National Instruments 9871 Getting Started

GETTING STARTED GUIDE

NI 9871

4-Port, RS485/RS422 Serial Module

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ni.com/manuals

This document explains how to connect to the National
Instruments 9871.

Note Before you begin, complete the software and

hardware installation procedures in your chassis
documentation.

Note The guidelines in this document are specific to

the NI 9871. The other components in the system might
not meet the same safety ratings. Refer to the
documentation for each component in the system to
determine the safety and EMC ratings for the entire
system.

Safety Guidelines

Operate the NI 9871 only as described in this document.

Hot Surface This icon denotes that the component

may be hot. Touching this component may result in
bodily injury

.

Caution Do not operate the NI 9871 in a manner not

specified in this document. Product misuse can result in

2

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| NI 9871 Getting Started Guide

a hazard. You can compromise the safety protection
built into the product if the product is damaged in any
way. If the product is damaged, return it to National
Instruments for repair

.

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 IIC T4
and Ex nA IIC 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.

Caution Do not disconnect I/O-side wires or

connectors unless power has been switched off or the
area is known to be nonhazardous.

Caution Do not remove modules unless power has

been switched off or the area is known to be
nonhazardous.

Caution Substitution of components may impair

suitability for Class I, Division 2

.

NI 9871 Getting Started Guide | © National Instr

uments | 3

Caution For Division 2 and Zone 2 applications,

install the system in an enclosure rated to at least IP54
as defined by

IEC/EN 60079-15.

Caution For Zone 2 applications, install a protection

device between the RS232 signal cables and the
NI 9871 RJ-50 jacks (ports 1 to 4). The device must
prevent the RS232 signal-to-signal or signal-to-COM
voltage from exceeding 35 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 V

sup

and COM pins. The device must prevent

the V

sup

-to-COM voltage from exceeding 39 V

if there

is a transient overvoltage condition.

Special Conditions for Hazardous Locations Use in
Europe and Internationally

The

NI 9871 has been evaluated as Ex nA IIC T4 Gc equipment
under DEMKO Certificate No. 07 ATEX 0626664X and is
IECEx 14.0089X certified. Each NI 9871 is marked II 3G and
is suitable for use in Zone 2 hazardous locations, in ambient
temperatures of -40 °C ≤ T

a ≤ 70 °C. If you are using the NI 9871

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| NI 9871 Getting Started Guide

in Gas Group IIC hazardous locations, you must use the device in
an NI chassis that has been evaluated as Ex nC IIC T4, Ex IIC
T4, Ex nA IIC T4, or Ex nL IIC T4 equipment.

Caution You must make sure that transient

disturbances do not exceed 140% of the rated voltage.

Caution The system shall only be used in an area of

not more than Pollution Degree 2, as defined in
IEC 60664-1.

Caution The system shall be mounted in an

ATEX/IECEx-certified enclosure with a minimum
ingress protection rating of at least IP54 as defined in
IEC/EN 60079-15.

Caution The enclosure must have a door or cover

accessible only by the use of a tool.

Special Conditions for Marine Applications

Some products are Lloyd’s Register (LR) T

ype Approved for
marine (shipboard) applications. To verify Lloyd’s Register
certification for a product, visit ni.com/certification and search
for the LR certificate, or look for the Lloyd’s Register mark on
the product.

NI 9871 Getting Started Guide | © National Instr

uments | 5

Caution In order to meet the EMC requirements for

marine applications, install the product in a shielded
enclosure with shielded and/or filtered power and
input/output ports. In addition, take precautions when
designing, selecting, and installing measurement probes
and cables to ensure that the desired EMC performance
is attained.

Wiring the NI 9871

The NI 9871 has four RJ-50 receptacles that provide connections
for four RS485/RS422 devices.

