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 your system may not meet the same safety
ratings and specifications. Refer to the documentation for
each component in your system to determine the safety
ratings and specifications for the entire system.

© National Instruments 3 NI 9871 Operating Instructions
Safety Guidelines
Caution Do not operate the NI 9871 in a manner not
specified in the user manual or operating instructions.
Product misuse can result in 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.
Hot Surface This icon denotes that the component may be
hot. Touching this component may result in bodily injury.
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.

NI 9871 Operating Instructions 4 ni.com
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.
Caution For Zone 2 applications, install a protection
device between the RS232 signal cables and the NI 9871
RJ-50 jacks (ports 1–4). 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 Vsup and COM pins. The device must prevent the
Vsup-to-COM voltage from exceeding 39 V if there is a
transient overvoltage condition.

© National Instruments 5 NI 9871 Operating Instructions
Special Conditions for Safe Use 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.
Special Guidelines for Marine Applications
Some modules are Lloyd’s Register (LR) Type Approved for
marine (shipboard) applications. To verify Lloyd’s Register
certification for a module, visit ni.com/certification and
search for the LR certificate, or look for the Lloyd’s Register mark
on the product label.
Caution In order to meet the EMC requirements for
marine applications, install the module 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.

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 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.
Caution To ensure the specified EMC performance, do not
connect the power input to a d.c. mains supply or to any
supply requiring a connecting cable longer than 30 m
(100 ft.). A d.c. mains supply is a local d.c. electricity supply
network in the infrastructure of a certain site or building.

© National Instruments 9 NI 9871 Operating Instructions
Figure 1. Four-Position External Power Connector
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.
1V
SUP 2V SUP 3COM 4COM
1
3
4
2

NI 9871 Operating Instructions 10 ni.com
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
additional module. Ensure that the power supply can handle
maximum power requirements for all modules connected.
Red (+)
Black (–)
NI P/N 198159-XX:
Female Microfit
Pigtail
V+
V–
Any 8 - 28 V
Isolated
Power Supply

© National Instruments 11 NI 9871 Operating Instructions
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

NI 9871 Operating Instructions 12 ni.com
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

© National Instruments 13 NI 9871 Operating Instructions
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#

NI 9871 Operating Instructions 14 ni.com
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 module throughput ..........1.28 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

© National Instruments 15 NI 9871 Operating Instructions
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)

NI 9871 Operating Instructions 16 ni.com
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.

© National Instruments 17 NI 9871 Operating Instructions
Isolation Voltages
Port-to-earth ground
Continuous ................................. 60 VDC,
Measurement Category I up
to 5,000 m altitude
Withstand
up to 2,000 m altitude .......... 1000 Vrms, verified by a 5 s
dielectric withstand test
up to 5,000 m altitude .......... 500 Vrms, verified by a 5 s
dielectric withstand test
Safety Standards
This product meets 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 the Online Product Certification section.

NI 9871 Operating Instructions 18 ni.com
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
Environmental
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 30
Operating humidity........................... 10 to 90% RH,
noncondensing
Storage humidity............................... 5 to 95% RH,
noncondensing

© National Instruments 19 NI 9871 Operating Instructions
Pollution Degree (IEC 60664) .......... 2
Maximum altitude............................. 5,000 m
Indoor use only
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

NI 9871 Operating Instructions 20 ni.com
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.