7-9
7 Tag Data Link Functions
NJ/NX-series CPU Unit Built-in EtherNet/IP Port User’s Manual (W506)
7-1 Introduction to Tag Data Links
7
7-1-5 Starting and Stopping Tag Data Links
Precautions for Correct UsePrecautions for Correct Use
• 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) set-
tings. Refer to 14-2 Adjusting the Communications Load and set an appropriate packet inter-
val (RPI).
• If multi-cast connections are used, however, use an Ethernet switch that has multi-cast filter-
ing, unless the tag set is received by all nodes in the network. If an Ethernet switch without
multi-cast filtering is used, the multi-cast packets are broadcast to the entire network, and so
packets are sent to nodes that do not require them, which will cause the communications load
on those nodes to increase.
• If you will use data tag links with multicast at a communication speed over 100 Mbps, use an
Ethernet switch that supports a communication speed of 1000 Mbps.
If there is an Ethernet device on the same network that communicates at a speed of 100
Mbit/sec or less, the device may affect tag data link communication and cause tag data links to
be broken, even if the device is not related to tag data link communication.
• A maximum of 256 connections can be opened for an NX-series CPU Unit, and a maximum of
32 connections can be opened for an NJ-series CPU Unit. To calculate the number of connec-
tions of each connection type, refer to 14-1-2 Calculating the Number of Connections.
• If the maximum number of connections is exceeded, you must review the number of connec-
tions for the built-in EtherNet/IP port, or the number of nodes. When you use an NJ-series
CPU Unit, you can also consider adding EtherNet/IP Units.
Tag data links are automatically started when the data link parameters are downloaded from the Net-
work Configurator and the power supply to the NJ/NX-series Controller is turned ON. Thereafter, you
can start and stop tag data links for the entire network or individual devices from the Network Configu-
rator. Starting and stopping tag data links for individual devices must be performed for the originator.
Furthermore, you can use system-defined variables to start and stop the entire network. Refer to 7-2-12
Starting and Stopping Tag Data Links for details.
7-1-5 Starting and Stopping Tag Data Links
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