Serial Getting Started with Your PCI Serial Hardware and Software for Windows Me/9x PCI Serial for Windows Me/9x September 2000 Edition Part Number 321824E-01
Support Worldwide Technical Support and Product Information ni.
Important Information Warranty The serial hardware is warranted against defects in materials and workmanship for a period of one year from the date of shipment, as evidenced by receipts or other documentation. National Instruments will, at its option, repair or replace equipment that proves to be defective during the warranty period. This warranty includes parts and labor.
Compliance FCC/Canada Radio Frequency Interference Compliance* Determining FCC Class The Federal Communications Commission (FCC) has rules to protect wireless communications from interference. The FCC places digital electronics into two classes. These classes are known as Class A (for use in industrialcommercial locations only) or Class B (for use in residential or commercial locations). Depending on where it is operated, this product could be subject to restrictions in the FCC rules.
• • Connect the equipment into an outlet on a circuit different from that to which the receiver is connected. Consult the dealer or an experienced radio/TV technician for help. Canadian Department of Communications This Class B digital apparatus meets all requirements of the Canadian Interference-Causing Equipment Regulations. Cet appareil numérique de la classe B respecte toutes les exigences du Règlement sur le matériel brouilleur du Canada.
Contents About This Manual Conventions ...................................................................................................................xi Related Documentation..................................................................................................xii Chapter 1 Introduction How to Use This Manual ...............................................................................................1-1 What You Need to Get Started .........................................................
Contents Advanced Port Settings ................................................................................... 3-3 Transceiver Mode ............................................................................. 3-4 Use FIFO Buffers ............................................................................. 3-4 Restore Defaults .............................................................................................. 3-4 Chapter 4 Using Your Serial Hardware General Programming Requirements ......
Contents Figures Figure 2-1. Figure 2-2. Figure 2-3. Figure 2-4. Figure 2-5. Figure 2-6. Figure 2-7. Figure 2-8. Figure 2-9. Figure 2-10. Add/Remove Programs Properties Dialog Box.....................................2-1 NI-Serial Setup Screen ..........................................................................2-2 PCI Serial Board Installation.................................................................2-4 Device Manager Tab for PCI Serial Board Ports ..................................
About This Manual This manual contains instructions to help you install and configure the National Instruments serial hardware and the NI-Serial software for Windows Me/9x. This manual includes information about the PCI-232/2, PCI-232/4, PCI-232/8, PCI-232/16, PCI-485/2, PCI-485/4, and PCI-485/8 boards in both isolated and non-isolated versions. This manual assumes that you are already familiar with Windows Me/9x.
About This Manual monospace bold Bold text in this font denotes the messages and responses that the computer automatically prints to the screen. This font also emphasizes lines of code that are different from the other examples. PCI serial boards PCI serial boards refers to all port versions of the PCI serial boards.
1 Introduction This chapter explains how to use this manual, lists what you need to get started and optional equipment you can order, and briefly describes the serial hardware and the NI-Serial software.
Chapter 1 Introduction What You Need to Get Started Before you install your serial hardware and the NI-Serial software, make sure you have all of the following items: ❑ Windows Me/9x installed on your computer ❑ One of the following serial boards, which is included in your kit: – PCI-232 (two-, four-, eight-, or sixteen-port) – PCI-485 (two-, four-, or eight-port) – PCI-232 isolated (two- or four-port) – PCI-485 isolated (two- or four-port) ❑ CD, NI-Serial Software for Windows 2000/NT/Me/9x, whic
Chapter 1 Introduction Additionally, the PCI serial boards are available in a two-port version (PCI-232/2 and PCI-485/2), a four-port version (PCI-232/4 and PCI-485/4), an eight-port version (PCI-232/8 and PCI-485/8), and a sixteen-port version (PCI-232/16). The two-port versions use DB-9 connectors. The four-port versions use 10-position modular jacks to provide all four connections on a single back panel.
Chapter 1 Introduction NI-Serial Software Overview The NI-Serial software for Windows Me/9x includes a native Windows device driver that provides full interrupt-driven, buffered I/O for multiple COM ports. You can obtain a maximum baud rate of 460.8 KBaud on the PCI-485 and 115.2 KBaud on the PCI-232. You can also use up any number of serial ports under Windows Me/9x. The NI-Serial software also includes a configuration utility, which is fully integrated into the Windows Me/9x Device Manager.
