Technical data

Overview of the Chapters
Chapter 1 This informs you about the areas of application of the S5-135U
programmable controller with the CPU 928B and its device structure.
It explains the typical mode of operation of the CPU and illustrates
how a CPU program is structured.
The chapter also contains suggestions about how to tackle
programming and which characteristics of the CPU 928B are
important for programming.
If you have already worked with the CPU 928B-3UB11 and want to
know the differences between these CPU and the CPU 928B-3UB12
you will find this information in this chapter.
Chapter 2 This explains the components of a STEP 5 user program and how the
program can be structured.
Chapter 3 This is intended for readers who do not yet have much experience of
using the STEP 5 programming language. It therefore deals with the
basics of STEP 5 programming and explains the STEP 5 operations in
detail (with examples).
Experienced readers who may find that the information about specific
operations in the pocket guide is inadequate, can use Section 3.5 as a
reference section.
Chapter 4 This provides an overview of the modes and program execution levels
of the CPU 928B. It provides you with detailed information about
various start-up modes and the associated organization blocks in
which you can program your routines for differrent start-up situations.
The chapter also explains the differences between the program
execution levels "cyclic processing", "time-controlled processing" and
"interrupt-driven processing" and which blocks are available for your
user program.
Chapter 5 This informs you about errors to be avoided when planning and
writing your STEP 5 programs.
The chapter tells you about the help you can obtain from the system
program for diagnosing errors and which reactions can be expected
and informs you about the blocks in which you can program reactions
to certain errors.
The chapter also explains the CPU 948 self-test.
How to Use this Manual
CPU 928B Programming Guide
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