Rockwell Automation 1755-OF8 GuardPLC Controller Systems - Manual (Page 164)

164 Publication 1753-UM001C-EN-P - March 2010
Chapter 16 Peer-to-peer Communication Overview
Profile II: Medium
This profile provides medium-speed data throughput and covers
approximately 4% of all application cases. It is appropriate for
applications where timing is not a critical factor. With the Medium
profile, network media access within a token group and
communication with external token groups is controlled by token
passing. These external token groups must also run Medium profiles.
Using LAN Switches and Hubs
When using a hub instead of a LAN switch to interconnect two or
more controllers of the same token group, network access within the
token group is no longer conducted by the hardware, but must be
managed by token passing.
IMPORTANT
In the Medium profile, a token group must be comprised of at
least two controllers to carry out token passing, otherwise the
controller configuration is erroneous. (Stop/Invalid
Configuration).
Minimum Ethernet Network Requirements for Medium & Cleanroom
Requirement Definition
Medium 10 Mbps technology (10-Base T)
Hubs are used within the token groups and LAN switches connect one
token group to another.
Clean No loss of data due to traffic overload, harsh environmental
conditions, or network defects.
IMPORTANT
The network must not be shared with other applications. Do not
use more than one programming terminal (recommended).
programming terminals increase network traffic, but do not
participate in token passing.