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IMR01Y09-E3
6. DeviceNet COMMUNICATION
6.1 Features and Functionality
One DeviceNet Network can have a maximum of 64 Media Access Control Identifiers (MAC ID:
Node address).
Network length changes with communication speed.
Maximum network length *
Communication
speed
Thick trunk length Thin trunk length
Maximum
drop length
Cumulative
drop length
125 kbps
500 m
156 m or less
250 kbps
250 m
100 m
6 m
78 m or less
500 kbps
100 m
39 m or less
* Maximum distance between nodes
Install termination resistors to both ends of a trunk line in DeviceNet.
Specification of termination resistor: 121
Ω
,
±
1 %, 1/4 W (Metal film resistance)
A DeviceNet node is modeled as a collection of objects.
The object model provides a template for organizing and implementing the Attributes (data),
Services and Behaviors of the components of a DeviceNet product.
This model has represented the construction of address designation to consist of four levels of
Node address (MAC ID), Object class ID, Instance ID and Attribute ID.
An address of this 4 level is used as an identification factor of data in Explicit message
communication.
Address Lowest
Highest
Node 0
63
Object class
1
65535
Instance 0
65535
Attribute 1
255
DeviceNet incorporates CAN (Controller Area Network). CAN defines the syntax or form of the
data movement. Data on DeviceNet is transmitted using CAN data frame.
Identifier
Control
Data (0 to 8 bytes)
CRC
CAN data frame
For details on the communication specification of DeviceNet, see DeviceNet specifications.
DeviceNet specifications are available from ODVA (Open DeviceNet Vendor Association).
URL: http://www.odva.org
ACK
RTR Bit
Start of Frame
End of Frame