Chapter 1 Introduction Using Your Serial Hardware with LabVIEW and LabWindows/CVI After you install your serial hardware and the NI-Serial software, you can use standard serial I/O functions in LabVIEW and LabWindows/CVI with your serial interface. If you already have LabVIEW or LabWindows/CVI and want to use it with your serial hardware, refer to your LabVIEW or LabWindows/CVI documentation for information about serial I/O functions.
2 Installation and Verification This chapter describes how to install the NI-Serial software, serial hardware, and cables, and how to verify the installation. Install the Software Before you install your serial hardware, complete the following steps to install the NI-Serial software for Windows Me/9x: 1. Select Start»Settings»Control Panel. 2. Double-click on the Add/Remove Programs icon. A dialog box similar to the one shown in Figure 2-1 appears. Figure 2-1.
Chapter 2 Installation and Verification 3. Click on the Install button. 4. When prompted, insert the NI-Serial Software for Windows 2000/NT/Me/9x CD, and click on the Next button. 5. When prompted, click on the Finish button to install the program files from floppy disks or CD-ROM. 6. The setup wizard begins with the screen shown in Figure 2-2. Figure 2-2. NI-Serial Setup Screen The setup wizard guides you through the necessary steps to install the NI-Serial software.
Chapter 2 Installation and Verification If no New Hardware Found dialog box appears, refer to the Forcing Windows to Detect Your Hardware section in Appendix C, Troubleshooting and Common Questions. Install the Hardware If you are installing a PCI-485, you might need to adjust the value of the bias resistors, depending on your application. Bias resistors are not available on the eight-port PCI-485. For more information, refer to Appendix A, Serial Port Information.
Chapter 2 Installation and Verification PCI Serial Board PCI Slot Personal Computer Figure 2-3. PCI Serial Board Installation 7. Screw the PCI serial board mounting bracket to the back panel mounting rail of the computer. 8. Replace the cover. 9. Turn on your computer and start Windows Me/9x. 10. Windows Me/9x should automatically detect your hardware and display one or more New Hardware Found dialog boxes. Your operating system (Windows Me/9x) may show the Windows Default Driver option.
Chapter 2 Installation and Verification Verify the Installation Before you verify the installation, keep in mind that the serial ports built into your computer are typically named from COM1 to COM4. Windows Me/9x typically issues port names to the ports on NI serial hardware starting with COM5, COM6, and so on. If not enough resources are available to assign to all the NI serial ports, the port with the higher COMx name is not configured.
Chapter 2 Installation and Verification Figure 2-4 shows the Device Manager tab for serial hardware that is installed properly. Figure 2-4. Device Manager Tab for PCI Serial Board Ports 5. 6. PCI Serial for Windows Me/9x Verify the hardware resources, as follows: a. In the Device Manager tab, under Multi-function adapters, double-click on a serial board. b. Click on the Resources tab.
Chapter 2 Installation and Verification serial hardware, PORT1 refers to the top port, PORT2 refers to the next port down, and so on. 7. Run the diagnostic utility, as follows: select Start»Programs»National Instruments Serial»diagnostics. The diagnostic utility verifies that your serial driver is installed properly, that the configuration of your hardware does not conflict with anything else in your system, and that the serial driver can communicate with your hardware correctly.
Chapter 2 Installation and Verification DB-9 Connector Figure 2-5 and Table 2-1 give the pin locations and descriptions of the DB-9 connector, which is on the two-port PCI serial board, the 10-position modular jack to DB-9 cable, the cable adapter for the eight-port board, and the DB-9 connectors to the sixteen-port breakout box. PIN 5 PIN 9 PIN 6 PIN 1 Figure 2-5. DB-9 Connector Pin Locations Table 2-1.
Chapter 2 Installation and Verification Modular Jack Connector Figure 2-6 and Table 2-2 give the pin locations and descriptions of the 10-position modular jack, which is on the four-port PCI serial board. Pin 1 Pin 10 Figure 2-6. 10-Position Modular Jack Pin Locations Table 2-2.
