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Description of the Function Blocks in the
Example
The following section describes the driver blocks used in the
example which control the interaction between the controller
board and the PLC.
Initialization Function FC 20:
When switching on the power supply, the controller board is
started via the pluggable parameterization memory. This
process is independent of the PLC and must be synchronized
with the application program. Driver block FC 20, called
during the PLC startup (OB 100), is responsible for
synchronization.