Since your RS232 data packet is so exact, you can create string tags that are exactly the right length.

Global:
  rs232_rcvd : STRING[18];
  rs232_data : STRING[6];

#startAt := 7; // start @ 8th position in source string, zero counts
#numCharsToCopy := 6; // 
rs232_data := MID(IN:=rs232_rcvd, L:=#numCharsToCopy, P:=#startAt); 

However, I recommend allowing the rs232_rcvd buffer be at least 2x the nominal max expected string size.  In this way, you can monitor the received data length for 2+ packets sent so quickly that the PLC sees them as a single string.

Use the F1-help and the Instruction Pane to find instructions - and how to use them. 

Fresh Engineer

Hi,

I'm currently working on RS232 Communication. Does anyone know how to convert byte to real that contains carriage return and line feed? This is the buffer that I receive.
Below is the example result I get:
Byte 0 to 6  is 16#20 which is Space.
Byte 7 to 12 is my results with a decimal point
Bytes 13 to 17 are my carriage return and line feed $R$L

I only need my results and converted them to REAL.

Instead of LEN, any other way to use the search function to trim the SPACE, Carriage Return and Line Feed?  Then, convert the result to REAL.

@Fresh Engineer:

Bonus note: The above code was built on the STRG_VAL sample given in..
[ LINK: Library with program examples for TIA Portal instructions ]

Your original post was quite specific which is why my suggestion was so specific.

Changing the rules changes the suggestions.

I suggest looking hard at the post by @qwazee above which considers the new information in the below quoted reply.

Fresh Engineer

Hi,

I tried MID, FIND, REPLACE and LEN. All of these need to insert a fixed number that the string to be trimmed. Anyway to let it search through the string? The array may start with byte 5 or 6 if the results number is larger.