Chapter 2 Installation and Verification DB-25 Connector 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 13 PIN 25 PIN 14 PIN 1 Figure 2-7. DB-25 Connector Pin Locations Table 2-3.
Chapter 2 Installation and Verification Figure 2-8 shows how to connect the cables when you install a four-port PCI serial board. 10-Position Modular Jack to DB-9 Cable 485 Terminator (485 Boards Only) Additional Serial Cable Serial Board 10-Position Modular Jack to DB-25 Cable Additional Serial Cable Figure 2-8.
Chapter 2 Installation and Verification 68-Pin Connector Figure 2-9 and Table 2-4 give the pin locations and descriptions of the 68-pin connector, which is on the eight-port PCI serial board. PIN 68 PIN 34 PIN 35 PIN 1 Figure 2-9. 68-Pin Connector Pin Locations PCI Serial for Windows Me/9x 2-12 ni.
Chapter 2 Installation and Verification Table 2-4.
Chapter 2 Installation and Verification 100-Pin Connector Figure 2-10 and Table 2-5 give the pin locations and descriptions of the 100-pin connector, which is on the sixteen-port PCI serial board. PIN 100 PIN 51 PIN 50 PIN 1 Figure 2-10. 100-Pin Connector Pin Locations PCI Serial for Windows Me/9x 2-14 ni.
Chapter 2 Installation and Verification Table 2-5.
3 Configuration This chapter describes how to view or change the communication port settings. View or Change Communication Port Settings The serial configuration utility is fully integrated into the Windows Me/9x Device Manager. You can use it to view or change the configuration of your serial ports. To configure a serial port, complete the following steps: 1. Select Start»Settings»Control Panel and double-click on the System icon. 2.
Chapter 3 Configuration Transceiver modes apply to RS-485 interfaces only. For more information about transceiver modes, refer to Chapter 4, Using Your Serial Hardware. Note 5. To save your changes, click on the OK button. To exit without saving the changes, click on the Cancel button. Port Settings Tab In the Port Settings tab, you can change any of the settings by clicking on the arrow button to the right of a field.
Chapter 3 Configuration Bits per Second Bits per second, or baud rate, is the speed for a serial port. Data Bits Data bits is the number of data bits in a single serial byte. Parity Parity is the specification for even, odd, or no parity bits in each transmitted byte. Stop Bits Stop bits is the number of terminating bits on the end of each transmitted serial byte. Flow Control Flow control is a method for temporarily halting the stream of serial bytes to prevent overflow.
Chapter 3 Configuration The following sections describe the advanced port setting options. Transceiver Mode This field shows the transceiver mode in use, and applies only to PCI-485 boards. For more information about transceiver modes, refer to Chapter 4, Using Your Serial Hardware. Use FIFO Buffers FIFO buffers are present on the 16550-compatible UARTs—one for the transmitter and one for the receiver.
4 Using Your Serial Hardware This chapter describes how to set the hardware transceiver control mode for your RS-485 interfaces and lists some general programming requirements. General Programming Requirements The NI-Serial software is fully integrated into the standard Windows Me/9x communications software. NI serial ports are used like any other Windows Me/9x communications (COM) port. Windows Me/9x has standard communication functions for use within either Win16 or Win32 applications.
Chapter 4 Using Your Serial Hardware Table 4-1. Transceiver Control Modes Mode Note Transmitter Receiver Four-wire mode Always enabled Always enabled Two-wire mode: DTR with echo Enabled with DTR unasserted Always enabled Two-wire mode: DTR controlled Enabled with DTR unasserted Enabled with DTR asserted Two-wire mode: TXRDY auto control Enabled with TXRDY asserted Enabled with TXRDY unasserted Signal names with an overscore, such as DTR, indicate that the signal is active low.
Chapter 4 Using Your Serial Hardware Two-Wire Mode: TXRDY Auto Control In this mode, the serial hardware transparently enables the transmitter and receiver in a two-wire system. Use this mode to remove the burden of flow control from your application. By connecting the transmitter to the TXRDY (Transmit Ready) line, the hardware enables the transmitter for each byte to be transmitted.
Chapter 4 Using Your Serial Hardware Table 4-2. Transceiver Mode Control Bytes Transceiver Mode Control Byte Four-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 want to set the PCI-485 board to two-wire mode with DTR control, you would write a 0x02 to address 0x3FF.
