User Manual
Table Of Contents
- 1756-UM532A-EN-P
- Important User Information
- Table of Contents
- Purpose of This Manual
- Preface
- 1756-DH485 Module Overview
- Overview of the DH-485 Network
- Introduction
- DH-485 Network Description
- DH-485 Network Protocol
- DH-485 Token Rotation
- DH-485 Network Initialization
- Devices that Use the DH-485 Network
- 1747-AIC Isolated Link Coupler for DH-485
- 1761-NET-AIC Advanced Interface Converter Product Overview
- Operating Modes
- Device Compatibility
- Misconception about the 1761-NET-AIC Converter
- 1747-UIC USB to DH-485 Interface Converter
- Example System Configuration
- Important Planning Considerations
- Additional Resources
- Use Data Highway 485 Network
- Use RSLinx Software to Create a Routing Table
- Communicate from an SLC 5/03 Controller to a Logix Controller over a DH-485 Network
- Communicate Between SLC Controllers over DH+ and DH485 Networks
- Communicate Between a PLC-5 Controller and a Remote SLC 5/03 Controller over Multiple DH-485 Networks
- Communicate from an SLC 5/05 Controller to an SLC 5/03 Controller over an EtherNet/IP Network
- Communicate to a SLC 5/03 Controller on a DH-485 Network
- Communicate from a Logix Controller to an SLC 5/03 Controller over EtherNet/IP and DH-485 Networks
- Specifications
- Troubleshoot the 1756-DH485 Module
- Index
- How Are We Doing?
- Rockwell Automation Support
- Backcover

Publication 1756-UM532A-EN-P - May 200 6
Overview of the DH-485 Network 2-13
Maximum Node Address Setting
The maximum node address parameter should be set as low as possible. This
minimizes the amount of time used in soliciting successors when initializing
the network. If all nodes are addressed in sequence from 0, and the maximum
node address is equal to the address of the highest addressed node, the token
rotation will improve by the amount of time required to transmit a solicit
successor packet plus the slot timeout value.
You cannot add any nodes to the network without affecting the response time.
On the other hand, since the time required to hold an open station address is
greater than the time required to pass a token, it can be useful to leave a
temporary device (such as a personal computer) connected if there is only one
such device. A solicit successor packet requires the same transmission time as
the token pass, but there is an added slot timeout period.
See your programming software user manual for the procedures to set node
addresses, controller baud rate, and maximum node addresses.
Maximum Number of Communicating Devices
SLC 500 fixed and SLC 5/01 controllers can be selected by two initiators
maximum at the same time. Using more than two initiators to select the same
SLC 500 fixed and SLC 5/01 controllers at the same time can cause
communication timeouts.
Additional Resources
Refer to the manuals listed in the table Devices that Use the DH-485 Network
on page 2-3.
IMPORTAN
T
The SLC 500 Series A (only) controllers set the maximum
node address to 31 when power is cycled increasing
initialization and response time of the network.