Farnell NI-9881 User manual

NI-9881 Getting
Started
2022-07-06

Contents
Before You Begin. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Safety Guidelines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Safety Guidelines for Hazardous Locations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Wiring the NI-9881. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
CAN Bus Topology and Termination. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Connecting a CAN Bus to the NI-9881. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Cabling Requirements for the NI 9881. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Cable Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Termination Resistors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Cable Lengths. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Number of CAN Nodes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
NI-9881 Hardware Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
NI-9881 Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
High-Speed CAN Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Power Requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Physical Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Safety Voltages. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Shock and Vibration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Environmental. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
NI Services. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
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NI-9881 Getting Started

Before You Begin
Read the NI-9881 Safety, Environmental, and Regulatory Information and
complete the soware and hardware installation procedures in your chassis
documentation.
Safety Guidelines
Caution Observe all instructions and cautions in the user documentation.
Using the product in a manner not specified can damage the product and
compromise the built-in safety protection.
Attention Suivez toutes les instructions et respectez toutes les mises
en garde de la documentation d'utilisation. L'utilisation du produit de
toute autre façon que celle spécifiée risque de l'endommager et de
compromettre la protection de sécurité intégrée.
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 Gc and Ex nA IIC T4 Gc 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 o or the area is known to be nonhazardous.
Caution Do not remove modules unless power has been switched o or
the area is known to be nonhazardous.
© National Instruments 3
NI-9881 Getting Started

Caution Substitution of components may impair suitability for Class I,
Division 2, or Zone 2.
Caution The system must be installed in an enclosure certified for the
intended hazardous (classified) location, having a tool secured cover/door,
where a minimum protection of at least IP54 is provided.
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 07ATEX 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.
Caution Transient protection shall be provided that is set at a level not
exceeding 140% of the peak rated voltage value of 85 V at the supply
terminals to the equipment.
Caution The system shall only be used in an area of not more than
Pollution Degree 2, as defined in IEC/EN 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.
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NI-9881 Getting Started

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 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 the table below.
The NI-9881 features soware-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. The Termination Resistor Specification
table lists recommended termination resistor values.
Figure 1. NI-9881 Pinout
Pin Signal
1 No Connection (NC)
2 CAN_L
3 COM
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NI-9881 Getting Started

Pin Signal
4 NC
5 SHLD
6 COM
7 CAN_H
8 NC
9 VSUP
Table 1. Pin Assignments for the NI-9881
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 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.
The following figure shows a simplified diagram of a CAN bus with multiple CAN
nodes and proper termination resistor (Rt) locations.
Figure 2. CAN Bus Topology and Termination Resistor Locations
Connecting a CAN Bus to the NI-9881
You can connect the NI-9881 port to any location on a CAN bus. The following figure
shows one example of connecting the NI-9881 directly to one CAN node.
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NI-9881 Getting Started

Figure 3. Connecting the NI-9881 to a CAN Device
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.
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
Table 2. ISO 11898 Specifications for Characteristics of a CAN_H and CAN_L Pair of Wires
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. The onboard,
soware-selectable termination has a nominal value of 120 Ω. If you are not using
the onboard termination, use the values listed in Table 3.
Characteristic Value Condition
Termination resistor, Rt100 Ω min, Minimum power dissipation: 220 mW
120 Ω nominal,
130 Ω max
Table 3. Termination Resistor Specification
© National Instruments 7
NI-9881 Getting Started

Cable Lengths
The cabling characteristics and desired bit transmission rates aect 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.
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.
Figure 4. NI-9881 Hardware Overview
NI-9881 Specifications
The following specifications are typical for the range -40 °C to 70 °C unless otherwise
noted.
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NI-9881 Getting Started

High-Speed CAN Characteristics
Transceiver NXP PCA82C251T
Max baud rate 1 Mbps
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 maximum
Sleep mode 2.55 mW maximum
Thermal dissipation (at 70 °C)
Active mode 1.25 W maximum
Sleep mode 250 mW maximum
Physical Characteristics
Dimensions Visit ni.com/dimensions and search by module number.
Weight Approximately 144 g (5.0 oz)
Safety Voltages
Connect only voltages that are within the following limits:
Maximum voltage[1]
Port-to-COM -27 V DC to +40 V DC maximum, Measurement Category I
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NI-9881 Getting Started

External power supply (Vsup) +9 V DC to +30 V DC
Isolation
Port-to-earth ground
Continuous 60 V DC, Measurement Category I
Withstand 500 V RMS, verified by a 5 s dielectric withstand test
1 The maximum voltage that can be applied or output between any port or Vsup
terminal and a COM terminal without creating a safety hazard.
Shock and Vibration
To meet these specifications, you must panel mount the system.
Operating vibration
Random 5 g RMS, 10 Hz to 500 Hz
Sinusoidal 5 g, 10 Hz to 500 Hz
Operating shock 30 g, 11 ms half sine; 50 g, 3 ms half sine; 18 shocks at 6 orientations
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 (with power plug attached) IP 40
Operating humidity (IEC 60068-2-78) 10% RH to 90% RH, noncondensing
Storage humidity (IEC 60068-2-78) 5% RH to 95% RH, noncondensing
Pollution Degree 2
Maximum altitude 5,000 m
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NI-9881 Getting Started