Technical data

System Software for S7-300/400 System and Standard Functions - Volume 1/2
A5E00709327-01
17-1
17 PROFInet
17.1 Background Information on SFCs 112, 113 and 114
Note
By default, the operating system updates the PROFInet interface as well as the DP
interconnections at the scan cycle check point. However, if you have disabled the
automatic updates in your configuration (e.g. to have better influence on the timing
in the CPU), you have to perform the updates yourself. To do this, call SFCs 112 to
114 at suitable times.
The updates mentioned here can only be disabled as a group in the configuration.
Shadow Memory
The interface DB is the user program interface for the PROFInet components. To
ensure that the inputs and output are consistent when the associated program
sections are running, each interface DB has an identically structured memory area
that is managed by the operating system. This area is called "shadow memory." In
your program, you can only access the interface DB, and other (external)
PROFInet components can only access the shadow memory. This arrangement
prevents conflicts in accessing the inputs and outputs of the interface DB.