Rockwell Automation 1785-KA5P/B DHP COMM. ADAPATER MOD. - Manual (Page 8)

Overview of the 1785ĆKA5
Communication Adapter Module
Chapter 1
1-2
This section describes the DH+ and DH485 networks. For more
information on these networks, see the DH/DH+/DH485 Protocol and
Command Set reference manual (publication 1770-6.5.16).
DH+ Networks
DH+ is a baseband local area network (LAN) that allows peer-to-peer
communication among a maximum of 64 nodes. Each node has a unique
station address between 0–63 decimal and 0–77 octal. Use DH+ when you
want to connect a small number of nodes on a common link or with other
industrial networks as a part of a plant-wide CIM facility. DH+ features:
remote programming of PLC-2, PLC-3, and PLC-5 processors on your
network (using Allen-Bradley 6200 Series software)
direct connections to PLC-5 processors and industrial programming
terminals
easy reconfiguration and expansion if you want to add more nodes later
a communication rate of 57,600 bits per second
The DH+ implements peer-to-peer communication with a token-passing
scheme to rotate link mastership among its nodes. Since this method does
not require polling, it helps provide time-efficient reliable data transport.
The DH+ uses factory set timeouts to restart token-passing communication
if the token is lost because of a defective node.
DH+ and DH485 Networks