Omron NJ501-1500, Connection Manual

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Terms and Definitions
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2. Terms and Definitions
Term Explanation and Definition
Node A controller and a device are connected to an EtherNet/IP network via
EtherNet/IP ports. EtherNet/IP recognizes each EtherNet/IP port
connected to the network as one node.
When a device with two EtherNet/IP ports is connected to the
EtherNet/IP network, EtherNet/IP recognizes this device as two nodes.
EtherNet/IP achieves the communications between controllers or the
communications between a controller and a device by exchanging data
between these nodes connected to the network.
Tag A minimum unit of the data that is exchanged on the EtherNet/IP network
is called a tag. The tag is defined as a network variable or as a physical
address, and it is assigned to the memory area of each device.
Tag set In the EtherNet/IP network, a data unit that consists of two or more tags
can be exchanged. The data unit consisting of two or more tags for the
data exchange is called a tag set. Up to eight tags can be configured per
tag set for OMRON controllers.
Tag data link In EtherNet/IP, the tag and tag set can be exchanged cyclically between
nodes without using a user program.
This standard feature on EtherNet/IP is called a tag data link.
Connection A connection is used to exchange data as a unit within which data
concurrency is maintained. The connection consists of tags or tag sets.
Creating the concurrent tag data link between the specified nodes is
called a "connection establishment". When the connection is
established, the tags or tag sets that configure the connection are
exchanged between the specified nodes concurrently.
There are two ways to specify the connection: one is to specify a tag set
name (tag name), and the other is to specify an instance number of
Assembly Object. In Sysmac Studio, the connection is set by specifying
the instance number.
Connection type There are two kinds of connection types for the tag data link connection.
One is a multi-cast connection, and the other is a unicast (point-to-point)
connection. The multi-cast connection sends an output tag set in one
packet to more than one node. The unicast connection separately sends
one output tag set to each node. Therefore, multi-cast connections can
decrease the communications load if one output tag set is sent to more
than one node.