National Instruments NI 9853 User manual

GETTING STARTED GUIDE
NI 9853
2-Port, High-Speed CAN Module
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This document explains how to connect to the NI 9853.

The NI 9853 module requires the latest NI 985x software to be
installed. The latest version of the NI 985x software is at ni.com/
downloads.
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 9853. 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 9853 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.
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Caution Do not operate the NI 9853 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.
Safety Guidelines for Hazardous Locations
The NI 9853 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 9853 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.
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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.
Caution For Zone 2 applications, install a protection
device between the CAN signals and the NI 9853 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 9853 has been evaluated as Ex nA IIC T4 Gc equipment
under DEMKO Certificate No. 03 ATEX 0324020X and is
IECEx 14.0089X certified. Each NI 9853 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 9853 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 9853
The NI 9853 has two 9-pin male D-Sub connectors that provide
connections to a CAN bus. Each port on the NI 9853 has pins for
CAN_H and CAN_L, to which you connect the CAN bus signals.
Connect these signals using twisted-pair cable.
Each 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.
CAN0 of the NI 9853 is internally powered, and therefore
requires no external power supply. CAN1 requires an external
power supply of +8 to +25 V to operate. Supply power to the
VSUP pin of CAN1 from the CAN bus.
Note Although CAN0 of the NI 9853 does not require
an external power supply to operate, it can be
connected to a powered CAN bus without being
damaged.
Pinouts for CAN0 and CAN1 of the NI 9853 are listed in
Tables 1 and 2.
Table 4 lists recommended termination resistor values.
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Table 1. Pin Assignments for CAN0
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 NC
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Table 2. Pin Assignments for CAN1
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 9853
You can connect each port of the NI 9853 to any location on a
CAN bus. Figure 2 shows one example of connecting CAN0 of
the NI 9853 directly to one CAN node, and CAN1 directly to
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