Rockwell Automation 1770 DH,DHII,DH485 CABLE - Manual (Page 12)

DH and DH+ Overview
Chapter 1
1-2
Devices Used on DH
Figure 1.1 shows devices that can be used on a DH network.
Important: The following illustration is intended only to depict the various
devices that can be used on a Data Highway network. You should not interpret
this illustration to be a representation of how to configure your DH network.
Figure 1.1
Devices that can be used on a DH network.
PLC-2
1771-KA2
1770-KF2
Computer
PLC-3
1775-S5
PLC-3
1775-KA
Pyramid Integrator
5130-RM1
1785-KA
To Data Highway Plus
Data Highway
1771-KE/KF
Personal
Computer
18661
Pyramid Integrator
5130-KA
1774 PLC
1774-KA
How Nodes Communicate on DH
A DH network uses peer-to-peer communication through a modified
token-passing scheme called floating master. The master controls access to
the network and can initiate messages at any time. With this arrangement,
nodesbid for temporary mastership based on their need to send information.
In this way, each node has equal access to become the master.