POUs are used for structuring the complete user logic. Individual Units may invoke other ones, however a recursive POU structure is not allowed.
POUs are either defined as standard by default or user specific depending on the specific automation problem to be solved by the User Logic.
Control FPWIN Pro7 differentiates between the POU Header, which contains the declared variables, and the Body, which contains the POU’s algorithm.
Due to different requirements for the solution of a sub-problem, different types of POUs are provided.
The different POU types are Functions, Function Blocks and Programs.