CANopen Programmer's Manual - Maccon.de

1: Introduction CANopen Programmer’s Manual
Defining a Device: CANopen Objects and Object Dictionaries
Objects and Dictionaries
The primary means of controlling a device on a CANopen network is by writing to device
parameters, and reading device status information. For this purpose, each device defines a group
of parameters that can be written, and status values that can be read. These parameters and
status values are collectively referred to as the device's objects.
These objects define and control every aspect of a device’s identity and operation. For instance,
some objects define basic information such as device type, model, and serial number. Others are
used to check device status and deliver motion commands.
The entire set of objects defined by a device is called the device’s object dictionary. Every device
on a CANopen network must define an object dictionary, and nearly every CANopen network
message involves reading values from or writing values to the object dictionaries of devices on the
network.
Object Dictionary as Interface
The object dictionary is an interface between a device and other entities on the network.
CAN Network
Object
Dictionary
AccelNet
Amplifier
Sensor
Motor
18 Copley Controls
I/O
Feedback
Local Control
CANopen Profiles and the Object Dictionary
The CANopen profiles specify the mandatory and optional objects that comprise most of an object
dictionary. The Communication Profile specifies how all devices must communicate with the CAN
network. For instance, the Communication Profile specifies dictionary objects that set up a
device’s ability to send and receive messages. The device profiles specify how to access
particular functions of a device. For instance, the CANopen Profile for Drives and Motion Control
(DSP 402) specifies objects used to control device homing and position control.
In addition to the objects specified in the Application Layer and Communication Profile and device
profiles, CANopen allows manufacturers to add device-specific objects to a dictionary.