National Instruments NI 9871, RS422, RS485

Figure2 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.

Figure 2. Powering the NI 9871 from an Isolated Power Source

Figure3 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. One y-adapter is needed for each

Red (+)

Black (–)

NI P/N 198159-XX:

Female Microfit

Pigtail

V+

V–

Any 8 - 28 V

Isolated

Power Supply

Contents

Main Safety Guidelines Safety Guidelines for Hazardous Locations Special Conditions for Hazardous Locations in Europe Special Conditions for Marine Applications 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* Table 2. Pin Assignments for RS485/RS422 DB-9 Male Connector Connector Pin Signal Page Page Page RS485 Bus Topology and Termination RS485 terminators are available at ni.com/serial. Figure 4. 4-Wire Full-Duplex Multidrop Network Using Terminating Resistors Figure 5. 2-Wire Multidrop Network Using Terminating Resistors RS485 Transceiver Control NI 9871 Hardware Overview Sleep Mode (CompactRIO Only) Specifications Power Requirements Physical Characteristics Safety Maximum Voltage Isolation Voltages Hazardous Locations Safety Standards Electromagnetic Compatibility CE Compliance Online Product Certification Shock and Vibration Environmental Environmental Management Waste Electrical and Electronic Equipment (WEEE) RoHS Where to Go for Support Page 372277B-01 Sep08