National Instruments NI 9871 User manual

NI-9871

GETTING STARTED GUIDE
NI 9871
4-Port, RS485/RS422 Serial Module
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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
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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 Instruments | 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 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 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 ≤ Ta ≤ 70 °C. If you are using the NI 9871
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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) Type 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 Instruments | 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.
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Table 1. RS485/RS422 Port Pinout
RJ-50 Pin Signal Name*
RJ50 Jack
NC
TXD–
TXD+
RTS–
CTS–
RXD–
RXD+
RTS+
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
Table 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-
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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 Instruments | 9

Figure 1. Four-Position External Power Connector
1
3
4
2
1. VSUP
2. VSUP
3. COM
4. COM
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.
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Figure 2. Powering the NI 9871 from an Isolated Power Source
Red (+)
Black (–)
NI P/N 198159-XX:
Female Microfit
Pigtail
V+
V–
Any 8 to 28 V
Isolated
Power 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 Started Guide | © National Instruments | 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
Power 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.
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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 Ω120 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 peer-
to-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.
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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 (VSUP)
+8 to +28 VDC
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Power supply consumption from external supply VSUP
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 Voltage1
Connect only the 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
1The 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 Voltages
Port-to-earth ground
Continuous 60 VDC, Measurement
Category I up to 5,000 m in
altitude
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Withstand
up to 2,000 m in
altitude
1000 Vrms verified by a 5s
dielectric withstand test
up to 5,000 m in
altitude
500 Vrms 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.
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