CAN-8124/CAN-8224/CAN-8424 User Manual
CAN-8124/ CAN-8224/ CAN-8424 User Manual (Version 2.0, Aug/2007)
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Figure 3.1 DeviceNet layer
DeviceNet Communication Protocol is based on the concept of
connections. One must establish a connection with a device in order to
exclude information with that device. To establish a connection, each gateway
implements a Predefined Master/Slave Connection Set through the DeviceNet
network. After establishing the explicit connections, the connection is then
used to move information from one node to the other. Once IO connections
have been established, I/O data may be moved among devices in the network.
The 11-bit CAN identifier is used to identify the connection. DeviceNet defines
four separate groups of 11-bit CAN identifiers: Group 1, Group 2, Group 3, and
Group 4 described in Table 3.1. With respect to Connection Based Messages,
the Connection ID is placed within the CAN Identifier Field. With this in mind,
the below figure also describes the components for a DeviceNet Connection ID.
Because of the arbitration scheme defined by CAN, Group 1 messages have a
higher priority than group 2 messages and group 2 messages have higher
priority than group 3 messages and so on. This prioritization must be taken into
consideration when establishing connections.
Table 3.1 DeviceNet’s Use of the CAN Identifier Field
IDENTIFIER BITS
10 9 8 7 6 5 4 3 2 1
0
IDENTITY USAGE
HEX
RANGE
0
Group 1
Message ID
Source MAC ID
Group 1 Messages
000 –
3ff
1 0
MAC ID
Group 2
Message ID
Group 2 Messages
400 –
5ff
1 1
Group 3
Message ID
Source MAC ID
Message Group 3
600-7bf
1 1 1 1 1
Group 4 Message ID
Group 4 Messages
7c0–7ef
CAN-8124/CAN-8224/CAN-8424 provides the Predefined Master/Slave
Connection Set for users to establish connections. The Predefined
Master/Slave Connection Set is a set of Connections that facilitate
communications typically seen in a Master/Slave relationship. Many of the
steps involved in the creation and configuration of an application-to-application