Starting Up The Plc; Commissioning Of The Plc - Siemens SINUMERIK 802C Manual

4.3

Starting up the PLC

General
The PLC is a store–programmable logic controller for simple machines. It has no hardware of
its own and is used as a software PLC in the SINUMERIK 802C control system.
The task of the PLC is to control machine–related functional sequences.
The PLC executes the user program cyclically. A PLC cycle is always executed in the same
sequence of order.
S
Update process image (inputs, outputs, user interface, timers)
S
Process communication requests (Operator Panel, PLC 802 Programming Tool)
S
Execute user program
S
Evaluate alarms
S
Output process image (outputs, user interface)
The PLC executes the user program cyclically, starting from the first up to the final operation.
Access from user program is only carried out via the process image and not directly to the
hardware inputs or outputs. The hardware inputs and outputs are updated by the PLC at the
beginning and at the end of program execution. The signals are thus stable over a PLC cycle.
The user program can be created by means of the PLC 802 Programming Tool using the pro-
gramming language S7–200 in conjunction with ladder diagrams (LAD). A ladder diagram is a
graphical programming language to represent electrical circuit diagrams.
This Documentation describes the program structure and the instruction set of the PLC in de-
tail.
4.3.1

Commissioning of the PLC

The SINUMERIK 802C comes to the user with a simulation program included.
The SAMPLE user program is stored in the permanent memory. This sample program and the
documentation are included in the SINUMERIK 802SC Toolbox component "PLC802SC Li-
brary".
The simulation program is intended for the first function test of the control system after assem-
bling the control.
Internal simulation program
The simulation program is integral part of the 802C system software. The simulation program
allows operation of the control system without digital input and output modules. The user pro-
gram processes all firmly defined keys and the default setting of the axis keyboard (default).
Axes and spindle are switched to simulation mode. No real axis movement is carried out. The
Axis/Spindle Disable user signal is set for each axis. For this reason, the movements of the
axes and of the spindle are simulated virtually. The user can use this program to test the inter-
relation of the components Operator Panel / Machine Control Panel / ENC.
SINUMERIK 802C
6FC5 597–3AA20–0BP2 (01.02)
Start-Up
4.3 Starting up the PLC
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