Eaton PowerXL DX-NET-DEVICENET, Руководство пользователя

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4 Commissioning
4.5 General information about the DeviceNet field bus system
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DX-NET-DEVICENET 02/14 MN04012005ZEN www.eaton.com
4.5 General information about the DeviceNet field bus system
The DeviceNet field bus system is based on a connection-oriented
communications model. In other words, data can only be exchanged using
specific connections assigned to the devices.
4.5.1 Object model
In DeviceNet, all the devices within a DeviceNet network are described with
a unique object model. Each specific device is defined with the help of
objects.
The object model's objects can be subdivided into three groups:
• Management objects,
• Connection objects,
• Application-specific objects.
4.5.1.1 Management objects
Management objects define DeviceNet-specific data and functions.
Every single DeviceNet device has to support these objects.
Identity Object
The Identity Object (Class Code 01
hex
) contains all the data required to
uniquely identify a node within the network, e.g., vendor ID, device type, and
product code. In addition, it contains a device's current status, serial number,
and product name.
Message Router Object
The Message Router Object (Class Code 02
hex
) provides access to all of a
device's classes and instances via explicit messages.
4.5.1.2 Connection Objects
Connection objects define the messages exchanged via DeviceNet.
DeviceNet Object
The DeviceNet Object (Class Code 03
hex
) specifies the configuration of a
device, as well as its physical connection to the DeviceNet network. Every
single device has to support this object. More specifically, the object
contains the device's MAC ID, its current configured baud rate, and other
pertinent information.
Connection Object
The Connection Object (Class Code 0x05
hex
) is supported by every single
DeviceNet device in at least one instance. This object defines the connection
to data via I/O messages or explicit messages, the path and length of
producer/consumer data, the CAN identifier used for the connection, the
corresponding watchdog timer, and the response in the event of a fault
scenario.