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About This Manual

©

 National Instruments Corporation

xiii

Serial for Windows NT

Related Documentation

The following documents contain information that you may find helpful
as you read this manual:

• 

ANSI/EIA-232-D Standard, Interface Between Data Terminal
Equipment and Data Circuit-Terminating Equipment Employing
Serial Binary Data Interchange

• 

EIA/RS-422-A Standard, Electrical Characteristics of Balanced
Voltage Digital Interface Circuits

• 

EIA-485 Standard, Standard for Electrical Characteristics of
Generators and Receivers for Use in Balanced Digital Multipoint
Systems

• 

Microsoft Win32 Software Developer Kit, Online Documentation for
Win32 Overviews, Win32 Reference, and Microsoft Windows NT
System Guide, Microsoft Corporation

• 

NS16550AF Universal Asynchronous Receiver/Transmitter with
FIFOs, National Semiconductor

Customer Communication

National Instruments wants to receive your comments on our products
and manuals. We are interested in the applications you develop with our
products, and we want to help if you have problems with them. To
make it easy for you to contact us, this manual contains comment and
configuration forms for you to complete. These forms are in Appendix E,
Customer Communication, at the end of this manual.

Содержание PCMCIA-232

Страница 1: ...Getting Started with Your Serial Hardware and Software for Windows NT June 1997 Edition Part Number 321572A 01 Copyright 1997 National Instruments Corporation All Rights Reserved ...

Страница 2: ...66 Austria 0662 45 79 90 0 Belgium 02 757 00 20 Canada Ontario 905 785 0085 Canada Québec 514 694 8521 Denmark 45 76 26 00 Finland 09 725 725 11 France 01 48 14 24 24 Germany 089 741 31 30 Hong Kong 2645 3186 Israel 03 5734815 Italy 02 413091 Japan 03 5472 2970 Korea 02 596 7456 Mexico 5 520 2635 Netherlands 0348 433466 Norway 32 84 84 00 Singapore 2265886 Spain 91 640 0085 Sweden 08 730 49 70 Swi...

Страница 3: ... USE OF PRODUCTS OR INCIDENTAL OR CONSEQUENTIAL DAMAGES EVEN IF ADVISED OF THE POSSIBILITY THEREOF This limitation of the liability of National Instruments will apply regardless of the form of action whether in contract or tort including negligence Any action against National Instruments must be brought within one year after the cause of action accrues National Instruments shall not be liable for ...

Страница 4: ...s Class A digital apparatus meets all requirements of the Canadian Interference Causing Equipment Regulations Cet appareil numérique de la classe A respecte toutes les exigences du Règlement sur le matériel brouilleur du Canada Class B Federal Communications Commission This equipment has been tested and found to comply with the limits for a Class B digital device pursuant to part 15 of the FCC Rul...

Страница 5: ...cables to test this device and provides them for sale to the user The use of inferior or nonshielded interface cables could void the user s authority to operate the equipment under the FCC rules If necessary consult National Instruments or an experienced radio television technician for additional suggestions The following booklet prepared by the FCC may also be helpful Interference to Home Electro...

Страница 6: ...l Hardware Overview 1 2 NI Serial Software Overview 1 4 Optional Programming Tools 1 4 Using the Serial Hardware with Other National Instruments Products 1 5 Chapter 2 Installation and Verification Installing the Microsoft PnP ISA Enabler Driver 2 1 Install the NI Serial Software 2 1 Install the Serial Hardware 2 3 Install the PCMCIA Card 2 3 Select Resources for the PCMCIA Card 2 4 Install the AT...

Страница 7: ...5 2 3 4 AT Boards Shared IRQ 3 5 AT Boards Non Shared IRQ 3 7 Chapter 4 Using Your Serial Hardware Advanced Transceiver Control AT 485 PCMCIA 485 4 1 Four Wire Mode 4 2 Two Wire Mode DTR with Echo 4 2 Two Wire Mode DTR Controlled 4 2 Two Wire Mode TXRDY Auto Control 4 2 Setting the Transceiver Control Mode 4 3 Setting the Transceiver Mode with DeviceIoControl 4 3 General Programming Requirements 4...

Страница 8: ...emoving the Hardware Information C 1 Uninstalling the NI Serial Software C 2 Appendix D Troubleshooting and Common Questions Missing Serial Port in the niports List D 1 Resolving Resource Conflicts D 1 Troubleshooting Diagnostic Messages D 2 Common Questions D 3 Appendix E Customer Communication Glossary Figures Figure 2 1 Add Remove Programs Properties Dialog Box 2 2 Figure 2 2 NI Serial Setup Sc...

