Creating A Plc Program - Siemens SINUMERIK 840D sl Commissioning Manual

5.4

Creating a PLC program

Introduction
The PLC program is constructed modularly. It comprises the following parts:
● PLC basic program
The PLC basic program organizes the exchange of signals and data between the PLC
program and the NC, HMI, and machine control panel components. The PLC basic program
is part of the SINUMERIK 840D sl Toolbox.
● PLC program (extension by the machine manufacturer)
The PLC program is the machine-specific part of the machine manufacturer by which the
PLC basic program is extended.
For example, the FB1 (boot block of the PLC basic program) must be supplied with
variables.
Additional information is provided in the "PLC
view/109767449)" Function Manual.
Cyclic operation (OB1)
From a chronological viewpoint, the basic program runs before the PLC program. The NC/PLC
interface is completely processed in cyclic operation. Cyclic monitoring is activated between
PLC and NC once booting and the first OB1 cycle have been completed. A PLC failure
produces alarm "2000 Sign-of-life monitoring PLC".
PLC program
The entry points for machine-specific components of the PLC program are located in the
following PLC basic program blocks:
● OB100 (restart)
● OB1 (cyclic processing)
● OB40 (process alarm)
CNC Commissioning: NC, PLC, Drive
Commissioning Manual, 12/2019, A5E48312804B AA
5.4 Creating a PLC program
(https://support.industry.siemens.com/cs/ww/en/
PLC commissioning
85