

end_for;

I get error with the conversion from string to byte in this example.

Or perhaps a string converted to array of bytes and then iterate through the index to send each byte.

you can find examples for this code in the open source library OSCAT.LIB

to be downloaded from w www.oscat.de w

pls look at the modules buffer_to_string and string_to_buffer

Thanks Hugo. Is good.

For anyone else interested, below is what I did minus full error handling.

My function is arbitrarily set to handle up to 80 characters.

Calling function:

FUNCTION F_SEND_TEXT_RS232 : BOOL

VAR_INPUT

sText : STRING(80);

END_VAR

VAR

i : INT;

SendData: FB_PUT_RS232_CHAR;

fbGetRS232TxBufCount : FB_GET_RS232_TX_BUF_COUNT;

abText : ARRAY[0..80] OF BYTE;

iLength : INT;

END_VAR

F_STRING_TO_BYTE_ARRAY(sText,0,ADR(abText),SIZEOF(abText));

FOR i := 0 TO LEN(sText) DO

  REPEAT

    fbGetRS232TxBufCount();

  UNTIL

    fbGetRS232TxBufCount.Status = C_NO_ERR

  END_REPEAT;

    SendData(bByte := abText[i]);

END_FOR;

F_SEND_TEXT_RS232 := TRUE;

Implementation of string to byte array:

FUNCTION F_STRING_TO_BYTE_ARRAY : BOOL

( Usage: F_STRING_TO_BYTE_ARRAY(str, pos, adr("array"),sizeof("array")); )

VAR_INPUT

str : STRING(80);

pos : INT;

pt : POINTER TO ARRAY[0..79] OF BYTE;

size : UINT;

END_VAR

VAR

ps : POINTER TO BYTE;

i: INT;

end: INT;

END_VAR

ps := ADR(str);

end := MIN(pos + LEN(str) - 1,UINT_TO_INT(size));

FOR i := pos TO end DO

pt^[i] := ps^;

ps := ps + 1;

END_FOR;

F_STRING_TO_BYTE_ARRAY := TRUE;

Another one simple method is to declare the 'string' and the 'byte array' on the same direct address in 'M' memory.

Igor, could you give an example for this. Would be greatly appreciated.

Norm.

there is a simple solution to you're problem

declare a pointer byte array with the same size as you're string

byByte:BYTE;

sString:STRING(8 ); (a normal string has a size of 80 chars)

abyByte: pointer to POINTER TO ARRAY[0..7] OF BYTE;

abyByte:=ADR(sString); (if lengths do not match you can get real weird problems)

byByte:=abyByte^[i];

norm.boessler hat geschrieben:
Igor, could you give an example for this. Would be greatly appreciated.
Norm.

I have made a little sample showing how the addressing overlap works. It includes a visualization for demonstration. Once you unzip it, you should be able to import it into a new project and run it in simulation mode.

When you define variables that overlap in the marker address area, in this example a string and an array of bytes, it is like a union in C. You can put a string into the string variable and then each character can be pulled out from the overlapping byte array.

In the program, I only access MyString but as soon as you copy a string into the MyString variable, the bytes of it are immediately available in the MyBArray array.

Here is the Text if you can't import the attached file.

VAR_GLOBAL
(*  Declare the string and byte array at the same location in marker memory  *)
(* In practice, this may be in a global variable file for access by other rouines *)
   MyString   AT %MW0:      STRING(80);
   MyBArray   AT %MW0:      ARRAY [0..79] OF BYTE;
END_VAR
PROGRAM PLC_PRG
VAR
   Init:            BOOL := TRUE;
   MyBool:      BOOL;
   MyBoolOS:      R_TRIG;
   MyInt:         INT:=0;
   MyList:       ARRAY [0..4] OF  STRING(80) :=
      'One String', 'Two String', 'Three String', 'Four String', 'Five String';
END_VAR
IF Init THEN
   MyString   := MyList[MyInt];
   MyInt      := MyInt + 1;
   Init         := FALSE;
END_IF
MyBoolOS(CLK:=MyBool );
IF MyBoolOS.Q THEN
   MyString   := MyList[MyInt];
   MyInt      := MyInt + 1;
   IF MyInt >4 THEN MyInt := 0; END_IF
END_IF

OVERLAP.zip [1.22 KiB]

Great examples. I've learned much from this. Thanks to all who helped!

Originally created by: HASAN SERKAN DURMU&#3

Norm,

Can you please share lib that you used for coding your rs232 sample program since my sample program giveS an error which has mentioned about unknown type FB_PUT_RS232_CHAR and unknown type FB_GET_RS232_TX_BUF_COUNT.

i am looking forward your response,

Best Wishes,

You can also use a pointer for this, similar to the M solution above but without the need to know the M address of the source string.

PROGRAM PLC_PRG
VAR
   Text : STRING;
   Index: INT;
   Char : POINTER TO BYTE;
END_VAR
Text:= 'Hello world!';
Char:= ADR(Text);
FOR Index:=0 TO LEN(Text) DO
   Send(Char^);
   (* Goto the next character *)
   Char:= Char + 1;
END_FOR;