Rockwell Automation 1775-S5_SR5,D17756.5.5 User Manual PLC-3 FAMILY I/0 - Manual (Page 61)

Chapter
4
4-1
DH and DH+ Communication
This chapter introduces some of the concepts and terminology involved
with operating the scanner on a DH or DH+ communication.
The Allen-Bradley DH and DH+ links are communication networks for
industrial control applications. Both links consist of a central trunkline
cable that can be up to 10,000 feet long. This cable can link together as
many as 64 distinct communication points (or nodes) called stations
(Figure 4.1).
Each station consists of some type of processor and a station interface
module. The station interface module enables the processor to
communicate with other stations on the DH or DH+ link. The scanner is
the station interface module for PLC-3 family controllers. Table 4.A lists
combinations of station interface modules and controllers.
Chapter Objectives
Introduction