Страница 9: ... 7 Figure B 6 Null Modem Cabling in a DTE to DCE Interface B 7 Figure C 1 Selecting an Interface to Uninstall C 2 Figure C 2 Add Remove Programs Properties Dialog Box C 3 Figure C 3 Uninstallation Results C 4 Tables Table 2 1 DB 9 Pin Descriptions 2 9 Table 2 2 10 Position Modular Jack Pin Descriptions 2 10 Table 2 3 DB 25 Pin Descriptions 2 11 Table 4 1 Transceiver Control Modes 4 1 Table 4 2 Tra...

Страница 10: ...re Chapter 2 Installation and Verification contains instructions to help you install the serial hardware NI Serial software and cables Chapter 3 Configuration contains instructions to help you view or change the communication port settings Chapter 4 Using Your Serial Hardware describes how to set the hardware transceiver control mode for your RS 485 interfaces and lists some general programming re...

Страница 11: ...e Fonts options from the last dialog box bold Bold text denotes the names of menus menu items parameters dialog boxes or dialog box buttons or options bold italic Bold italic text denotes a note caution or warning bold monospace Bold text in this font denotes the messages and responses that the computer automatically prints to the screen italic Italic text denotes emphasis a cross reference or an ...

Страница 12: ...Receivers for Use in Balanced Digital Multipoint Systems Microsoft Win32 Software Developer Kit Online Documentation for Win32 Overviews Win32 Reference and Microsoft Windows NT System Guide Microsoft Corporation NS16550AF Universal Asynchronous Receiver Transmitter with FIFOs National Semiconductor Customer Communication National Instruments wants to receive your comments on our products and manu...

Страница 13: ...y describes the serial hardware and the NI Serial software How to Use This Manual Yes No Chapter 2 Chapter 3 Write Application Program Passes Gather What You Need to Get Started Chapter 1 Install the NI Serial Software Learn About Transceiver Control Modes Review Programming Requirements Install the Serial Hardware Configure the Serial Port Verify the Installation Connect the Cables Troubleshootin...

Страница 14: ... Microsoft Windows NT version 4 0 or higher installed on your computer If you have a four port isolated interface you also need a 10 position modular jack to DB 9 cable which is included in your kit Optional Equipment Call National Instruments for more information about the following optional equipment DB 9 RS 485 termination connector AT 485 and PCMCIA 485 interfaces only 10 position modular jack...

Страница 15: ...anual references to AT 232 and AT 485 generally refer to either version The isolated AT 232 and AT 485 boards are designed for applications in harsh environments The isolated ports provide reliable communication in situations where non isolated ports could not because of ground loops from different ground levels or high common mode voltage induced on the lines in noisy environments The isolation b...

Страница 16: ...ns for more information about software specifications and recommended operating conditions The NI Serial software includes the following components Device driver Diagnostic test Configuration utility Optional Programming Tools Your kit includes the NI Serial software for Windows 95 and Windows NT In addition you can order the LabWindows CVI or LabVIEW software from National Instruments LabWindows ...

Страница 17: ...bVIEW also includes an extensive instrument driver library For more information about LabWindows CVI and LabVIEW contact National Instruments Using the Serial Hardware with Other National Instruments Products You can use standard serial I O functions in LabVIEW and LabWindows CVI with any National Instruments serial interface once you have installed the hardware and software If you already have La...

Страница 18: ...install the Plug and Play hardware you must install the PnP ISA Enabler driver included on your Windows NT 4 0 CD ROM Complete the following steps to install the driver 1 Locate the Pnpisa inf file in the Drvlib Pnpisa X86 folder on the Windows NT 4 0 CD ROM 3 Right click on the Pnpisa inf file then click Install on the menu that appears 3 Restart the computer Install the NI Serial Software Before...

Страница 19: ...ars Figure 2 1 Add Remove Programs Properties Dialog Box You can use this same applet to uninstall the NI Serial software at a later time if you want to Refer to Appendix C Uninstalling the Serial Hardware and Software for more information 4 Click on the Install button 5 Insert the NI Serial Software for Windows 95 and Windows NT Setup Disk and click on the Next button to proceed 6 The software in...

