Rockwell Automation 1755-OF8 GuardPLC Controller Systems - Manual (Page 165)

Publication 1753-UM001C-EN-P - March 2010 165
Peer-to-peer Communication Overview Chapter 16
Each token group handles its token passing individually, depending
on user settings, CPU cycle times, network topology, and so forth.
This means that for two (or more) token groups, which are
exchanging data, Token passing is not synchronized, resulting in a
loss of messages between the Token Groups.
The illustration above shows an application, consisting of two token
groups. The token groups equipped with hubs require token passing
to coordinate network access within the token groups. The token
groups are interconnected via a LAN switch.
IMPORTANT
To minimize loss of messages, only one controller in a token
group is allowed to exchange data with exactly one controller
in a second token group. Furthermore, the overall number of
links between token groups is limited to eight.
GuardPLC 2000 GuardPLC 2000 GuardPLC 2000
Token Group 1 Token Group 2
10 Mbps Switch
Programming Terminal
GuardPLC 1200
Controller
10 Mbps Hub
GuardPLC
2000
Controllers
GuardPLC 2000
Controller
GuardPLC 1600 Controllers with
Integrated Ethernet Switch
GuardPLC 1800 Controller with
Integrated Ethernet Switch
GuardPLC 1200
Controller
GuardPLC 1200
Controller
GuardPLC 1200
Controller