13.8
Structure and functions of the basic program
General
The program is modular in design, i.e. it is structured according to NCK functions.
In the operating system, a distinction is made between the following levels of execution:
•
Start-up and synchronization (OB 100)
•
Cyclic mode (OB 1)
•
Process interrupt handling (OB 40)
•
Diagnostic interrupt, module failure processing (OB 82, OB 86)
Each section of the basic program - as illustrated in the figure below - must be called by the user in OBs 1, 40
and 100.
Basic Functions
Function Manual, 09/2011, 6FC5397-0BP40-2BA0
P3: Basic PLC Program for SINUMERIK 840D sl
13.8 Structure and functions of the basic program
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