Страница 20: ...u can exit the setup where appropriate by clicking on the Cancel Note This installation backs up the Microsoft Windows NT serial driver serial sys to serial bak and then overwrites serial sys serial sys is located in the Windows NT system32 drivers directory The software is installed Proceed to the next section Install the Serial Hardware Install the Serial Hardware Install the PCMCIA Card To inst...

Страница 21: ... to connect the cable PCMCIA Socket Portable Computer NA TI ON AL IN ST RU ME NT S The Soft war e is the Inst rum ent PCMCIA Serial Cable IN S E R T C A R D Figure 2 3 Inserting a PCMCIA Serial Card Proceed to the next section Select Resources for the PCMCIA Card Select Resources for the PCMCIA Card Complete the following steps to select resources for your PCMCIA card 1 Select Start Settings Contr...

Страница 22: ... to install an AT serial board Note If you are installing an AT 485 you may need to adjust the value of the bias resistors depending on your application For more information refer to Appendix B Serial Port Information 1 Turn off your computer Keep the computer plugged in so that it remains grounded while you install the AT serial board 2 Remove the top or side cover of the computer 3 Remove the ex...

Страница 23: ...your serial hardware In each dialog box make sure that Windows Default Driver is selected and click on OK 8 The serial configuration software displays a PnP Port Configuration dialog box Select a nonconflicting base I O address and IRQ setting for the port card and click on OK For more information on selecting resources for your post card refer to the Resource Settings section of Chapter 3 Configu...

Страница 24: ...ort PORT2 refers to the next port down and so on On newer hardware the physical ports are labeled PORT1 PORT2 and so on When you have finished verifying the driver installation and physical port proceed to the next section Run the Diagnostic Test Run the Diagnostic Test To verify and test the installation run the diagnostic program that came with your NI Serial software The diagnostic program veri...

Страница 25: ...ated four port kits You can also use a DB 25 connector with the four port AT serial boards by ordering the 10 position modular jack to DB 25 cable from National Instruments Note To achieve the specified isolation voltage for four port isolated AT boards use ONLY the 10 position modular jack to DB 9 cable included in your four port isolated AT serial board kit Figure 2 5 and Table 2 1 give the pin ...

Страница 26: ...XD CTS HSI Pin 3 TXD RTS HSO Pin 4 DTR RXD Pin 5 GND RXD Pin 6 DSR CTS HSI Pin 7 RTS RTS HSO Pin 8 CTS TXD Pin 9 RI TXD These signals are not supported by the isolated 232 ports Figure 2 6 and Table 2 2 give the pin locations and descriptions of the 10 position modular jack which is found on the four port AT serial board Pin 10 Pin 1 Figure 2 6 10 Position Modular Jack Pin Locations ...

Страница 27: ...RXD CTS HSI Pin 8 TXD RTS HSO Pin 7 DTR RXD Pin 6 GND RXD Pin 5 DSR CTS HSI Pin 4 RTS RTS HSO Pin 3 CTS TXD Pin 2 RI TXD Pin 1 No Connect No Connect These signals are not supported by the isolated 232 ports Figure 2 7 and Table 2 3 give the pin locations and descriptions of the DB 25 connector which is on the optional 10 position modular jack to DB 25 cable PIN 1 PIN 25 PIN 13 PIN 14 Figure 2 7 DB...

Страница 28: ...DCD GND Pin 20 DTR RXD Pin 22 RI TXD Pins not listed in this table are No Connect These signals are not supported by the isolated 232 ports Figure 2 8 shows how to connect the cables when you install a four port version of the AT serial board AT Serial Board Additional Serial Cable Additional Serial Cable 10 position modular jack to DB 9 cable 10 position modular jack to DB 25 cable 485 Terminator...

Страница 29: ...ect an RS 485 data acquisition device to a port on your AT 485 using half duplex communication you need a single twisted pair of wires At the AT 485 you should connect the TXD and RXD signals pins 8 and 4 on a DB 9 connector pins 5 and 20 on a DB 25 connector together and to one wire You should connect the other end of this wire to both the TXD and RXD signals on the data acquisition device You us...

Страница 30: ...Port Settings The serial configuration utility is fully integrated with the Windows NT Control Panel You can use it to examine or modify the configuration of the serial port Follow these steps to configure the serial port 1 Select Start Settings Control Panel and double click on the niports icon A list of National Instruments ports appears as shown in Figure 3 1 Figure 3 1 niports Configuration Ut...

