Rockwell Automation 1779-KP3R DATA HIGHWAY II - Manual (Page 12)

Overview
Chapter 1
1-6
Data Highway II communication interfaces operate at different modes that
vary according the their relationship with the logical ring. The modes are:
In–ring mode, which is when the interface is a fully operational
member of the ring. It accepts messages, replies to them, and is ready
to send them.
Seeking–membership mode, which is when the interface is trying to
become a member of the ring so that it can send messages.
When we talk of communication on a Data Highway II network, it is
important to keep in mind the concept of a link. A Data Highway II link
is one section of trunkline, including nodes, that makes up a Data
Highway II network (figure 1.7); links are limited by length of the
trunkline. Nodes on different links are ‘‘off–link” with respect to each
other; nodes on the some link are ‘‘on–link” with respect to each other.
Figure 1.7
A Data Highway II Link
Node Node Node
Node Node
10997-I
You can expand your Data Highway II network with the help of two
Allen–Bradley 1779–KP5 communication interface modules configured
as bridges. In this case, you would have two Data Highway II links
(figure 1.8).