OPERATING INSTRUCTIONS AND SPECIFICATIONS NI 9871 4-Port, RS485/RS422 Serial Module
This document describes how to use the National Instruments 9871 and includes specifications and pin assignments for the NI 9871. Visit ni.com/info and enter rdsoftwareversion to determine which software you need for the modules you are using. For information about installing, configuring, and programming the system, refer to the system documentation. Visit ni.com/info and enter cseriesdoc for information about C Series documentation.
Safety Guidelines for Hazardous Locations The NI 9871 is suitable for use in Class I, Division 2, Groups A, B, C, D, T4 hazardous locations; Class I, Zone 2, AEx nA II T4 and Ex nA II T4 hazardous locations; and nonhazardous locations only. Follow these guidelines if you are installing the NI 9871 in a potentially explosive environment. Not following these guidelines may result in serious injury or death.
For Zone 2 applications, install a protection device between the RS485/RS422 signal cables and the NI 9871 RJ-50 jacks (ports 1–4). The device must prevent the RS485/RS422 signal-to-signal or signal-to-COM voltage from exceeding 23 V if there is a transient overvoltage condition. Caution For Zone 2 applications, install a protection device between the external power supply and the NI 9871 Vsup and COM pins.
Special Conditions for Marine Applications Some modules are Lloyd’s Register (LR) Type Approved for marine applications. To verify Lloyd’s Register certification, visit ni.com/certification and search for the LR certificate, or look for the Lloyd’s Register mark on the module. To meet radio frequency emission requirements for marine applications, use shielded cables and install the system in a metal enclosure.
Wiring the NI 9871 The NI 9871 has four RJ-50 receptacles that provide connections for four RS485/RS422 devices. Table 1. RS485/RS422 Port Pinout RJ-50 Pin Signal Name* 1 No Connect 2 TXD– 3 TXD+ RJ50 Jack 1 2 3 4 5 6 7 8 9 10 NC TXD– TXD+ RTS– CTS– RXD– RXD+ RTS+ CTS+ COM 4 RTS– 5 CTS– 6 RXD– 7 RXD+ 8 RTS+ 9 CTS+ 10 GND * These signals are shared by all four RJ-50 connectors on the NI 9871. NI 9871 Operating Instructions 6 ni.
The cables included with your kit convert the RJ-50 pinout to the standard NI pinout, as shown in Table 2. Table 2. Pin Assignments for RS485/RS422 DB-9 Male Connector Connector 6 7 8 9 1 2 3 4 5 © National Instruments Corp.
You must connect an external power supply to the NI 9871. This power supply provides the power for the RS485/RS422 transceivers on the module. You can use the included female four-position pigtail to connect to an external voltage source. Figure 1 lists the connections between an external voltage source (of +8 V to +28 V) and the NI 9871. 2 4 1 3 1 VSUP 2 VSUP 3 COM 4 COM Figure 1. Four-Position External Power Connector NI 9871 Operating Instructions 8 ni.
Figure 2 shows the method of power connection to the NI 9871 module. Attach an isolated power supply to the Vsup and COM terminals using the included pigtail. V+ V– Any 8 - 28 V Isolated Power Supply Red (+) Black (–) NI P/N 198159-XX: Female Microfit Pigtail Figure 2. Powering the NI 9871 from an Isolated Power Source Figure 3 shows how to use the optional y-adapter (available at ni.com/serial) to connect power to more than one module using the same power source.
additional module. Ensure that the power supply can handle maximum power requirements for all modules connected. Caution All connections must be made before power is applied. NI P/N 198159-XX: Female Microfit Pigtail V+ V– Any 8 - 28 V Isolated Power Supply Red (+) Black (–) NI P/N 198303-XX: Male Microfit Y-Adapter Figure 3. Powering Multiple Modules from a Single Power Supply NI 9871 Operating Instructions 10 ni.
RS485 Bus Topology and Termination Refer to Figure 4 and Figure 5 for an overview of 4-wire and 2-wire RS485 bus topologies and termination. Slave 1 MASTER Tx Tx Rx Slave 2 Tx Rx Slave n Tx Rx 120 Ω 120 Ω 120 Ω 120 Ω Rx Figure 4. 4-Wire Full-Duplex Multidrop Network Using Terminating Resistors Slave 1 MASTER Tx Slave 2 Tx Rx Slave n Tx Rx Rx Tx 120 Ω 120 Ω Rx Figure 5. 2-Wire Multidrop Network Using Terminating Resistors RS485 terminators are available at ni.com/serial.
