Instruction Manual

Rockwell Automation Publication 1756-UM514C-EN-P - June 2014 35
Using the Data Highway Plus Network Chapter 2
Use Control and Information
Protocol (CIP) Messaging
Control and Information Protocol (CIP) is the communication mechanism on
ControlLogix chassis, ControlNet network and Ethernet with the Encapsulation
Protocol (EPIC) protocol.
Like DH+ messaging, CIP supports communication between devices on the
same link and physically separate links. However, CIP Messaging uses another
method to route messages than DH+ Messaging.
CIP uses a “relative path” concept for routing messaging. Because the message
itself, or the connection the message is sent on, contains the information required
to route the message, CIP messages do not require any routing table or link IDs.
For more information on paths, see Chapter 4
.
Devices such as ControlLogix devices, devices that use the ControlNet network,
and devices that use EPIC protocol on Ethernet support this new type of
communication.
Limitations of CIP Messaging
The 1756-DHRIO and 1756-DHRIOXT modules support 32 connections per
DH+ channel. A total of 5 of the connections can be CIP connections. These 5
count against the 32 connections. So if a 1756-DHRIO or 1756-DHRIOXT
module used 30 connections for DH+ Message Routing, it can use only 2
connections to bridge a CIP message through the module on that channel.
ControlLogix System 1
Node:0 01
ControlLogix System 2
1756-DHRIOControlLogix Controller
41289
1756-DHRIO
ControlLogix Controller
Node: 002
IMPORTANT
Your 1756-DHRIO and 1756-DHRIOXT modules support bridging CIP
messaging over a DH+ link. However, your 1756-DHRIO and 1756-DHRIOXT
modules do not support bridging CIP I/O data from a ControlLogix
controller to a 1756-I/O module.
The message originator, target, and all modules and links between them
must support CIP to send a message by using CIP protocol.