Rockwell Automation 1756-DHRIO_DHRIOXT ControlLogix Data Highway Plus-Remote I/O Communication Interface Module User Manual
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Rockwell Automation Publication 1756-UM514C-EN-P - June 2014
Chapter 2
Using the Data Highway Plus Network
1756-DHRIO and 1756-DHRIOXT modules enable devices, such as PLC-5s,
to use “DH+ Remote Addressing” for messaging.
You must use RSLinx to configure your routing table. For more information on
routing tables, see page
Programming Message Block Instructions in a Controller for Remote DH+ Messaging
Before programming your message block instructions in your controller, you
must perform the following:
•
Determine which links will send and receive remote DH++ messaging.
•
Draw a network to make sure you meet the design requirements for remote
DH+ messaging.
If you are using remote DH+ messaging, you must also perform the following:
•
Assign link numbers. The numbers must be a decimal value between 1-
199. ControlLogix chassis can also be assigned link IDs. Remember that
the programming terminal and channel A are the same physical link.
•
Assign DH+ node numbers.
•
Use RSLinx software to load routing tables into each 1756-DHRIO and
1756-DHRIOXT module.
When using remote DH+ 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 DH+, you must also include:
•
local DH+ node - The node on your local DH+ network capable of
routing the message.
If the message originates on Ethernet or ControlNet networks or ControlLogix
controllers, you must also include a CIP path to the first 1756-DHRIO and
1756-DHRIOXT modules.
Limitations of Remote DH+ Messaging
Remote DH+ Messages are encapsulated in CIP messages and sent on CIP
connections when they are sent across ControlNet, Ethernet, and the
ControlLogix chassis backplane. Resource limits are associated with CIP on the