Страница 31: ...ttings dialog box to view or configure the resources for the port Refer to the Resource Settings section later in this chapter for more information 5 Click on Delete to remove the port 6 Click on Add to configure resources for a new PCMCIA card General Port Settings This section describes the options you can set in the General Port Settings dialog box shown in Figure 3 2 Figure 3 2 General Port Se...

Страница 32: ...ed control to enable or disable the FIFO buffers on the serial port FIFO buffers are present on the 16550 compatible UARTs one for the transmitter and one for the receiver Resources Click on the Resources button to display the resource configuration dialog box for the port For more information on resource configuration refer to the next section Resource Settings Resource Settings The following sec...

Страница 33: ...or the PCMCIA 485 Base I O Address The base I O address assigned to the port IRQ The IRQ assigned to the port PCMCIA 232 2 PCMCIA 485 2 These cards require two base I O settings one for each port and they share an IRQ Figure 3 4 shows the resource configuration dialog box for a PCMCIA 485 2 The PCMCIA 232 2 dialog box is similar ...

Страница 34: ...ote When you select resources for the PCMCIA cards use the Microsoft Windows NT diagnostics utility to make sure that the resources have not been assigned to any other device This utility displays a list of I O port addresses and IRQ levels that are currently being used in your system AT Boards Shared IRQ Figure 3 5 shows the PnP Port Configuration dialog box for an AT 232 4 with shared IRQ The di...

Страница 35: ... Output Range Each Input Output Range listing displays the I O address ranges assigned to the corresponding port on the board Interrupt Request The IRQ shared between the ports on the board Note The niports utility informs you if your resources conflict with the resources of any other interface in the system It does not check for conflicts with ports on the same board Make sure to assign resources...

Страница 36: ...put Range The base I O address range assigned to the port IRQ The IRQ assigned to the port Note The niports utility informs you if your resources conflict with the resources of any other interface in the system It does not check for conflicts with ports on the same board Make sure to assign resources that do not conflict with those assigned to another port on the same board Note If you are unable ...

Страница 37: ...re flow control to enable and disable your transmitters and receivers to work on different bus topologies Table 4 1 lists the status of the transmitters and receivers under each of the transceiver control modes Table 4 1 Transceiver Control Modes Mode Transmitter Receiver Four wire mode Always enabled Always enabled Two wire mode DTR with echo Enabled with DTR unasserted Always enabled Two wire mo...

Страница 38: ...two wire DTR with echo mode Use this mode in half duplex systems where the DTR line must control the transmitter Although this mode uses the same method as the DTR with echo mode to control the transmitter the hardware automatically disables the receiver whenever the transmitter is enabled Thus you do not receive packets that you have transmitted Two Wire Mode TXRDY Auto Control In this mode the h...

Страница 39: ...r wire mode 0x00 Two wire mode DTR with echo 0x01 Two wire mode DTR controlled 0x02 Two wire mode TXRDY auto control 0x03 The scratch register is located at offset 7 from the base address of the port For example if COM2 were located at base address 0x3F8 and you wanted to set the AT 485 board to two wire mode with DTR control you would write a 0x02 to I O address 0x3FF The AT 485 board would immed...

Страница 40: ...quirements Once installed the NI Serial software is integrated into the standard Windows NT communications software NI serial ports are used like any other Windows NT communications COM port Windows NT has standard communication functions for use within either 16 bit Win16 applications or 32 bit Win32 applications Setting the Maximum Baud Rate for a 16 Bit Application To select 115 200 baud from a...

Страница 41: ...tandard Microsoft Windows serial communication functions For information about Microsoft Windows serial communication functions refer to the Win32 Software Development Kit Online help for Win32 Overviews and Win32 Reference If you have LabVIEW or LabWindows and want to use it with your serial hardware refer to your LabVIEW or LabWindows documentation for information about serial I O functions ...

Страница 42: ...ns Hardware Specifications Table A 1 Physical Characteristics of the Two Port AT Serial Boards Characteristic Specification Dimensions 10 67 by 16 51 cm 4 2 by 6 5 in I O Connector DB 9 Power Requirement from PC AT I O channel AT 485 2 AT 232 2 AT 485 2 Shared IRQ AT 232 2 Shared IRQ 5 VDC 390 mA Typical 510 mA Maximum 5 VDC 260 mA Typical 340 mA Maximum 5 VDC 140 mA Typical 180 mA Maximum 5 VDC 7...

