S7-300 & AGP-3500T (ProFace) Operator Panel

[Alex3110]

S7-300 (CPU 315-2 DP) PLC works with AGP-3500T (ProFace) Operator Panel via TCP/IP.
I suppose the panel performs some function, which normally are performed by PLC. In the panel "GP-Pro Ex" project I see some D-scripts. I still don't understand what do those scripts do, since I only worked with WinCC Flexible before.
In particular, I suppose that panel calculates the value of current technological process stage in "INTEGER" - format and sends it to PLC cyclically .
I think so cause the PLCs bits that are responsible for the stages, are only read in PLC program. So they are not written ANYWHERE and thus they must come to PLC externally.
If it's so as I think, then where can I see that in my "GP-Pro Ex" - project ?
Where can I find a place which forms the above mentioned values for technological process stages.
Has anyone a VIDEO tutorial (or web-reference) on how to work with "GP-Pro Ex" ?

Thanks in advance.
Alex.