12-2 Adjusting The Communications Load - Omron NX Series User Manual

12-2 Adjusting the Communications Load

In an Ethernet network using an Ethernet switch, the network bandwidth is not shared by all of the no-
des; independent transmission paths are established between individual nodes through the Ethernet
switch.
A dedicated communications buffer is established in the Ethernet switch for communications between
the nodes, and full-duplex communications (simultaneous transmission and reception) are performed
asynchronously with other transmission paths. The communications load in other transmission paths
does not affect communications, so packet collisions do not occur and stable, high-speed communica-
tions can be performed.
The Ethernet switch functions shown in the following table determine the performance of tag data
links.
Buffer capacity
Multicast filtering
QoS function
The following table shows the setting ranges of the tag data link settings that can be made for an
EtherNet/IP port.
Network bandwidth
Allowable tag data link communications
bandwidth
Connection resources
Packet interval
(RPI: Requested Packet Interval)
*1. When the Unit is performing tag data link communications where the allowable communications bandwidth
per Unit is close to or greater than 30,000 pps, the following functions may not be used properly. In that
case, use the built-in EtherNet/IP port on the CPU Unit or an EtherNet/IP port of a different NX-series Ether-
Net/IP Unit.
•
Connecting the Sysmac Studio online from the EtherNet/IP port of the NX-series EtherNet/IP Unit
•
Connecting the Network Configurator online from the EtherNet/IP port of the NX-series EtherNet/IP Unit
•
Connecting the NA-series Programmable Terminal online from the EtherNet/IP port of the NX-series
EtherNet/IP Unit
•
Port forward via the NX-series EtherNet/IP Unit
•
CIP message communications
•
SNMP function
These functions of the NX-series EtherNet/IP Unit can be used via X Bus from the built-in EtherNet/IP port
on the CPU Unit or an EtherNet/IP port of a different NX-series EtherNet/IP Unit.
When the tag data link settings exceed the capabilities of the Ethernet switch to be used, increase the
packet interval (RPI) value for adjustment.
Particularly when you configure the settings with an Ethernet switch that does not support multicast
filtering, you need to consider that multicast packets will be sent to all the nodes on the network with-
out setting the connections.
NX-series EtherNet/IP Unit User's Manual (W627)
12 Communications Performance and Communications Load
Item
This is the amount of data that can be buffered when packets ac-
cumulate at the Ethernet switch.
This function transfers multicast packets to specific nodes only.
This function performs priority control on packet transfers.
Item
Physical Ethernet baud rate
Maximum number of tag data link
packets that can be processed in 1
second (pps: packets per second)
Number of connections that can be
established
Refresh period for tag data
Description
Specification NX-series EtherNet/IP Unit
1,000 Mbps
40,000 pps max. (40,000
pps total for two ports)
256 max. (total of 512 with
two ports)
1.0 to 10,000 ms in 1.0-ms
increments
12
*1
12-7