Страница 43: ...ated 5 VDC 220 mA Typical 260 mA Maximum 5 VDC 160 mA Typical 200 mA Maximum Table A 3 Physical Characteristics of the Four Port AT Serial Boards Characteristic Specification Dimensions 10 67 by 16 51 cm 4 2 by 6 5 in I O Connector 10 position modular jack Power Requirement from PC AT I O channel AT 485 4 AT 232 4 AT 485 4 Shared IRQ AT 232 4 Shared IRQ 5 VDC 160 mA Typical 200 mA Maximum 5 VDC 11...

Страница 44: ...l 360 mA Maximum 5 VDC 280 mA Typical 320 mA Maximum The four port isolated AT serial board requires cables which are included in your kit to convert the 10 position modular jack to a DB 9 connector Use only the types of cables provided in your kit Table A 5 Physical Characteristics of the PCMCIA Serial Cards Characteristic Specification Dimensions 85 6 cm by 54 0 cm by 5 0 mm 3 370 by 2 126 by 0 ...

Страница 45: ...sing Storage Environment Temperature Relative Humidity 20 to 70 C 5 to 90 noncondensing EMI AT Serial AT Serial Isolated PCMCIA Serial FCC Class B Certified FCC Class A Verified FCC Class A Verified Software Specifications Table A 7 Software Characteristics Characteristic Specification Maximum Serial Transfer Rate 115 200 bps Space Required for NI Serial Software 1 MB Actual speed may vary conside...

Страница 46: ...rial communication up to distances of 50 ft and with data rates up to 20 kb s However because of improvements in line drivers and cabling you can often increase the actual performance of the bus past the limitations on speed and distance recommended in the specification RS 422 RS 422 as specified in the EIA RS 422 A Standard Electrical Characteristics of Balanced Voltage Digital Interface Circuits...

Страница 47: ...d by working with half duplex bus architectures Unlike the RS 422 standard RS 485 addresses the issue of using multiple transmitters on the same line RS 485 defines the electrical characteristics necessary to ensure adequate signal voltages under maximum load short circuit protection and the ability to withstand multiple drivers driving conflicting signals at the same time Table B 1 lists the feat...

Страница 48: ...e devices use a separate wire or pair of wires for simultaneous transmission in each direction Thus there is no need to switch between transmitting and receiving In a differential serial bus for example RS 422 or RS 485 a half duplex system can transmit and receive over the same twisted pair of wires Thus half duplex communication is often referred to as two wire communications Likewise full duple...

Страница 49: ...Duplex A typical half duplex multidrop bus architecture also involves a master slave protocol In a half duplex system all transmitters and receivers are connected to the same transmission line A half duplex system is often referred to as a two wire system Figure B 2 shows a typical half duplex system MASTER Slave 1 Slave 2 Slave n Tx Tx Rx Rx Tx Rx Tx Rx Figure B 2 Typical Half Duplex System ...

Страница 50: ...85 termination connector that contains embedded terminating resistors for easy termination Figure B 3 shows a multidrop network using terminating resistors MASTER Slave 1 100 Ω Slave 2 Slave n 100 Ω Tx Tx Rx Tx Rx Tx Rx Rx Figure B 3 Multidrop Network Using Terminating Resistors Bias Resistors A transmission line enters an indeterminate state if no nodes are transmitting on it This indeterminate s...

Страница 51: ...o effectively achieve the same result DTE vs DCE Data Terminal Equipment DTE and Data Communications Equipment DCE were the terms used in the RS 232 specification for the types of equipment on either end of a serial connection A DCE is called Data Circuit Terminating Equipment in Revision D of the RS 232 specification In general DTE and DCE refer to computer equipment and modems respectively Becau...

Страница 52: ... are wired together using a straight through cable one transmitter is connected to the other transmitter and one receiver is connected to the other receiver In this setup no transmissions can occur Thus these applications must use a cabling scheme that connects the transmitter on one device to the receiver on the other device and vice versa This method is known as null modem cabling because it rep...

Страница 53: ... NI Serial software Removing the Hardware Information Before physically removing the serial hardware from the computer you must remove the hardware information from the Windows NT Control Panel Follow these steps to uninstall the hardware 1 Double click on the niports icon under Start Settings Control Panel 2 Select the port to remove from the list of ports as shown in Figure C 1 ...

