Serial Port Complete

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More books in category: Computer Interfacing

by: Jan Axelson, Jan Axelson

Topics include: open baudmode, hex datain, device control block, access serial ports, logic high output, var byte, collision detecting, handshaking lines, cable delay, handshaking signals, transmit buffer, disable the driver, isolated interface, parallel termination, port bits, hardware handshaking, interface chips, biasing resistors, invert the signals, master node, software handshaking, transmitting node, logic low, slave node, only one driver

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Editorial Reviews Test and Measurement World, October 1998 The part of the book I liked most comes in the section that describes how to connect serial devices. Axelson covers not only RS-232 communications but also RS-485, a serial standard that allows for party-line or multi-drop connections. You would spend a lot of time looking for all the information that the book collects in one place. If you plan to use a serial port in any sort of application, buy this book. It should go on your bookshelf alongside Axelson's earlier book, Parallel Port Complete. Nuts and Volts, Sept '98 Serial Port Complete is an accurate title. This book covers everything you'd ever want to know about serial ports and network projects. And it's not all theory. This is a very practical book, full of detailed examples - including Stamps and Visual Basic. This book is a "must-have" for serious experimenters. Industrial and Control Systems, October 1998 Anyone who wants to build equipment and connect it to a computer will need the information covered here. It covers everything from the basic electrical and physical parameters, cables, and basic architecture to programming for PCs and microcomputers. Embedded Systems Programming, January 1999 Axelson's book is about as complete a reference as you'll find on serial communications. The code could save you some time; the reference material surely will.

EDN Review: Despite the book's detailed technical content, the style is clear. Although it contains enough material to satisfy most hardware and software engineers who develop products containing communication ports, the book should also prove useful to serious hobbyists. Nevertheless, despite its broad appeal, Serial Port Complete is far from watered-down pablum. Book Description serial interface information to jump-start projects on several platforms. This it the first book to have extensive on RS-485 , a widely used, industry standard interface for networks. This reference features original content based on the author's firsthand research and experience, not just rewritten specifications and marketing materials. Programmers, engineers and developers will use the designs in this book to get projects up an running quickly. Installation and maintenance staff will find tips for ensuring reliable operation and problem tracking. Students and computer enthusiast can use the book's complete, original examples and tools to design experimental projects for several computer platforms. Download Description This is the first book to have extensive detail on RS-485, a widely used, industry-standard interface for networks. This reference features original content based on the author's firsthand research and experience, not just rewritten specifications and marketing materials. Programmers, engineers, and developers will use the designs in this book to get projects up and running quickly. Installation and maintenance staff will find tips for ensuring reliable operation and problem tracking. Students and computer enthusiasts can use the book's complete, original examples and tools to design experimental projects for several computer platforms. --This text refers to the Digital edition.

Book Info Provides everything you need to design, program, install, troubleshoot RS-232, RS-485 links and networks. Softcover. 3 1/2 inch disk included. Excerpted from Serial Port Complete by Janet Louise Axelson, Jan Axelson. Copyright © 1998. Reprinted by permission. All rights reserved From Chapter 6, Linking Two Devices with RS-232: Port-powered Circuits Some low-power circuits that connect to an RS-232 port don't need an external power supply. Instead, they draw all the power they need from the interface itself. The power comes from unused outputs. To meet the standard, an RS-232 driver's output must be at least 5V with a 3,000-ohm load. From this, we can use Ohm's law to deduce that each output can source at least 1.6 milliampere at 5V. In practice, most RS-232 outputs exceed the minimum, but staying within the specification will ensure that a circuit will work on any port. Using Signals as a Power Source Figure 6-7 shows ways of using RS-232 outputs as a power source. When in the On state, RTS and DTR are between +5 and +15V. To set the signals to On in Visual Basic, set MSComm's RTSEnable and DTREnable properties to True. Figure 6-7A shows a simple unregulated output. When an output is positive, it can serve as a positive voltage source. To double the output current, tie two lines together as shown, with a 1N5819 Schottky diode in each line. This prevents current from feeding back into the interface if the voltages differ. You can use any rectifier diodes, but Schottkys have a lower forward voltage than other silicon diodes. You can even use the TD line as a power source by setting the Break signal, but of course this prevents you from using the line for data. However, this technique might be useful if you're using the port as a synchronous interface, using handshaking lines for the clock and data. Regulating the Voltage Adding a high-efficiency regulator results in a steady output voltage with little wasted power. Figure 6-7B shows a regulated 5V output using the MAX667 low-dropout, linear regulator. The input can be as high as 18V, and it needs to be just 10 millivolts greater than the output, so it will work with most ports. The regulator's quiescent current is under 100 microamperes with a load of several milliamperes. For a circuit that will work even if the RS-232 output drops below 5V, use the MAX770, which is a switching regulator that has a 5V output with an input between 2V and 16V. The '770 requires several external components, including an inductor and output transistor. If you need only one or a few supplies, Maxim has an inexpensive evaluation kit containing a PC board with all of the components installed. Another option for port power is to use a lower regulated voltage, either by connecting voltage-divider resistors between Vout, Set, and Gnd as described in the MAX667's data sheet, or by using a regulator with a lower fixed output such as the 3V MAX689. Because you can count on getting at most a few milliamperes from the port, use care in choosing components that will use port power. Use the lowest-power components you can find, and use a 3V supply if possible.

Reviews:

Outstanding! "The" authority on COMM programming: Once again, Jan Axelson has done an outstanding job of taking a difficult subject and explaining it to those of us who aren't rocket scientists. The source code works wonderfully and unlike many other books, she provides real-world examples. My only complaint is that she left out examples for the popular PowerBASIC compilers for Windows (although the VB code ports fairly easily).

Excellent companion to the PC parallel port: Another excellent book form Jan Axelson. Superbly written. Easy to understand lucid and still technically a completely reliable reference. Once the basics have been mastered one can develop a variety of applications (particularly control circuits). Equally useful for beginners, students and professionals. Good support material provided on auther's web-site. This book makes a good companion of the similar book on Parallel port interface by the same auther. Students looking for good projects will find this book extremely useful. Even self study is possible for a newcomer. Highly recommended.

Quite disapponting....This book can give you basic knowledge which is helpful for new VB programmer on serial port communication. However, if you are trying to find sth related to RS485 communication, you will be disappointed becasue the example is no longer suitable nowadays. Try technical notes from device manufacturer on the web is a better solution. Not worth it, This book is quite disappointing. It's coverage is both narrow and shallow. If you're after some code to do serial programming from Visual Basic it's probably ok, but any different or deeper than that, you're better off with what you'll find on Google.

A good source of info, but not for the beginner: This book is very complete indeed, but it assumes you already know a fair bit about electronic circuitry. As a computer programmer with little electronics experience, I first had to read up on basic electronics. Also, some sections could have been easier to understand if there was more supporting details or examples. However, the book did answer most of my questions about the serail port and I was able to complete my programming project on time. I would rate this book a 3.5 to 4.0

A Complete Reference: This is a superb book to help you interface a hardware device that you built, to the PC's serial port. But it is much more than that. It also shows how to network multiple computers using the serial port (hence creating your own network!). In addition, it also has details on how to interface some microcontroller based designs to the serial port as well. The author does focus on Visual Basic to access the ports but gives clear pointers as to how to use other methods to access the serial port ( including C ). The disk even has dll's you can use for direct port access even though this is forbidden under WinNT/2000, unless you use the function CreateFile(). All and all, I thought I got more for my money than I could've hoped for. Thank you Jan Axelson!