6 | ni.com | NI 9871 Getting Started Guide

Table 1. RS485/RS422 Port Pinout

RJ-50 Pin Signal Name*

RJ50 Jack

NC
TXD–
TXD+
R

TS–
CTS–
RXD–
RXD+
R

TS+
CTS+
COM

1
2
3
4
5
6
7
8
9

10

1 No Connect

2 TXD-

3 TXD+

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 Getting Started Guide | © National Instruments | 7

The cables included with your kit convert the RJ-50 pinout to the
standard NI pinout on a DB-9 male connector, as shown in
T

able 2.

Table 2. Pin Assignments for RS485/RS422 DB-9 Male Connector

Connector RJ-50 Pin Signal Name

6
7
8
9

1
2
3
4
5

1 GND

2 CTS+

3 RTS+

4 RXD+

5 RXD-

6 CTS-

7 RTS-

8 TXD+

9 TXD-

8 | ni.com | NI 9871 Getting Started Guide

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.

Caution To ensure the specified EMC performance,

do not connect the power input to a DC mains supply
or to any supply requiring a connecting cable longer
than

30 m (100 ft). A DC mains supply is a local DC
electricity supply network in the infrastructure of a
certain site or building.

NI 9871 Getting Started Guide | © National Instr

uments | 9

Figure 1. Four-Position External Power Connector

1

3

4

2

1. V

SUP

2. V

SUP

3. COM

4. COM

Figure 2 shows the method of power connection to the NI 9871
module. Attach an isolated power supply to the V

SUP

and COM

terminals using the included pigtail.

10 | ni.com | NI 9871 Getting Started Guide

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

Red (+)

Black (–)

NI P/N 198159-XX:

Female Microfit

Pigtail

V+
V–

An

y 8 to 28 V

Isolated

Po

wer Supply

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. One Y

-adapter is needed for each
additional module. Ensure that the power supply can handle
maximum power requirements for all modules connected.

Caution Make all connections before applying power

.

NI 9871 Getting Star

ted Guide

| © National Instr

uments | 11

Figure 3. Powering Multiple Modules from a Single Power Supply

Red (+)

Black (–)

NI P/N 198303-XX:

Male Microfit

Y-Adapter

NI P/N 198159-XX:

Female Microfit

Pigtail

V+
V–

Any 8 to 28 V

Isolated

P

o

wer Supply

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.

12 | ni.com | NI 9871 Getting Started Guide

Figure 4. 4-Wire Full-Duplex Multidrop Network

Using Terminating Resistors

MASTER

Slave 1

120 Ω

Slave 2 Slave n

120 Ω

Tx

Tx

Rx

Tx

Rx

Tx

Rx

Rx

120 Ω

120 Ω

Figure 5. 2-Wire Multidrop Network Using Terminating Resistors

MASTER

Slave 1

120 Ω

Slave 2 Slave n

120 Ω

Tx

Tx

Rx

Tx

Rx

Tx

Rx

Rx

The driver directly supports 4-wire full-duplex operation on peer­to-peer RS-485 networks. Multidrop RS-485 networks require
additional software development.

RS485 terminators are available at ni.com/serial.

NI 9871 Getting Started Guide | © National Instruments | 13

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

Enable 4-Wire

2-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.

14 | ni.com | NI 9871 Getting Started Guide

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 °C to
70 °C unless otherwise noted.

Maximum baud rate 3.6864 Mbps

Maximum module
throughput

1.28 Mbps

Maximum cable length 1.2 km (4,000 ft)

NI 9871 Getting Started Guide | © National Instruments | 15

Data line ESD protection
(human body model)

±15 kV

MTBF 514,016 hours at 25 °C; Bellcore

Issue 6, Method 1, Case 3,
Limited Part Stress Method

Note Contact NI for Bellcore MTBF specifications at

other temperatures or 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 W max

Required external supply
voltage range (V

SUP

)

+8 to +28 VDC

16 | ni.com | NI 9871 Getting Started Guide

Power supply consumption from external supply V

SUP

Typical 1 W

Maximum 3.5 W

Physical Characteristics

To clean the module, wipe it with a dry towel.

