National Instruments NI 9871 User manual

OPERATING INSTRUCTIONS AND SPECIFICATIONS
NI 9871
4-Port, RS485/RS422 Serial Module

NI 9871 Operating Instructions 2 ni.com
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.
Note The safety guidelines and specifications in this
document are specific to the NI 9871. The other
components in the system might not meet the same safety
ratings and specifications. Refer to the documentation for
each component in the system to determine the safety
ratings and specifications for the entire system. Visit
ni.com/info and enter cseriesdoc for information
about C Series documentation.
Safety Guidelines
Operate the NI 9871 only as described in these operating
instructions.
Hot Surface This icon denotes that the component may be
hot. Touching this component may result in bodily injury.

© National Instruments Corp. 3 NI 9871 Operating Instructions
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.
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.
Caution For Zone 2 applications, install the
CompactRIO system in an enclosure rated to at least
IP 54 as defined by IEC 60529 and EN 60529.

NI 9871 Operating Instructions 4 ni.com
Caution 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. The device must prevent the
Vsup-to-COM voltage from exceeding 39 V if there is a
transient overvoltage condition.
Special Conditions for Hazardous Locations in Europe
This equipment has been evaluated as Ex nA IIC T4 equipment
under DEMKO Certificate No. 07 ATEX 0626664X. Each module
is marked II 3G and is suitable for use in Zone 2 hazardous
locations. If you are using the NI 9871 in Gas Group IIC hazardous
locations or in ambient temperatures of –40 °C ≤Ta ≤70 °C, you
must use the device in an NI chassis or controller that has been
evaluated as EEx nC IIC T4, Ex nA IIC T4, or Ex nL IIC T4
equipment.

© National Instruments Corp. 5 NI 9871 Operating Instructions
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.
Caution To meet radio frequency emission requirements
for marine applications, use shielded cables and install
the system in a metal enclosure. Suppression ferrites
must be installed on power supply inputs near power
entries to modules and controllers. Power supply and
module cables must be separated on opposite sides of the
enclosure and must enter and exit through opposing
enclosure walls.

NI 9871 Operating Instructions 6 ni.com
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*
1No Connect
2TXD–
3TXD+
4RTS–
5CTS–
6RXD–
7RXD+
8RTS+
9CTS+
10 GND
* These signals are shared by all four RJ-50 connectors on the NI 9871.
RJ50 Jack
NC
TXD–
TXD+
RTS–
CTS–
RXD–
RXD+
RTS+
CTS+
COM
1
2
3
4
5
6
7
8
9
10

© National Instruments Corp. 7 NI 9871 Operating Instructions
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 Pin Signal
1GND
2CTS+
3RTS+
4RXD+
5RXD–
6CTS–
7RTS–
8TXD+
9TXD–
6
7
8
9
1
2
3
4
5

NI 9871 Operating Instructions 8 ni.com
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.
Figure 1. Four-Position External Power Connector
1V
SUP 2V SUP 3COM 4COM
1
3
4
2

© National Instruments Corp. 9 NI 9871 Operating Instructions
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.
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. 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

NI 9871 Operating Instructions 10 ni.com
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.
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 - 28 V
Isolated
Power Supply

© National Instruments Corp. 11 NI 9871 Operating Instructions
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.
Figure 4. 4-Wire Full-Duplex Multidrop Network Using Terminating Resistors
Figure 5. 2-Wire Multidrop Network Using Terminating Resistors
RS485 terminators are available at ni.com/serial.
MASTER
Slave 1
120 Ω
Slave 2 Slave n
120 Ω
Tx
Tx Rx Tx Rx Tx Rx
Rx 120 Ω120 Ω
MASTER
Slave 1
120 Ω
Slave 2 Slave n
120 Ω
Tx
Tx Rx Tx Rx Tx Rx
Rx

NI 9871 Operating Instructions 12 ni.com
RS485 Transceiver Control
Refer to Table 3 for a listing of TX and RX enable conditions for
the different RS485 transceiver control modes.
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.
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#

© National Instruments Corp. 13 NI 9871 Operating Instructions
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.......................... 3.6864 Mbps
Maximum cable length ..................... 1.2 km (4,000 ft.)
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

NI 9871 Operating Instructions 14 ni.com
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) ......................... +8 to +28 VDC
Power supply consumption from external supply VSUP
Typical ........................................ 1 W
Maximum ................................... 3.5 W
Physical Characteristics
If you need to clean the module, wipe it with a dry towel.
Weight............................................... Approx. 153 g (5.4 oz)

© National Instruments Corp. 15 NI 9871 Operating Instructions
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. This category is for
measurements of voltages from specially protected secondary
circuits. Such voltage measurements include 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.
1 The maximum voltage that can be applied or output without creating a safety hazard.

NI 9871 Operating Instructions 16 ni.com
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)............................. Ex nA IIC T4

© National Instruments Corp. 17 NI 9871 Operating Instructions
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.......................................... EN 55011 Class A at 10 m
FCC Part 15A above 1 GHz
Immunity........................................... Industrial levels per
EN 61326-1:1997 +
A2:2001, Table A.1
EMC/EMI ......................................... CE, C-Tick, and FCC Part 15
(Class A) Compliant

NI 9871 Operating Instructions 18 ni.com
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) ............................... 2004/108/EC
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 module number or product line, and
click the appropriate link in the Certification column.

© National Instruments Corp. 19 NI 9871 Operating Instructions
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. For
outdoor use, mount the CompactRIO system in a suitably rated
enclosure. Refer to the installation instructions for the chassis you
are using for more information about meeting these specifications.
Operating temperature ...................... –40 to 70 °C
Storage temperature .......................... –40 to 85 °C
Ingress protection.............................. IP 40

NI 9871 Operating Instructions 20 ni.com
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.
For additional environmental information, refer to the NI and the
Environment 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.