National Instruments NI-CAN, User Manual

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Chapter 1 Introduction
NI-CAN User Manual 1-10 ni.com
rate (bits per second) used for communication, as well as a method used to
transmit CAN frames onto the network.
For more information on object-oriented and CAN terminology, refer to the
Glossary .
NI-CAN Object Hierarchy
The basic model of the NI-CAN software architecture is a hierarchical
collection of objects (instances), each of which has attributes and methods.
The hierarchy shows relationships between various objects. In general, a
given object in the hierarchy has an “is used to access” relationship with all
objects above it in the hierarchy.
As an example, consider a CAN device network in which the network
interface of a host computer is physically connected to two devices, a
pushbutton and an LED, as shown in Figure 1-3.
Figure 1-3. Simple CAN Device Network Application
The pushbutton device transmits the state of the button in a CAN data frame
with standard arbitration ID 13. The frame data consists of a single
byte—zero if the button is off, one if the button is on. For an NI-CAN
application to obtain the current state of the pushbutton, it transmits a CAN
remote frame with standard arbitration ID 13. The pushbutton device
Network
Interface
User
Application
LED
Device
Pushbutton
Device
Arbitration ID 5
Data Frame
Arbitration ID 13
Data Frame
Arbitration ID 13
Remote Frame