Feature Of Ethernet/Ip Slave Units; Overview - Omron ERT1 Series Operation Manual

Feature of EtherNet/IP Slave Units

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Feature of EtherNet/IP Slave Units

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Overview

High-speed, High-capacity Data Exchange through Tag Data Links
Tag Data Link (Cyclic Communications) Cycle Time
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EtherNet/IP is an industrial multi-vendor network that uses Ethernet compo-
nents. The EtherNet/IP specifications are open standards managed by the
ODVA (Open DeviceNet Vendor Association), just like DeviceNet.
EtherNet/IP is not just a network between controllers; it is also used as a field
network. The EtherNet/IP Slave Unit have the following features.
The EtherNet/IP protocol supports implicit communications, which allows
cyclic communications (called tag data links in this manual) with EtherNet/IP
devices.
The default settings for remote I/O communications with the PLC are the
same as for previous Slaves, whereby real I/O is allocated for each node
address. One difference with previous Slaves is that an area for Smart Slave
status information can be allocated to the Smart Slaves within the IN Area of
the Master. This is in addition to real I/O. (Settings are performed using the
Network Configurator or explicit messages.)
Tag data links (cyclic communications) can operate at the cyclic period speci-
fied for each application, regardless of the number of nodes. Data is
exchanged over the network at the refresh cycle set for each connection, so
the communications refresh cycle will not increase even if the number of
nodes is increased, i.e., the synchronicity of the connection's data is pre-
served.
Since the refresh cycle can be set for each connection, each application can
communicate at its ideal refresh cycle. For example, a processes interlocks
can be transferred at high speed while the production commands and the sta-
tus monitor information are transferred at low speed.
Note The communications load to the nodes must be within the Units' al-
lowed communications bandwidth.
Note The CIP (Common Industrial Protocol) is a shared industrial protocol for the
OSI application layer. The CIP is used in networks such as EtherNet/IP, Con-
trolNet, and DeviceNet. Data can be routed easily between networks that are
based on the CIP, so a transparent network can be easily configured from the
field device level to the host level.
The CIP has the following advantages.
• Destination nodes are specified by a relative path, without fixed routing
tables.
• The CIP uses the producer/consumer model. Nodes in the network are
arranged on the same level and it is possible to communicate with
required devices whenever it is necessary.
The consumer node will receive data sent from a producer node when the
connection ID in the packet indicates that the node requires the data.
Since the producer can send the same data with the same characteristics
in a multicast (either multicast or unicast can be selected), the time
required for the transfer is fixed and not dependent on the number of con-
sumer nodes.
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