Specifications

Basic Concepts for Programming an S7-200 CPU
4-2
S7-200 Programmable Controller System Manual
C79000-G7076-C233-01
4.1 Guidelines for Designing a Micro PLC System
There are many methods for designing a Micro PLC system. This section provides
some general guidelines that can apply to many design projects. Of course, you
must follow the directives of your own company’s procedures and of the accepted
practices of your own training and location. Figure 4-1 shows some of the basic
steps in the design process.
Partition your process or machine.
Create the functional specifications of the units.
Specify the operator stations.
Create the PLC configuration drawings.
Create a list of symbolic signal-naming conventions (optional).
Design the hard-wired safety circuits.
Figure 4-1 Basic Steps for Planning a PLC System
Partitioning Your Process or Machine
Divide your process or machine into sections that have a level of independence
from each other. These partitions determine the boundaries between controllers
and influence the functional description specifications and the assignment of
resources.