Rockwell Automation 2708-DH5B2L_DH5B4L Attended Workstation - Manual (Page 27)

Chapter 2
Installing a Network
2–14
Figure 2.11
Large Network Configuration
Host M—W—C—W—C—W—C—W—W—C—C—W
W Workstation
S Submaster
C Concentrator
M Master
Indicates RS-232 or RS-422 connection
Indicates RS-485 backbone
Indicates a tributary
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Key:
All of the workstations, including Masters, Concentrators and Submasters,
are standard workstations which have been configured for their individual
roles in the network. A configuration parameter is changed to allow any
workstation to adopt a new role in the network. Each workstation is capable
of operating in both a data collection and a data communications mode.
A workstation which is being used as a Master, Concentrator, or
Submaster can perform data collection functions even while serving in
the communication network.
Alternate Communication Links
When installing large networks, you may consider redundant communication
links in order to protect against Host or Master workstation failures. This
involves establishing certain workstations as “Alternate Sub-Masters”.
Configuring a large network with Alternate Masters will allow the alternate
workstation to take over communication operations if the designated Master
becomes inoperable or is removed from the network. An Alternate Host
provides full redundancy for collection in the event of a Host failure.