Plc Program; Tasks Of The Plc Program - Siemens SINUMERIK 880 SW 6 Planning Manual

01.93
1.2

PLC program

The following Subsection outlines the following:
• The structure of the PLC program
• The tasks of the PLC program
• The distribution of tasks between the PLC operating system and PLC user program and
• The basic mechanisms of signal and data transfer.
The "PLC 135 WB Planning Guide" for the SINUMERIK 880
contains a detailed introduction to programming the PLC.
1.2.1

Tasks of the PLC program

The SINUMERIK 880 can be used for a variety of tasks. The "classic" task of the NC,
executed here by the NC area (NC CPU and SERVO CPU), is to control the drives. The NC
obtains the necessary enables from the NC/PLC interface.
The machine signals required to control the drives are supplemented by various other signals
which differ from machine to machine and cannot be processed by the customary NC function-
ality. The control is matched to the signal scope of the machine by accordingly equipping the
PLC area with I/O submodules to register and switch the machine-specific signals.
The PLC user program must provide the link between the machine-specific signals and the NC
functions. This requires the PLC user program to create the signals needed by the NC from
the machine-specific signals and, conversely, to generate the signals needed by the machine
from the control signals.
The PLC user program is also responsible for utilizing machines' special facilities that are not
covered by the usual NC functions. It must therefore implement these potential machine
functions and actuate and monitor them as necessary.
Facilities and
requirements of the
NC area
PLC program as a mediator between the machine and NC
© Siemens AG 1991 All Rights Reserved
SINUMERIK 880 (PJ)
PLC user
program
Machine manufacturer's knowledge
of the control and machine
6ZB5 410-0HE02
1 General Overview
1.2 PLC program
Facilities and
requirements of the
machine
1–11