Weight Approx. 153 g (5.4 oz)

Safety

Maximum Voltage

1

Connect only the voltages that are within these limits.

RS485/RS422 Port-to-COM -8 to +13 VDC max,

Measurement Category I

V

SUP

-to-COM ±28 V max, Measurement
Category I

1

The maximum voltage that can be applied or output without creating a safety
hazard.

NI 9871 Getting Started Guide | © National Instruments | 17

Measurement Category I is for measurement 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. This category is
for measurements of voltages from specially protected secondary
circuits. Such voltage measurements included signal levels,
special equipment, limited-energy parts of equipment, circuits
powered by regulated low-voltage sources, and electronics.

Caution Do not connect to signals or use for

measurements within Measurement Categories II, III,
or IV.

Isolation V

oltages

Port-to-earth ground

Continuous 60 VDC, Measurement

Category I up to 5,000 m in
altitude

18 | ni.com | NI 9871 Getting Started Guide

Withstand

up to 2,000 m in
altitude

1000 V

rms

verified by a 5s

dielectric withstand test

up to 5,000 m in
altitude

500 V

rms

verified by a 5s

dielectric withstand test

Safety and Hazardous Locations Standards

This product is designed to meet the requirements of the
following electrical equipment safety standards for measurement,
control, and laboratory use:

• IEC 61010-1, EN 61010-1

• UL 61010-1, CSA 61010-1

• EN 60079-0:2012, EN 60079-15:2010

• IEC 60079-0: Ed 6, IEC 60079-15; Ed 4

• UL 60079-0; Ed 5, UL 60079-15; Ed 3

• CSA 60079-0:2011, CSA 60079-15:2012

Note For UL and other safety certifications, refer to

the product label or the Online Product Certification
section.

NI 9871 Getting Star

ted Guide | © National Instr

uments | 19

Hazardous Locations

U.S. (UL) Class I, Division 2, Groups A,

B, C, D, T4; Class I, Zone 2,
AEx nA IIC T4

Canada (C-UL) Class I, Division 2, Groups A,

B, C, D, T4; Class I, Zone 2, Ex
nA IIC T4

Europe (DEMKO) Ex nA IIC T4 Gc

Environmental

Refer to the manual for the chassis you are using for more
information about meeting these specifications.

Operating temperature
(IEC 60068-2-1, IEC 60068-2-2)

-40 °C to 70 °C

Storage temperature
(IEC 60068-2-1, IEC 60068-2-2)

-40 °C to 85 °C

Ingress protection IP 30

20 | ni.com | NI 9871 Getting Started Guide

Operating humidity
(IEC 60068-2-56)

10% RH to 90% RH,
noncondensing

Storage humidity
(IEC 60068-2-56)

5% RH to 95% RH,
noncondensing

Pollution degree 2

Maximum altitude 5,000 m

Indoor use only.

Shock and Vibr

ation

To meet these specifications, you must panel mount the system.

Operating vibration

Random (IEC
60068-2-64)

5 g

rms

, 10 Hz to 500 Hz

Sinusoidal (IEC
60068-2-6)

5 g, 10 Hz 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

NI 9871 Getting Started Guide | © National Instruments | 21

Electromagnetic Compatibility

This product meets the requirements of the following EMC
standards for electrical equipment for measurement, control, and
laboratory use:

• EN 61326 (IEC 61326): Class A emissions; Basic immunity

• EN 55011 (CISPR 11): Group 1, Class A emissions

• AS/NZS CISPR 11: Group 1, Class A emissions

• FCC 47 CFR Part 15B: Class A emissions

• ICES-001: Class A 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 product

according to the documentation.

