#1 S7COMM_AREA_V

[Anonymous]

The #define S7COMM_AREA_V is commented as /* don't know what it is */.

The V-area adresses the local variables of the calling function. You cannot reference the V-Area in your program directly, but if you pass a local variable to a subroutine (you know, S7s pass arguments by reference), the L-Reference of the calling function gets converted to a V-reference in the called function. You can see these references e.g. in the AR[12] registers.

so the item_areanames can be changed to

{ S7COMM_AREA_V, "callers local data (V)" },

[Thomas Wiens]

Hi,
it's a leftover by copying the defines from the libnodave-library. I've never tested if it is possible to read or write local data or callers (vorgaenger) local data over ethernet. If it's not possible I will delete the defines.
The area IDs are the same as the IDs which are used for the area in S7 ANY-pointers.