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Overview of Tag Data Links Section 6-1
If multicast connections are used, however, use a switching hub that has mul-
ticast filtering, unless the tag set is received by all nodes in the network.
If a switching hub that does not have multicast filtering is used, the multicast
packets will be broadcast to the entire network, and so packets will be sent to
nodes that do not require them, which will cause the communications load on
those nodes to increase.
This applies only if one output tag set is sent to multiple nodes using a multi-
cast connection with one packet, the connection type of the connections that
receive the output tag set is multicast, and the connection I/O types, packet
intervals (RPI), and timeout values are all the same.
Note The performance of communications devices is limited to some extent by the
limitations of each product’s specifications. Consequently, there are limits to
the packet interval (RPI) settings. Refer to 10-2 Adjusting the Communica-
tions Load and set an appropriate packet interval (RPI).
Starting and Stopping Tag Data Links
Tag data links are automatically started when the data link parameters are
downloaded from the Network Configurator. Thereafter, tag data links can be
stopped and started for the entire network or individual devices from the Net-
work Configurator. Starting and stopping tag data links for individual devices
must be performed for the originator.
Software switches in allocated words can also be used to start and stop tag
data links for the entire network. Refer to 6-2-13 Starting and Stopping Tag
Data Links for details.
6-1-3 Tag Data Link Functions and Specifications
Item Specification
Communications
type
Standard EtherNet/IP implicit communications (connection-
type cyclic communications)
Setting method After setting tags, tag sets, and connections with the Network
Configurator, the tag data link parameters must be down-
loaded to all devices in the EtherNet/IP network.
With a CJ2H-CPU6@-EIP or CJ2M-CPU3@ CPU Unit, a sym-
bol table can be created with the CX- Programmer and then
imported into the Network Configurator to allocate tags.
After the parameters are downloaded, the EtherNet/IP Units
are restarted to start the tag data links.
Tags Applicable CPU Unit data: CIO Area, DM Area, EM Area,
Holding Area, Work Area, and symbols. (See note.)
Number of words per tag: 20 max. (40 bytes) for CJ2M, 722
max. (1,444 bytes) for other CPU Units
Number of tags per Unit: 32 max. for CJ2M, 256 max. for other
CPU UNits
Note With the CJ2H-CPU6@-EIP or CJ2M-CPU3@, network
symbols (I/O allocation settings) created using the CX-
Programmer can be imported into the Network Configu-
rator.
Tag sets Number of tags per tag set: 8 max. (7 max. if PLC status is
included)
Number of words per tag set: 20 max. (40 bytes) for CJ2M,
722 max. (1,444 bytes) for other CPU Units
Number of tag sets per Unit: 32 max. for CJ2M, 256 max. for
other CPU Units
Connections Number of connections per Unit: 32 max. for CJ2M, 256 max.
for other CPU Units