Rockwell Automation 2708-DH5B2L_DH5B4L Attended Workstation - Manual (Page 71)

A–B
7
Chapter
7–1
Network Design
Designing a network to connect fewer than 32 workstations is fairly straight
forward: select the best place for the Master Workstation to be, and then run
one single multi-dropped twisted pair cable through each workstation
location. The “Master” workstation is the workstation which communicates
to the host.
A simple network Configuration follows:
Figure 7.1
Simple Network Configuration
Host W—W—W—W—W—W—W—W—W
W Workstation
M Master
M
Indicates RS-232
Indicates RSS-485 backbone
No more than 32 workstations can be connected to the same network cable.
If more than 32 workstations are required, see the next section.
The last step of this network is to compare the actual cable distances between
each workstation with the distances described in Chapter 2.
Note: All references to RS-232 should be understood to mean RS-422 if the
workstation’s COM1 port was ordered as RS-422.
Installing a large network of workstations involves connecting together
smaller networks. Up to 31 smaller sub-networks may be attached to form a
large network. Each sub-network, in turn, may contain up to 32 workstations.
The network which connects all of the sub-networks is called the ‘backbone’
network. Each sub-network is referred to as a ‘tributary’ network. A
maximum of 1024 workstations may be connected in this fashion. There are
instances where a tributary network can improve performance even when
fewer than 32 workstations are on the network.
The workstation which is attached to the host is configured to as the
“Master”. Each workstation on the backbone network that connects to a
tributary network is configured as “Concentrator”. The workstation on the
tributary which attaches to the Concentrator is configured as a “Submaster”.
Networks of 32
Workstations or Less
Network Installation of
More than 32 Workstations