Chapter 4 Using Your Serial Hardware Table 4-3.
A Serial Port Information This appendix describes the RS-232, RS-422, and RS-485 standards and explains some of the issues involved with these types of serial communication. Table A-1 lists the features of the RS-232, RS-422, and RS-485 standards. Table A-1.
Appendix A Serial Port Information distances of 50 ft and with data rates up to 20 kbytes/s. However, because of improvements in line drivers and cabling, you can usually increase the actual performance of the bus past the limitations on speed and distance recommended in the specification. RS-422 As specified in the EIA/RS-422-A Standard, Electrical Characteristics of Balanced Voltage Digital Interface Circuits, RS-422 defines a serial interface much like RS-232.
Appendix A Serial Port Information Serial Communication Issues This section explains some serial communication issues, including duplex architectures, termination methods, bias resistors, and types of connecting equipment. Duplex Architectures Duplex refers to the means of bandwidth usage in a serial system. The two common means of bi-directional serial communication are full duplex and half duplex.
Appendix A Serial Port Information Slave 1 MASTER Tx Slave 2 Tx Rx Slave n Tx Rx Rx Tx Rx Figure A-1. Typical Full-Duplex System Half Duplex A typical half-duplex multidrop bus architecture also involves a master-slave protocol. However, 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 A-2 shows a typical half-duplex system.
Appendix A Serial Port Information Termination Because each differential pair of wires is a transmission line, you must properly terminate the line to prevent reflections. A common method of terminating a two-wire multidrop RS-485 network is to install terminating resistors at each end of the multidrop network. If you daisy-chained multiple instruments together, you need a terminating resistor at only the first and last instruments.
Appendix A Serial Port Information Figure A-4 shows a transmission line using bias resistors. +5 620 Bias Resistor A 100 Termination Resistor Rx B 620 Bias Resistor Figure A-4. Transmission Line Using Bias Resistors On the PCI RS-485 2- and 4-port serial cards, there are four user-configurable bias resistors in front of each connector. These resistors are socketed and pre-loaded with 620 Ω resistors.
Appendix A Serial Port Information DTE vs. DCE In the RS-232 specification, DTE (Data Terminal Equipment) and DCE (Data Communications Equipment)1 refer to the types of equipment on either end of a serial connection. In general, DTE and DCE refer to computer equipment and modems, respectively. Because the RS-232 specification mainly involves connecting a DTE directly to a DCE and vice versa, the pinouts are defined so that cabling is simple.
B Uninstalling the Hardware and Software This appendix describes how to uninstall your serial hardware and the NI-Serial software. Uninstall the Hardware Before you physically remove the serial hardware from your system, you must remove the hardware information. To do so, complete the following steps: 1. Select Start»Settings»Control Panel and double-click on the System icon. 2. Select the Device Manager tab and click on the View devices by type button. 3.
Appendix B Uninstalling the Hardware and Software Figure B-1. Selecting an Interface to Uninstall 5. Click on the Remove button. 6. In the Confirm Device Removal dialog box, click on the OK button to remove the hardware information, or click on the Cancel button to cancel your request. Uninstall the Software Before you uninstall the NI-Serial software, you must remove the hardware information from your system, as described in the previous section.
Appendix B Uninstalling the Hardware and Software Figure B-2. Add/Remove Programs Properties Dialog Box 3. © National Instruments Corporation Select the NI-Serial software you want to uninstall, and click on the Add/Remove button. The uninstallation program removes all folders, utilities, and registry entries associated with the NI-Serial software. Figure B-3 shows the results of a successful uninstallation.
Appendix B Uninstalling the Hardware and Software Figure B-3. Successful Uninstallation 4. Shut down Windows Me/9x, turn off your computer, and physically remove the serial interfaces from your system. The uninstallation program only removes items that the setup wizard installed. If you added anything to a directory that the setup wizard created, the uninstallation program does not delete that directory. You must remove any remaining components yourself.
C Troubleshooting and Common Questions This appendix describes how to troubleshoot problems and answers some common questions. Freeing an Interrupt Request Level To free an interrupt request level for your serial port, you must disable the device that is using the interrupt request level. To view the system-wide allocation of interrupt request resources and remove a device, complete the following steps: 1. Select Start»Settings»Control Panel and double-click on the System icon. 2.
