Converting Byte to ASCII Character

Hello,
I am reading several BYTES from a PLC which each represent one ASCII character. How do I convert this so that WinCC will display the actual ASCII character and not the numeric ASCII code.

Any help would be greatly appreciated.

Cheers Mates!

R.K.

Hello, Rusty_K;
In WinCC tag management, you can set the type of data used by each tag used. Even if the value you collect from the PLC is purely numerical, you can determine how WinCC will treat the data.
Select the tag you want to display as a character (Open your channel configuration in Tag Management, double-click on the tag), open the droplist for data types, select "8-bit char" (my winCC is in French, so this might not bve the exact wording in english; Ipresume you will fing waht you need). Then go to runtime.
Hope this helps,
Daniel Chartier

Hey Dchartier,

What you mentioned is the very first thing I tried before I posted my question. However it still does not read it correctly and I'm not sure what I am doing wrong.

I have tried 2 methods :

1) I defined tag datatype as a 8 bit character (of length 1) while keeping the OPC address datatype as 8 bit unsigned value. This gave me an output of zero ( The 8 bit character I am reading is 57 > (9 in ASCII Format)

2) I defined both the tag datatype and OPC address datatype as 8 bit character (of length 1) and "string" respectively and this still did not work.

What am I missing?

Thanks for the help!

Cheers

R.K.

To view string characters in WinCC, the length of the tag has to be set to at least 3 and the tag type set to (Text tag 8-bit character set).

If you create a DB to store your strings and lets say you want 10 characters in the string. The string length in the DB must be set to 12. S7 uses the first 2 bytes to store string length data. When accessing the string from WinCC the tag will also have the length of 12.

S7-Example: address: DB1200.DBB0 Type: String [12]
WinCC- Example: address: DB1200.DBB0 Type: Text tag 8-bit character set Length: 12
In the above example, WinCC will display the characters starting with byte address DB1200.DBB2, which is the beginning of your 10 character string.

Just remember that the first 2 bytes are only used by the software.

Hope this helps,
Jeff M.