National Instruments NI 9881 User manual

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GETTING STARTED GUIDE
NI 9881
1-Port CANopen Module
This document explains how to connect to the NI 9881.
The NI 9881 module requires the latest NI-CANopen software to
be installed. The latest version of the NI-CANopen software is at
ni.com/downloads.
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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 9881. 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 9881 only as described in this document.
Caution Do not operate the NI 9881 in a manner not
specified in this document. 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 NI for
repair.
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Safety Guidelines for Hazardous Locations
The NI 9881 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 9881 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 Division 2 and Zone 2 applications,
install the system in an enclosure rated to at least IP54
as defined by IEC/EN 60079-15.
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Caution For Division 2 and Zone 2 applications,
install a protection device between the external power
supply and the Vsup pin. The device must prevent the
Vsup-to-COM voltage from exceeding 50 V if there is
a transient overvoltage condition.
Caution For Zone 2 applications, install a protection
device between the CAN signals and the NI 9881 CAN
pins. The device must prevent the CAN Port-to-COM
voltage from exceeding 55 V if there is a transient
overvoltage condition.
Special Conditions for Hazardous Locations Use in
Europe and Internationally
The NI 9881 has been evaluated as Ex nA IIC T4 Gc equipment
under DEMKO Certificate No. 07 ATEX 0626664X and is
IECEx UL 14.0089X certified. Each NI 9881 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 9881
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.
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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.
Wiring the NI 9881
The NI 9881 has one 9-pin male D-Sub connector that provides
connections to a CAN bus. The NI 9881 has pins for CAN_H and
CAN_L, to which you connect the CAN bus signals. Connect
these signals using twisted-pair cable.
The port has two common pins (COM) that are internally
connected to the module’s isolated reference and serve as the
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reference ground for CAN_H and CAN_L. You can connect the
CAN bus reference ground (sometimes referred to as CAN_V-) to
one or both COM pins. The port also has an optional shield pin,
SHLD, that you can connect to a shielded CAN cable.
Connecting SHLD may improve signal integrity and EMC
performance in a noisy environment.
Caution You must use a UL listed ITE power supply
marked LPS with the NI 9881.
The NI 9881 requires an external power supply of +9 to +30 V to
operate. Supply power to the NI 9881 VSUP pin.
Note Power on VSUP is required for CANopen
operation.
The NI 9881 pinout is listed in Table 1.
The NI 9881 features software-selectable bus termination for
High-Speed CAN transceivers. On the NI 9881, you can enable
120 Ω termination resistors between CAN_H and CAN_L
through an API call. Table 3 lists recommended termination
resistor values.
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Table 1. Pin Assignments for the NI 9881
Connector Pin Signal
6
7
8
9
1
2
3
4
5
1 No Connection (NC)
2 CAN_L
3 COM
4 NC
5 SHLD
6 COM
7 CAN_H
8 NC
9 VSUP
CAN Bus Topology and Termination
A CAN bus consists of two or more CAN nodes cabled together.
The CAN_H and CAN_L pins of each node are connected to the
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main CAN bus cable through a short connection known as a
“stub.” The pair of signal wires, CAN_H and CAN_L, constitutes
a transmission line. If the transmission line is not terminated,
each signal change on the bus causes reflections that may cause
communication errors. Because the CAN bus is bidirectional,
both ends of the cable must be terminated. However, this
requirement does not mean that every node on the bus should
have a termination resistor; only the two nodes at the far end of
the cable should have termination resistors.
Figure 1 shows a simplified diagram of a CAN bus with multiple
CAN nodes and proper termination resistor (Rt) locations.
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Figure 1. CAN Bus Topology and Termination Resistor Locations
CAN
Node
CAN
Node
CAN
Node
RtRt
CAN
Node
CAN_H
CAN_L
CAN_H
CAN_L
CAN_H CAN_L CAN_H CAN_L
Bus Cable Length
Stub
Length
Connecting a CAN Bus to the NI 9881
You can connect the NI 9881 port to any location on a CAN bus.
Figure 2 shows one example of connecting the NI 9881 directly
to one CAN node.
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Figure 2. Connecting the NI 9881 to a CAN Device
C Series
Module
CAN Device
Rt
CAN
Cable
(With
Optional
Shield)
(SHLD)
CAN_H
CAN_L
Vsup
COM
Rt
(SHLD)
CAN_H
CAN_L
Vsup
COM
Cabling Requirements for the NI 9881
Cable Specifications
Cables should meet the physical medium requirements specified
in ISO 11898, shown in the following table. Belden cable
(3084A) meets all these requirements and should be suitable for
most applications.