RS485 Transceiver Control Refer to Table 3 for a listing of TX and RX enable conditions for the different RS485 transceiver control modes. Table 3. Transceiver Control Pin Conditions 2-Wire Enable 4-Wire DTR/Echo DTR/No Echo Auto TX On DTR DTR TX RX On On DTR# TX# NI 9871 Hardware Overview The NI 9871 has four independent RS485/RS422 ports that are isolated from the other modules in the system. Each port is fully compatible with the ANSI/EIA/TIA-485 standard.
Sleep Mode (CompactRIO Only) You can enable sleep mode for the CompactRIO system in software. In sleep mode, the system consumes less power and may dissipate less heat. Typically, when a system is in sleep mode, you cannot communicate with the modules. Refer to the Specifications section for more information about power consumption and thermal dissipation. Specifications The following specifications are typical for the range –40 to 70 °C unless otherwise noted. Maximum baud rate..........................
Note Contact NI for Bellcore MTBF specifications at other temperatures or for MIL-HDBK-217F specifications. Power Requirements Power consumption from chassis Active mode ............................... 0.5 W max Sleep mode ................................. 50 μW max Thermal dissipation (at 70 °C) Active mode ............................... 1.5 W max Sleep mode ................................. 55 mW max Required external supply voltage range (VSUP) .........................
Safety Maximum Voltage1 Connect only voltages that are within these limits. RS485/RS422 Port-to-COM............. –8 to +13 VDC max, Measurement Category I VSUP-to-COM ................................... ±28 V max, Measurement Category I Measurement Category I is for measurements performed on circuits not directly connected to the electrical distribution system referred to as MAINS voltage. MAINS is a hazardous live electrical supply system that powers equipment.
Isolation Voltages Port-to-earth ground Withstand.................................... 1000 Vrms, verified by a dielectric withstand test, 5 s Continuous ................................. 60 VDC, Measurement Category I Hazardous Locations U.S. (UL) .......................................... Class I, Division 2, Groups A, B, C, D, T4; Class I, Zone 2, AEx nA II T4 Canada (C-UL) ................................. Class I, Division 2, Groups A, B, C, D, T4; Class I, Zone 2, Ex nA II T4 Europe (DEMKO)...........
Safety Standards The NI 9871 is designed to meet the requirements of the following standards of safety for electrical equipment for measurement, control, and laboratory use: • IEC 61010-1, EN 61010-1 • UL 61010-1, CSA 61010-1 Note For UL and other safety certifications, refer to the product label, or visit ni.com/certification, search by model number or product line, and click the appropriate link in the Certification column. Electromagnetic Compatibility Emissions.......................................
Note For the standards applied to assess the EMC of this product, refer to the Online Product Certification section. Note For EMC compliance, operate this device with shielded cabling. CE Compliance This product meets the essential requirements of applicable European Directives, as amended for CE marking, as follows: Low-Voltage Directive (safety)......... 2006/95/EC Electromagnetic Compatibility Directive (EMC) ...............................
Shock and Vibration To meet these specifications, you must panel mount the CompactRIO system. Operating vibration, random (IEC 60068-2-64) ................ 5 grms, 10 to 500 Hz Operating shock (IEC 60068-2-27).............................. 30 g, 11 ms half sine, 50 g, 3 ms half sine, 18 shocks at 6 orientations Operating vibration, sinusoidal (IEC 60068-2-6) .............. 5 g, 10 to 500 Hz Environmental CompactRIO modules are intended for indoor use only.
Operating humidity........................... 10 to 90% RH, noncondensing Storage humidity............................... 5 to 95% RH, noncondensing Maximum altitude............................. 2,000 m Pollution Degree (IEC 60664) .......... 2 Environmental Management NI is committed to designing and manufacturing products in an environmentally responsible manner. NI recognizes that eliminating certain hazardous substances from our products is beneficial to the environment and to NI customers.
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