Allen-Bradley ControlLogix 1756-DH485, User Manual, Page: 19 / 110

1 Publication 1756-UM532A-EN-P - May 2006
Chapter
2
Overview of the DH-485 Network
Introduction
The information in this chapter will help you plan, install, and operate devices
on a DH-485 network. This chapter also contains information that describes
the DH-485 network functions, network architecture, and performance
characteristics.
DH-485 Network
Description
The DH-485 network passes information between devices on the plant floor.
The network monitors process parameters, device parameters, device status,
process status, and application programs to support data acquisition, data
monitoring, program upload/download, and supervisory control.
The DH-485 network offers:
•
interconnection of 32 devices.
•
multi-master capability.
•
token passing access control.
•
the ability to add or remove nodes without disrupting the network.
•
maximum network length of 1219 m (4000 ft)
(1)
.
For See
DH-485 Network Description 2-1
DH-485 Network Protocol 2-2
DH-485 Token Rotation 2-2
DH-485 Network Initialization 2-2
Devices that Use the DH-485 Network 2-3
1747-AIC Isolated Link Coupler for DH-485 2-4
1761-NET-AIC Advanced Interface Converter Product Overview 2-6
Operating Modes 2-6
Device Compatibility 2-6
1747-UIC USB to DH-485 Interface Converter 2-7
Example System Configuration 2-8
Important Planning Considerations 2-10
Additional Resources 2-13
(1) The network can be extended to 2,438 meters (8,000 feet) by connecting two AIC+ Advanced Interface
Converters (1761-NET-AIC). Refer to the AIC+ Advanced Interface Converter User Manual, publication number
1761-6.4.