Home > Automation > PLC (Programmable Logic Controller)
Download
158
times
Topic under PLC (Programmable Logic Controller)
Source: www.doctortee.net
File size: 262 KB, 42 pages
File type: pdf
Last download on:
Tue May 21, 2013 12:04:37 PM
Short Desciption:
This chapter brings together the digital elements introduced in Chapter 4 and Chapter 5
to show how a microprocessor based computer system can be created. The chapter
begins with a more detailed examination of the state machine concept introduced in
Chapter 4 and moves on to the microprocessor and its interaction with other elements
via memory mapping techniques. The elements are then brought to show how a
computer system is formed. This chapter also covers interrupt programming and
polling techniques, multi-tasking and paging.
Summary:
In order to maintain an accurate perspective on the capabilities of the computer, a
microprocessor, or Central Processing Unit (CPU), should be viewed as general-
purpose, software-programmable state machine. This device can be coupled to a few
basic elements, such as memory chips and other interfacing devices, to create simple
control systems. However, we can also combine a microprocessor with other devices
such as memory chips, disk drives, graphics controller cards, screens, keyboards, etc. to
form another standard package that can be used for both analysis and control. We call
that device a computer.
The term microprocessor can be somewhat misleading. Although it is intended to
convey the size of the silicon onto which it is embedded, many still equate the term
"micro" with low performance and this is certainly no longer the case. In general, we
refer to a microprocessor as being a single chip that is used as the CPU of a computer
or computer-based system. Many computers have CPUs that are composed of a
number of chips. Those chips, working together, have the same overall functionality of
a single microprocessor. Historically, larger computer systems used multiple-chip
CPUs and smaller computers used single-chip CPUs (microprocessors). However,
there is currently no simple way of telling whether a multiple-chip CPU is more or less
powerful than a single-chip CPU (microprocessor). There are many factors that
influence performance and the historical demarcation is no longer relevant. In this text,
therefore, when we talk of microprocessors, we are really talking about CPUs, since the
basic principles apply to both single and multiple chip systems.
In discussing microprocessors, one inevitably comes across a "sister" product
known as a Digital Signal Processor or DSP. There are some key differences between
the architecture of a microprocessor and that of a DSP. Microprocessors have
traditionally been developed on the so-called "Von Neumann" architecture, whereas
DSPs have been developed along the so-called "Harvard" architecture. The difference
is that microprocessor based program execution depends upon program instructions and
data being stored together, whereas DSP program execution depends upon isolation of
program instructions and data. We shall see the ramifications of this a little later when
we examine microprocessor program execution. However, in simple terms, the
Harvard architecture enables a DSP to carry out common control functions (digital
filtering, Fast Fourier Transforms, etc.) for a lower cost per given speed than the Von
Neumann architecture. This performance advantage is offset by the relatively low
volumes in which DSPs are produced. DSPs are therefore used for specialised control
functions, involving significant amounts of digital processing, whereas microprocessors
are used for both control and general computing.
Bookmark or share this info on Google+ and leave comment at below :
People who downloaded this also viewed in this sites:
Topics:
Objectives:
• Be able to understand and design basic input and output wiring.
• Be able to produce industrial wiring diagrams.
• PLC...
SLC 500 Systems Overview: The SLC 500 consists of a SLC 5/04 processor, five IO modules, a power supply, and a Panleview 600 in an integrated...
Describe the major features of the IEC 1131-3 standard for PLC programming; Describe the major syntax conventions of the SFC programming language;...
Leave comment :
"State Machines and Microprocessor Systems "
Related Free Files
Introduction to ControlNet with ControlLogix... - Download: 76 times The Design of a Portable Programmable Logic... - Download: 626 timesPLC Basics... - Download: 6261 timesPROGRAMMABLE CONTROLLERS THEORY AND I... - Download: 532 timesDesign of safety systems with Programmable... - Download: 205 timesThe PLC Hardware Environment... - Download: 698 timesProgrammable Logic Controllers... - Download: 571 timesPLC Design Exercise adn Problems... - Download: 199 timesSLC 500 Instruction Set Reference Manual ... - Download: 186 timesOMRON PLC-based Process Control Engineering... - Download: 577 times
