Allen-Bradley ControlLogix 1756-DH485, User Manual, Page: 40 / 110

Publication 1756-UM532A-EN-P - May 2006
3-8 Use Data Highway 485 Network
Programming Message Block Instructions in a Controller for Remote DH-485
Messaging
Before programming your message block instructions in your controller, you
must:
•
determine which links will send and receive remote DH-485 messaging.
•
draw a network to make sure you meet the design requirements for
remote DH-485 messaging.
If you are using remote DH-485 messaging, you must also:
•
assign link numbers.
The numbers must be a decimal value between 1-199. ControlLogix
chassis backplane may also be assigned link IDs.
•
assign DH-485 node numbers.
•
use RSLinx software to load routing tables into each 1756-DH485
module.
When using remote DH-485 messaging, you must include the following in the
message instruction:
•
Destination link ID - A user-defined number representing a network in
your system.
•
Remote node or slot - The node or slot on the remote network with
which you want to communicate.
If the message originates on a DH-485 network, you must also include a local
DH-485 node. The node on your local DH-485 network is capable of routing
the message. If the message originates on EtherNet/IP, ControlNet, or
ControlLogix, you must also include a CIP path to the first 1756-DH485
module.