Visual Basic Programmer's Guide to Serial Communications

INCLUDES .NET! Also includes VB5, VB6, and eVB for Windows CE. Add serial communications to your Visual Basic applications using Custom Controls and the Windows API. Includes VB5 and VB6! Here is the information you that you need to use modems and direct serial connections (including RS-232, RS-422 and RS-485) for almost any purpose. Richard Grier uses his many years of experience to guide you through the process, while providing the insight that you will need to extend and adapt the ideas that he presents to your own projects. Make your serial communications programs reliable. Learn how to debug communications problems. Resources galore!

A Quick Preview Of The Book And Disk Content
Chapter 1 covers serial communications, Windows, the PC hardware that is used, and flow-control. Error-corrected file transfers and terminal emulation are covered next. Chapter 2 covers modems and serial standards. More than 40 of the most common questions about modems are answered. Serial hardware standards are discussed, and various RS-232 null-modems are illustrated. RS-422 and RS-485 are discussed, with code fragments presented for RS-485. Chapter 3 discusses the details of the Windows communications API, including the Telephony API. Chapter 4 discusses the MSCOMM custom control. The versions for VB2 through VB5 are covered, along with programming concepts for each. Here is where we start to see some practical program examples to illustrate the use of MSCOMM. There is a program included called LOGGER. This program illustrates how to use MSCOMM to communicate with a (DVM) Digital Volt Meter. The ideas that are conveyed with this program include how to implement a communications protocol, in this case one that has been designed by an electronic instrument manufacturer. The last MSCOMM program is a Global Positioning Satellite receiver program. It illustrates implementation of a serial protocol called NMEA-0183. The receiver program synchronizes your computer to the GPS receiver time and date, and provides highly accurate location (latitude and longitude). Several other programs (applets) are included to illustrate various points. Chapter 5 goes into the Windows API. First the Windows16 API, with a very simple dumb terminal program. You might choose to use the Windows API if you don't have VB Professional version, so you don't have MSCOMM. If you don't want to upgrade, or to purchase a commercial communications add-on, this will show you what you need to know. Also included is a program that uses the API to overcome the maximum speed limitation (19.2K bps) of 16-bit versions of MSCOMM. Next discussed is the Windows 32 Communications API. The 32-bit API is similar to the 16-bit API, but there are critical differences. Last is TAPI (the Telephony API). A simple Windows 95 dialer is shown, and other uses, and limitations of TAPI are discussed. Chapter 6 is an overview of a variety of commercial communications add-ons for Visual Basic. The Crescent PDQComm, MicroHelp Communication Library, Sax Comm Objects, SilverWare SilverComm, MagnaCarta CommTools, and Crystal CrystalCOMM are discussed. Three programs are provided. One is a Simple Host, the other a Simple Remote. These show dialing and automatic error-corrected file transfers. These programs use the PDQComm custom control. The third program uses the Crescent PDQTapi custom control to provide a TAPI interface for the Simple Remote program. Chapter 7 discusses paging. Numeric paging is shown, and the and its limitations are discussed. Alphanumeric paging (AlphaPaging) is the real forte of this chapter. Two add-ons for Visual Basic are covered. Significa Software's custom controls are discussed, and a program is included that uses Rob Tanner's PowerPage DLLs (the DLLs are included on the disk) illustrates the process. Chapter 8 examines the use of direct I/O port manipulation to do things that cannot be done using more conventional API methods. This requires that you understand the physical I/O structure of your PC. Four methods are discussed. The first uses VBASM.DLL (included) to access PC I/O ports on a system using a 16-bit version of Visual Basic. The second uses WIN95WIN95IO.DLL to do the same using a 32-bit version of Visual Basic. Two programs are included that monitor the status of the Carrier Detect bit in the UART. This allows a Visual Basic program to record the total connect time of another Windows Program. A third program is used to overcome the maximum speed limitation (19.2K bps) of MSCOMM32.OCX, furnished with VB4. Two commercial products, Tetradyne Hardware OCX and BlueWater Systems WinRT OCX, are discussed that allow you to access hardware directly under both Windows 95 and Windows NT. A demonstration program, using Tetradyne Hardware OCX is presented that allows a program to force DTR false, thus causing a modem disconnect, on a comport that is opened by another application. A shareware kernel-mode driver, called TINYPORT is included on the disk, and is described. This driver provides port I/O under Windows NT Chapter 9 is important. Debugging communications applications can be hard. Here are discussed both hardware and software methods for debugging your applications. Techniques for optimizing your code and tips to increase its reliability are presented. The use and utility of telephone line simulators are discussed. Last, debugging serial port hardware problems is discussed. Appendix A provides resources. Contact information is provided for all of the products that were mentioned in the book. Lots of additional contact information is provided for companies that offer products or services that may be useful, but that couldn't be discussed in detail. Appendix B is a VT100 terminal emulator that uses the Windows 16-bit API. It includes XMODEM file transfers and scripting. Appendix C is the complete NMEA-0183 protocol, used in the GPS receiver program. Appendix D details the I/O port description of 8250 and 16550AF UARTS. Appendix E is a chart of the ASCII character set. Appendix F is the basic AT modem command set.