Starting Up The Plc - Siemens Sinumerik 802D sl Instruction Manual

Starting Up the PLC

General
The PLC is intended to control machine-related functional sequences. It is realized as a soft-
ware PLC.
The user program – a PLC cycle – is always executed in the same order of sequence.
S Refresh of the process image (inputs, user interface, timers)
S Processing of communication requests (operator panel, PLC 802 programming tool, ver-
S Editing of the user program
S Evaluation of alarms
S Output of the process image (outputs, user interface)
During the cycle, the PLC executes the user program from the first to the last operation.
The user program accesses the hardware inputs/outputs only via the process image and not
directly. The PLC refreshes the hardware I/Os at the beginning or end of program execution.
Thus, these signals are stable over a whole PLC cycle.
The user program can only be created using the PLC 802 Programming Tool, version 3.1
and higher, with the S7-200 programming language using ladder diagram. Ladder diagram is
a graphical programming language for representing electric circuit diagrams.
Important
PLC 802 Library with a description, which can be installed from the toolbox CD is offered
as the basis for the PLC user program. This provides a subroutine library and a sample pro-
gram for a milling machine.
Note
If the stop and reset buttons on the machine control panel are not realized as normally clo-
sed contacts, an open circuit cannot be detected.
Monitoring can be performed using software solutions, as shown in the example MCP_802D
(SBR 34) from the subroutine library.
Siemens Automation Parts
SINUMERIK 802D sl Instruction Manual (BA), 05/2005 Edition
6FC5 397-0CP10-1BA0
sion 3.0 and higher)
11
11-163