Appendix C Troubleshooting and Common Questions Selecting Conflict-Free Resources When the Device Manager indicates a conflict with another device, you can usually correct the problem by manually selecting conflict-free resources. To do so, complete the following steps: 1. Select Start»Settings»Control Panel and double-click on the System icon. 2. Click on the Device Manager tab and click on the View devices by type button. 3. Double-click on the Multi-function adapters icon. 4.
Appendix C 2. Troubleshooting and Common Questions In some versions of Windows Me/9x, in the Device Manager, the Driver tab shows information about the installed driver. Make sure that the National Instruments serial driver is installed for the port. If the serial driver is a Microsoft driver, reinstall the NI-Serial software. For instructions on how to do so, refer to Chapter 2, Installation and Verification. 3. Make sure that the National Instruments serial driver is installed, as follows: a.
Appendix C Troubleshooting and Common Questions Address Test Failed If the address test failed, Interrupt test cannot be performed error message appears, you might have an address conflict with legacy boards in your system. To solve this problem, change the base addresses assigned to your legacy boards and refer to the Resolving Resource Conflicts with Legacy Boards section later in this appendix.
Appendix C 5. Troubleshooting and Common Questions Select the interface that Windows Me/9x did not detect, as shown in Figure C-1. Figure C-1. Ports List in Device Manager 6. Click on the Remove button. 7. Click on the OK button to remove the serial hardware information. 8. Repeat steps 5 through 7 until you have removed all serial interfaces. 9. Click on the Refresh button. 10. Windows Me/9x should automatically detect your hardware and display one or more New Hardware Found dialog boxes.
Appendix C Troubleshooting and Common Questions Common Questions How can I determine which type of serial hardware I have installed? 1. Select Start»Settings»Control Panel and double-click on the System icon. 2. Click on the Device Manager tab and click on the View devices by type button. 3. Double-click on the Ports (COM & LPT) icon to display a list of installed ports. How can I determine which version of the NI-Serial software I have installed? The Read Me file gives the version of the software.
Appendix C Troubleshooting and Common Questions Table C-1. Standard DOS-Based Addresses COM Port Base Address COM1 3f8 COM2 2f8 COM3 3e8 COM4 2e8 How do I change the resources assigned to the serial interface? The PCI serial boards are configured as devices belonging to the multi-function adapters class. The multi-function parent device is listed under the Multi-function adapters icon, and each child device is listed as a port under the Ports (COM & LPT) icon.
D Specifications This appendix describes the characteristics of the serial hardware, the NI-Serial software, along with the recommended operating conditions. Two-Port Boards Dimensions............................................. 10.67 by 14.22 cm (4.2 by 5.6 in.) I/O connector.......................................... DB-9 Power requirement (from PCI channel) PCI-485/2 +5 VDC.................................... 350 mA typical 750 mA maximum PCI-232/2 +5 VDC....................................
Appendix D Specifications Power requirement (from PCI channel) PCI-485/2 +5 VDC ....................................800 mA typical 1300 mA maximum PCI-232/2 +5 VDC ....................................400 mA typical 650 mA maximum Four-Port Boards Dimensions .............................................10.67 by 17.27 cm (4.2 by 6.8 in.) I/O connector1 .........................................10-position modular jack Power requirement (from PCI channel) PCI-485/4 +5 VDC ....................................
Appendix D Specifications Power requirement (from PCI channel) PCI-485/4 +5 VDC.................................... 1000 mA typical 1500 mA maximum PCI-232/4 +5 VDC.................................... 500 mA typical 750 mA maximum Eight-Port Boards Dimensions............................................. 10.67 by14.48 cm (4.2 by 5.7 in.) I/O connector1 ........................................ 68-position, SCSI type connector Power requirement (from PCI channel) PCI-485/8 +5 VDC............................
Appendix D Specifications Environmental Characteristics Operating environment Component temperature ..................0 to 70 °C Relative humidity ............................10 to 90%, noncondensing Storage environment Temperature.....................................–40 to 120 °C Relative humidity ............................5 to 90%, noncondensing EMI .........................................................FCC Class A Verified Software Characteristics Maximum serial transfer rate1 RS-485..............
