Problems reading a String With Mp277-10

This is the configuration:
- MP277 10 Touch, configured with WinCC flexible 2008 SP1 HF2
- CPU S7-315 2DP
- If I write in the DB of PLC "ABCDEFGH" I always get in the HMI "CDEFGH"
- If I write in the DB PLC "CDEFGH" I always get in the HMI "EFGH"
I always loose the two characters on the left.
The lenght of the String is setup for 256 Bytes (254 characters)
I tried with a TP177B 6" mono and works OK.

I dont know how you have configured the string, but in S7 strings the first two bytes are the reserved length and the actual used length.
Are you writing some characters (not a string) into the individual bytes via a VAT ?
If so, you should either not touch the first two bytes, or make sure that they contain values that the 1st two bytes represent the length of the string.
I.e. "hi there" =
254(dec)-8(dec)-"h"(char)-"i"(char)-space(char)-"t"(char)-"h"(char)-"e"(char)-"r"(char)-"e"(char)

Can you post some images of screen shots of the DB and of the text I/O field properties?

Thank you for the help. I think I found the problem, but not the solution.
The Problem is that I have an OPC running, and the string is coming from the PC. Since the OPC doesn't know how the PLC Strings works, is writing from Byte Zero on, when it should start writin to byte 2. Is there a way to correct this in the PLC?

Which OPC server are you using ?
I would guess that OPC STRINGs works the same as S7 STRINGs.
But I dont have so much experience with this though.

JesperMP said:

Which OPC server are you using ?
I would guess that OPC STRINGs works the same as S7 STRINGs.
But I dont have so much experience with this though.

Click to expand...

The OPC is from Vipa