7-7
7 Tag Data Link Functions
NJ-series CPU Unit Built-in EtherNet/IP Port User’s Manual (W506)
7-1 Introduction to Tag Data Links
7
7-1-4 Overview of Operation
Create CPU Unit variables for input (consume) tags and output (produce) tags. You can create
up to 256 tags for a built-in EtherNet/IP port on an NJ-series CPU Unit. (There is a maximum
data size of 600 bytes (300 words) for each tag.) You can import and export network variables
that are created on the Sysmac Studio to CSV files. This allows you to register them as tags on
the Network Configurator. Output tags can be defined to clear output data to 0 or to hold the out-
put data from before the error when a fatal error occurs in the CPU Unit.
3
Setting Tag Sets
You can create output tag sets and input tag sets and assign tags to them. (You can create a
total of up to eight I/O tag sets.) You can create up to 32 tag sets for a built-in EtherNet/IP port
on an NJ-series CPU Unit. (The maximum data size of 1 tag set is 600 bytes (300 words).) You
can specify the Controller status in a tag set to indicate the CPU Unit’s operating status (operat-
ing information and error information).
4
Setting Connections
The target device output tag set and the originator device input tag set are associated as con-
nections. You can open a total of up to 32 connections for the built-in EtherNet/IP port.
Additional Information
Counting Connections
The number of connections is the total of the number of input tag sets that receive data and the
number of nodes that send data for output tag sets. (Refer to the following figure.) One connec-
tion is consumed for each connection setting whether the connection is a multi-cast connection
or a unicast (point-to-point) connection.
Setting the Requested Packet Interval (RPI)
The RPI is the data I/O refresh cycle on the Ethernet line when performing tag data links. The RPI
can be set separately for each connection. You can set the built-in EtherNet/IP port to between 10
and 10,000 ms (in 1-ms increments). The default setting is 50 ms. With EtherNet/IP, data is
exchanged on the communications line at the packet interval that is set for each connection, regard-
less of the number of nodes.
Setting Multi-cast and Unicast Communications
You can select a multi-cast connection or unicast (point-to-point) connection as the connection type
in the tag data link connection settings. With a multi-cast connection, you can send an output tag set
in one packet to multiple nodes and make allocations to the input tag sets. A unicast connection sep-
arately sends one output tag set to each node, and so it sends the same number of packets as the
number of input tag sets. Therefore, multi-cast connections can decrease the communications load
if one output tag set is sent to multiple nodes. If multi-cast connections are used, however, use a
Ethernet switch that has multi-cast filtering, unless the tag set is received by all nodes in the net-
work. If a Ethernet switch without multi-cast filtering is used, the multi-cast packets are broadcast to
Example for built-in EtherNet/IP port with IP address of 192.168.250.254 in
bidirectional connection with 16 nodes
Example of Calculating the Number of Connections
The maximum number of
connections for node
192.168.250.254 is 32.
192.168.250.254
Tagset_in1
Tagset_in2
Tagset_in16
Tagset_out32
CN.1
CN.2
CN.16
CN.17
CN.18
CN.32
192.168.250.1
Tagset_out
Tagset_in
192.168.250.2
Tagset_out
Tagset_in
192.168.250.16
Tagset_out
Tagset_in
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