Technical data

Basics of Designing a Program Structure
4.2 Blocks in the User Program
Programming with STEP 7
Manual, 05/2010, A5E02789666-01 95
One Instance DB for Several Instances of Different FBs (Multiple Instances)
In a function block you can call the instances of other existing FBs. You can assign the instance
data required for this to the instance data block of the calling FB, meaning you do not need any
additional data blocks for the called FBs in this case.
For these multiple instances in one instance data block, you must declare static variables with the
data type of the called function block for each individual instance in the declaration section of the
calling function block. The call within the function block does not then require an instance data
block, only the symbolic name of the variable.
In the example in this figure, the assigned instance data are stored in a common instance DB.