Technical Support Resources E Web Support National Instruments Web support is your first stop for help in solving installation, configuration, and application problems and questions. Online problem-solving and diagnostic resources include frequently asked questions, knowledge bases, product-specific troubleshooting wizards, manuals, drivers, software updates, and more. Web support is available through the Technical Support section of ni.com NI Developer Zone The NI Developer Zone at ni.
Appendix E Technical Support Resources Worldwide Support National Instruments has offices located around the world to help address your support needs. You can access our branch office Web sites from the Worldwide Offices section of ni.com. Branch office Web sites provide up-to-date contact information, support phone numbers, e-mail addresses, and current events.
Glossary Prefix Meaning Value p- pico- 10 –12 n- nano- 10 –9 µ- micro- 10 – 6 m- milli- 10 –3 k- kilo- 10 3 M- mega- 10 6 G- giga- 10 9 t- tera- 10 12 ° degrees Ω ohms % percent A amperes ANSI American National Standards Institute b bits B bytes baud bits per second bps bits per second C Celsius COM Computer Output Microform; used in reference to a communication port CTS clear to send DB-xx subminiature D connector, where xx is the number of pins © Nation
Glossary DCD data carrier detect DCE data communications equipment or data circuit-terminating equipment DLL dynamic link library DMA direct memory access DSR data set ready DTE data terminal equipment DTR data terminal ready—the overscore denotes that the signal is active low duplex the means of bandwidth usage in a serial system EIA Electronic Industries Association EMI electromagnetic interference FCC Federal Communications Commission FIFO First-In-First-Out ft feet GND ground
Glossary MB megabytes of memory PC personal computer PCI Peripheral Components Interconnect RAM random-access memory RI ring indicator RTS request to send RX receive RXD receive data—the overscore denotes that the signal is active low s seconds SCSI Small Computer Systems Interface TX transmit TXD transmit data—the overscore denotes that the signal is active low TXRDY transmit ready—the overscore denotes that the signal is active low UART Universal Asynchronous Receiver/Transmitt
Index Numerics C 100-pin connector, 2-14 pin descriptions (table), 2-15 pin locations (figure), 2-14 10-position modular jack, 2-9 pin descriptions (table), 2-9 pin locations (figure), 2-9 68-pin connector, 2-12 pin descriptions (table), 2-13 pin locations (figure), 2-12 cable connection, 2-7 changing communication port settings, 3-1 changing resources assigned to serial interface, C-7 common questions, C-6 changing resources assigned to serial interface, C-7 determining port associated with COMx, C-6 de
Index D DTE vs.
Index I null-modem cabling in a DTE-to-DTE interface (figure), A-7 installation getting started, 1-2 PCI serial board installation (figure), 2-4 serial hardware, 2-3 serial software, 2-1 verification, 2-1 verifying hardware installation, 2-5 interrupt request level, C-1 freeing, C-1 introduction, 1-1 isolated four-port boards, D-2 isolated two-port boards, D-1 O optional equipment, 1-2 overview of serial hardware, 1-2 overview of serial software, 1-4 P parity, 3-3 PCI serial board installation (figure)
Index duplex architectures, A-3 termination, A-5 serial hardware forcing Windows to detect, C-4 general programming requirements, 4-1 installation, 2-3 overview, 1-2 selecting an interface to uninstall (figure), B-2 uninstalling, B-1 using, 4-1 using with LabVIEW and LabWindows/CVI, 1-5 serial port information, A-1 serial port names, 2-5 serial software add/remove programs properties dialog box (figure), B-3 installation, 2-1 overview, 1-4 successful uninstallation (figure), B-4 uninstalling, B-2 setting t
Index V straight-through cabling in a DTE-to-DCE interface (figure), A-7 successful uninstallation (figure), B-4 system integration, by National Instruments, E-1 verifying hardware installation, 2-5 viewing or changing communication port settings, 3-1 W T Web support from National Instruments, E-1 Win32 Overviews and Win32 Reference, 4-1 Win32 Software Development Kit, 4-1 worldwide technical support, E-2 technical support resources, E-1 termination, A-5 multidrop network using terminating resistors
