Writing A Program; Methods Of Representation; Step 5 Operations - Siemens SIMATIC S5-90U System Manual

S5-90U/S5-95U
7 Introduction to STEP 5
This chapter explains how to program the S5-90U/S5-95U. It describes how to write a program, how
the program is structured, the types of blocks the program uses, and the number representation of
the STEP 5 programming language.
7.1

Writing a Program

A control program specifies a series of operations that tell the programmable controller how it has to
control a system. You must write the program in a very special language and according to specific
rules so that the programmable controller can understand it. The standard programming language
that has been developed for the SIMATIC S5 family is called STEP 5.
7.1.1

Methods of Representation

The following methods of representation are possible with the STEP 5 programming language.
• Statement List (STL)
STL represents the program as a sequence of operation mnemonics. A statement has the fol-
lowing format.
002:
Relative address of the statement in a particular block
The operation tells the programmable controller what to do with the operand. The parameter in-
dicates the operand address.
• Control System Flowchart (CSF)
CSF represents logic operations with graphics symbols.
• Ladder Diagram (LAD)
LAD graphically represents control functions with circuit diagram symbols.
• GRAPH 5/GRAPH Mini
GRAPH 5 describes the structure of sequence control systems. The restricted use of GRAPH 5
is possible only in the S5-95U.
You cannot use CSF, LAD, or GRAPH 5/GRAPH Mini with the PG 605 and PG 615 programmers.
EWA 4NEB 812 6115-02b
A I 32.0
Introduction to STEP 5
Operation
Operand
Parameter
Operand ID
7-1