22 | ni.com | NI 9871 Getting Started Guide

CE Compliance

This product meets the essential requirements of applicable
European Directives, as follows:

• 2014/35/EU; Low-V

oltage Directive (safety)

• 2014/30/EU; Electromagnetic Compatibility Directive
(EMC)

• 94/9/EC; Potentially Explosive Atmospheres (ATEX)

Online Product Certification

Refer to the product Declaration of Conformity (DoC) for
additional regulatory compliance information. To obtain product
certifications and the DoC for this product, visit ni.com/

certification, search by model number or product line, and click

the appropriate link in the Certification column.

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.

NI 9871 Getting Started Guide | © National Instr

uments | 23

For additional environmental information, refer to the Minimize
Our Environmental Impact web page at

ni.com/environment. This

page contains the environmental regulations and directives with
which NI complies, as well as other environmental information
not included in this document.

Waste Electrical and Electronic Equipment (WEEE)

EU Customers At the end of the product life cycle, all

NI products must be disposed of according to local
laws and regulations. For more information about how
to recycle NI products in your region, visit ni.com/

environment/weee.

电子信息产品污染控制管理办法（中国 RoHS

）

中国客户 National Instruments 符合中国电子信息产

品中限制使用某些有害物质指令(RoHS)。关于
National Instruments 中国 RoHS 合规性信息，请登
录 ni.com/environment/rohs_china。(For

information about China RoHS compliance, go to

ni.com/environment/rohs_china.)

24

| ni.com | NI 9871 Getting Started Guide

Worldwide Support and Services

The National Instruments website is your complete resource for
technical support. At ni.com/support, you have access to
everything from troubleshooting and application development
self-help resources to email and phone assistance from NI
Application Engineers.

Visit ni.com/services

for NI Factory Installation Services, repairs,

extended warranty, and other services.

Visit ni.com/register to register your National Instruments
product. Product registration facilitates technical support and
ensures that you receive important information updates from NI.

A Declaration of Conformity (DoC) is our claim of compliance
with the Council of the European Communities using the
manufacturer’s declaration of conformity. This system affords the
user protection for electromagnetic compatibility (EMC) and
product safety. You can obtain the DoC for your product by
visiting ni.com/certification. If your product supports calibration,
you can obtain the calibration certificate for your product at

ni.com/calibration.

NI 9871 Getting Started Guide | © National Instr

uments | 25

National Instruments corporate headquarters is located at
11500 North Mopac Expressway, Austin, T

exas, 78759-3504.
National Instruments also has offices located around the world.
For telephone support in the United States, create your service
request at ni.com/support or dial 1 866 ASK MYNI (275 6964).
For telephone support outside the United States, visit the
Worldwide Offices section of ni.com/niglobal to access the branch
office websites, which provide up-to-date contact information,
support phone numbers, email addresses, and current events.

Refer to the NI Tr

ademarks and Logo Guidelines at ni.com/trademarks for information on NI

trademarks. Other product and company names mentioned herein are trademarks or trade names
of their respective companies. For patents covering NI products/technology, refer to the
appropriate location: Help»Patents in your software, the patents.txt file on your media, or the
National Instruments Patent Notice at ni.com/patents. You can find information about end-user
license agreements (EULAs) and third-party legal notices in the readme file for your NI product.
Refer to the Export Compliance Information at ni.com/legal/export-compliance for the NI
global trade compliance policy and how to obtain relevant HTS codes, ECCNs, and other import/
export data. NI MAKES NO EXPRESS OR IMPLIED WARRANTIES AS TO THE ACCURACY OF
THE INFORMATION CONTAINED HEREIN AND SHALL NOT BE LIABLE FOR ANY ERRORS.
U.S. Government Customers: The data contained in this manual was developed at private
expense and is subject to the applicable limited rights and restricted data rights as set forth in FAR

52.227-14, DFAR 252.227-7014, and DFAR 252.227-7015.

© 2007—2017 National Instruments. All rights reserved.

372277G-01 December 1, 2017