Страница 54: ...installing the software you should remove all serial port information from the Windows NT Control Panel as described in the previous section You do not need to shut down Windows NT before uninstalling the software Complete the following steps to remove the NI Serial software 1 Select Start Settings Control Panel 2 Double click on the Add Remove Programs icon in the Control Panel to launch the Add ...

Страница 55: ...T Figure C 2 Add Remove Programs Properties Dialog Box 3 Select the serial software you want to remove and click the Add Remove button The uninstall program runs and removes all folders utilities and registry entries associated with the NI Serial software Figure C 3 shows the results of a successful uninstallation ...

Страница 56: ...r Windows NT C 4 National Instruments Corporation Figure C 3 Uninstallation Results 4 Shut down Windows NT power off your computer and remove your serial interfaces now If you want to reinstall the hardware and software refer to Chapter 2 Installation and Verification ...

Страница 57: ... the AT boards without the Microsoft PnP ISA Enabler driver For more information refer to the Installing the Microsoft PnP ISA Enabler Driver section of Chapter 2 Installation and Verification Resolving Resource Conflicts Resource conflicts occur when your system contains hardware that is configured to use the same resources as your serial interface The serial driver detects some resource conflict...

Страница 58: ...llation and Verification to follow these troubleshooting steps 1 Verify the hardware resources 2 Verify that the National Instruments serial driver is installed 3 If either the serial hardware or serial sys file is missing reinstall the hardware and software Lesser number of ports found than expected If this error message appears refer to Chapter 2 Installation and Verification to follow these tro...

Страница 59: ...ol Panel to display a list of installed ports What do I do if the diagnostic test fails with an error Refer to the troubleshooting sections of this manual for specific information about what might cause the test to fail How can I determine which port is associated with COMx Refer to the section Determine Which Physical Port is Associated with COMx in Chapter 2 Installation and Verification How can...

Страница 60: ...me Electronic Services Bulletin Board Support National Instruments has BBS and FTP sites dedicated for 24 hour support with a collection of files and documents to answer most common customer questions From these sites you can also download the latest instrument drivers updates and example programs For recorded instructions on how to use the bulletin board and FTP services and for BBS automated inf...

Страница 61: ...ional Instruments office in your country contact the source from which you purchased your software to obtain support Telephone Fax Australia 03 9879 5166 03 9879 6277 Austria 0662 45 79 90 0 0662 45 79 90 19 Belgium 02 757 00 20 02 757 03 11 Canada Ontario 905 785 0085 905 785 0086 Canada Quebec 514 694 8521 514 694 4399 Denmark 45 76 26 00 45 76 26 02 Finland 09 725 725 11 09 725 725 55 France 01...

Страница 62: ... Display adapter ________________ Mouse ____ yes _____ no Other adapters installed _____________________________ Hard disk capacity ________ MB Brand ____________________________________________ Instruments used __________________________________________________________________ National Instruments hardware product model _____________________ Revision ____________ Configuration ___________________...

Страница 63: ...ely before contacting National Instruments for technical support helps our applications engineers answer your questions more efficiently National Instruments Products Serial Hardware and Revision Number AT 232 Board Revision Two Port Four Port or AT 485 Board Revision Two Port Four Port or PCMCIA 485 Card Revision One Port Two Port or PCMCIA 232 Card Revision One Port Two Port NI Serial Software R...

Страница 64: ...uency Type of Monitor Card Installed Windows Version Application Programming Language Microsoft C Visual Basic for Windows Number of Serial Ports in System Built In Adapter Cards Other Boards in System Base I O Address of Other Boards Interrupt Level of Other Boards ...

Страница 65: ..._________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ __...

Страница 66: ... C Celsius COM Computer Output Microform DB xx subminiature D connector where xx is the number of pins DCE Data Communications Equipment or Data Circuit Terminating Equipment DMA direct memory access DTE Data Terminal Equipment DTR Data Terminal Ready where the overscore denotes that the signal is active low EIA Electronic Industries Association EMI electromagnetic interference FCC Federal Communi...

Страница 67: ...es I O input output IRQ interrupt request ISA Industry Standard Architecture m meters MB megabytes of memory PC personal computer RAM random access memory RX Receive s seconds TX Transmit TXRDY Transmit Ready where the overscore denotes that the signal is active low UART universal asynchronous receiver transmitter V volts VDC volts direct current ...

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