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 the 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
Source MAC ID
1 1 1 1 1
Group 4 Message ID
The I-7242D 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 connection have been removed within the
Predefined Master/Slave Connection Set definition. This, in turn, presents the
means by which a communication environment can be established using less
network and device resources. The CAN Identifier Fields associated with the
Predefined Master/Slave Connection Set are shown in the table 3-2. The table
defines the Identifiers that are to be used with all connection based message
involved in the Predefined Master/Slave Connection Set and, as such, it also
attributes associated with Predefined Master/Slave Connection Objects.
Note: The Master is the device that gathers and distributes I/O data for the
process controller. Slaves are the devices from which the Master gathers I/O
data and to which the Master distributes I/O data.
I-7242D DeviceNet/Modbus RTU Gateway User's Manual, July 2006, Version 1.1
Group 1 Messages
Group 2 Messages
Source MAC ID
Group 3 Messages
Group 4 Messages
I-7242D user manual