Programming the PLC
4
4.1 General information about the PLC program
4.1.1
Introduction
The PLC program is constructed modularly. It comprises the two parts:
● PLC basic program
The PLC basic program organizes the exchange of signals and data between the PLC user
program and the NCK, HMI, and machine control panel components.
Use the appropriate PLC basic program depending on the firmware version of an NCU.
– SINUMERIK 840D sl PLC basic program V4.5.x.x
– SINUMERIK 840D sl PLC basic program V4.7.x.x
– SINUMERIK 840D sl PLC basic program V4.8.x.x
● PLC user program
The PLC user program is the user-specific part of the PLC program by which the PLC basic
program has been augmented or extended.
4.1.2 Execution structure
Overview
The following organization blocks contain the entry points for the appropriate parts of the PLC
basic program (and user program):
● OB100 [OB100] (Cold restart)
● OB1 [OB1] (Cyclic execution)
● OB40 [OB40] (Process interrupt)
● Asynchronous errors
– OB82 [OB82] (Diagnostics alarm)
– OB86 [OB86] (Module failure)
The RUN_UP [FB1] function block is the startup block of the PLC basic program. The call of
RUN_UP [FB1] in the OB100 [OB100] must be supplied with data.
The following figure illustrates the structure of the PLC program:
SINUMERIK STEP 7 Toolbox V15.1
Configuration Manual, 12/2018, A5E46279635B AA 55
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