Rockwell Automation 1794-AENTR_AENTRXT FLEX I/O Dual Port EtherNet/IP Adapter Modules - Manual (Page 11)

Publication 1794-UM066A-EN-P - February 2012
Overview of FLEX I/O and Your Redundant EtherNet/IP Adapter Module 3
What the Adapter Does The 1794-AENTR and 1794-AENTRXT adapters perform two primary tasks:
•
Control of real time I/O data (implicit messaging). The adapter serves as a
bridge between I/O modules and the network.
•
Support of messaging data for configuration and programming
information(explicit messaging).
Use of the Control and
Information Protocol (CIP) The 1794-AENTR and 1794-AENTRXT adapters use the Control and
Information Protocol (CIP). CIP is the application layer protocol specified for
EtherNet/IP, the Ethernet Industrial Protocol, as well as for ControlNet and
DeviceNet. It is a message-based protocol that implements a relative path to send
a message from the producing device in a system to the consuming devices.
The producing device contains the path information that steers the message
along the proper route to reach its consumers. Since the producing device holds
this information, other devices along the path simply pass this information; they
do not need to store it.
This has two significant benefits:
•
You do not need to configure routing tables in the bridging modules,
which greatly simplifies maintenance and module replacement.
•
You maintain full control over the route taken by each message, which
enables you to select alternative paths for the same end device.
Understanding the
Producer/Consumer Model The CIP producer/consumer networking model replaces the old
source/destination (master/slave) model. The producer/consumer model
reduces network traffic and increases speed of transmission. In traditional I/O
systems, controllers poll input modules to obtain their input status. In the CIP
system input modules are not polled by a controller. Instead, they produce
(multicast) their data either upon a change of state (COS) or periodically. The
frequency of update depends upon the options chosen during configuration and
where on the network the input module resides. The input module, therefore, is a
producer of input data and the controller is a consumer of the data.
L
5
5
7
2
EtherNet/IP network
E
N
2
T
R
Other
network
devices
A
E
N
T
R
FLEX
I/O
E
N
2
T
R
ControlLogix
I/O