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Table 2. ISO 11898 Specifications for Characteristics of a CAN_H and
CAN_L Pair of Wires
Characteristic Value
Impedance 95 Ω min,
120 Ω nominal,
140 Ω max
Length-related resistance 70 mΩ/m nominal
Specific line delay 5 ns/m nominal
Termination Resistors
The termination resistors (Rt) should match the nominal
impedance of the CAN cable and therefore comply with the
values in the following table.
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Table 3. Termination Resistor Specification
Characteristic Value Condition
Termination resistor, Rt100 Ω min, Minimum power dissipation:
220 mW
120 Ω nominal,
130 Ω max
Cable Lengths
The cabling characteristics and desired bit transmission rates
affect the allowable cable length. You can find detailed cable
length recommendations in the ISO 11898, CiA DS 102, and
DeviceNet specifications.
ISO 11898 specifies 40 m total cable length with a maximum
stub length of 0.3 m for a bit rate of 1 Mb/s. The ISO 11898
specification says that significantly longer cable lengths may be
allowed at lower bit rates, but you should analyze each node for
signal integrity problems.
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Number of CAN Nodes
The maximum number of nodes depends on the electrical
characteristics of the nodes on the network. If all nodes meet the
ISO 11898 requirements, you can connect at least 30 nodes to the
bus. You can connect higher numbers of nodes if the nodes’
electrical characteristics do not degrade signal quality below
ISO 11898 signal level specifications.
The NI 9881 electrical characteristics allow at least 110 CAN
ports on a network.
NI 9881 Hardware Overview
The NI 9881 has one full-featured CAN port that is isolated from
the other modules in the system. The port has a Bosch DCAN
CAN controller that is CAN 2.0B-compatible and fully supports
both 11-bit and 29-bit identifiers. The port also has an
NXP PCA82C251T High-Speed CAN transceiver that is fully
compatible with the ISO 11898 standard and supports baud rates
up to 1 Mbps.
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Figure 3. NI 9881 Hardware Overview
Ext Pwr
Supply
Required
Rx
Tx
CAN
Controller
CAN_H
CAN_L
CAN
Transceiver
Rx
Tx
COM
Vsup
+
_
NI 9881 Specifications
The following specifications are typical for the range -40 °C to
70 °C unless otherwise noted.
High-Speed CAN Characteristics
Transceiver NXP PCA82C251T
Max baud rate 1 Mbps
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CAN_H, CAN_L bus lines
voltage
-27 to +40 VDC
CAN Supply voltage range
(VSUP)
+9 to +30 VDC
MTBF Contact NI for Bellcore MTBF
or MIL-HDBK-217F
specifications.
Power Requirements
Power consumption from chassis
Active mode 1 W max
Sleep mode 2.55 mW max
Thermal dissipation (at 70 °C)
Active mode 1.25 W max
Sleep mode 250 mW max
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Physical Characteristics
To clean the module, wipe it with a dry towel.
Weight Approx. 144 g (5.0 oz)
Safety
Connect only voltages that are within the following limits:
Maximum Voltage1
Port-to-COM -27 to +40 VDC max,
Measurement Category I
Isolation
Port-to-earth ground
Continuous 60 VDC,
Measurement Category I
Withstand 500 Vrms, verified by a 5 s
dielectric withstand test
1The maximum voltage that can be applied or output between any port or VSUP
terminal and a COM terminal without creating a safety hazard.
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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 the NI 9881 to signals or use
for measurements within Measurement Categories II,
III, or IV.
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
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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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Electromagnetic Compatibility
This product meets the requirements of the following EMC
standards for sensitive electrical equipment for measurement,
control, and laboratory use:
• EN 61326 (IEC 61326): Class A emissions; Industrial
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 In the United States (per FCC 47 CFR), Class A
equipment is intended for use in commercial, light-
industrial, and heavy-industrial locations. In Europe,
Canada, Australia and New Zealand (per CISPR 11)
Class A equipment is intended for use only in heavy-
industrial locations.
Note Group 1 equipment (per CISPR 11) is any
industrial, scientific, or medical equipment that does
not intentionally generate radio frequency energy for
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