Controller Area Network (CAN) Interfaces
High-Speed CAN Hardware
High-speed CAN interfaces can communicate with devices using
transfer rates up to 1 Mb/s. Typical high-speed devices include antilock
brake systems, engine control modules, and emissions systems.
The Intel 80386EX microprocessor on an NI-CAN interface provides
the operating environment for the CAN protocol communications stack.
CAN specifies timing requirements to ensure reliable, deterministic bus
operation. In a typical system, a National Instruments CAN interface must
provide the necessary system responsiveness. Because the majority of the
CAN protocol executes on the embedded Intel 80386EX microprocessor
on NI CAN interfaces, you can achieve improved response to incoming
messages. Embedded CAN protocol stack execution also results in more
deterministic network performance because the onboard microprocessor
is dedicated to CAN communication activities.
Low-Speed/Fault-Tolerant CAN Hardware
Low-speed/fault-tolerant CAN interfaces can communicate with
devices up to 125 kb/s and offer transceivers with fault-tolerant
capabilities. Typical low-speed/fault-tolerant devices in an automobile
include comfort devices such as seat and mirror adjusters.
Single-Wire CAN Hardware
Single-wire CAN interfaces can communicate with devices at rates up
to 33.3 kb/s (88.3 kb/s in high-speed mode). Typical single-wire
devices within an automobile include comfort devices such as seat and
mirror adjusters.
CAN Programming
With NI-CAN software, you can import CAN channel database files
that use the Vector format (.dbc). A CAN frame can contain multiple
values. By importing scaling information from the database files, you
can easily convert these values into channels with engineering units
(such as °C or kPa). You can either import the scaling information
directly into an application or into Measurement & Automation
Explorer (MAX), where you can edit channels. Alternatively, you can
configure channels directly in MAX.
NI-CAN software provides two different application programming
interfaces (APIs) – channel and frame, with which you can develop
applications customized to your test and simulation requirements.
The channel API provides access to the CAN bus in easy-to-use
engineering units, using channels. Therefore, it is recommended for
customers who are new to NI-CAN. The channel API simplifies
multiple device integration and synchronization. With the frame API,
which provides lower-level access to the CAN bus, you can read and
write raw frames on the network. The frame API is recommended for
users that require low-level access to the CAN bus.
Software-Selectable CAN Hardware
You can configure the software-selectable CAN interface for high-speed,
low-speed/fault-tolerant, or single-wire CAN. Multiple-transceiver
hardware offers the perfect solution for applications that require a
combination of communications standards.
NI-CAN Communications Software
National Instruments ships CAN devices with NI-CAN software for
Windows 2000/NT/XP/Me/98. NI-CAN software includes device
drivers that you can use for application development and firmware that
runs on the embedded Intel 80386EX microprocessor. The
NI-CAN device drivers are full 32-bit drivers designed for
Windows 2000/NT/XP/Me/98. These device drivers are compatible
with NI LabVIEW and LabWindows/CVI as well as standard
programming environments such as Microsoft Visual C/C++, Borland
C/C++, and Visual Basic 6. The firmware implements time-critical
features provided by the NI-CAN software. NI-CAN software provides
flexible yet easy-to-use functions for configuration and I/O on CAN.
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