A-B 1756-HIST2G Module Rockwell Equipment History

Connections 

EtherNet/IP communication modules must connect to Ethernet nodes to communicate on the EtherNet/IP network. 

A connection is a point-to-point communication mechanism that is used to transfer data between a transmitter and a receiver. 

Connections can be logical or physical. 

Two connection types--TCP connections and CIP connections--are layered over each other each time data is transferred. 

The TCP connection is the first connection established. 

It is used for all EtherNet/IP communication and is required for all CIP connection use. 

One TCP connection supports multiple CIP connections and remains open. 

Established over TCP connections, EtherNet/IP CIP connections transfer data from an 

application running on one end-node (transmitter) to an application running on another end-node (receiver).

CIP connections are configured to use explicit or implicit message types. 

The message types support connected and unconnected connection types.

Typically, connected CIP messages are used to transfer data. Unconnected CIP messages are used, but they are only temporary.

The following graphic shows how connections are layered on each other when data is transferred over the EtherNet/IP network.

Common Industrial Protocol

(CIP) CIP™ is a messaging protocol for devices in industrial automation control systems. 

CIP is the application layer for the EtherNet/IP network. 

This protocol implements a relative path to send a message from the producing modules in a system to the consuming modules. 

CIP uses the Producer/Consumer networking model instead of a source/ destination (Primary/Secondary) 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, digital input modules are not polled by a controller. 

Instead, they produce their data either upon a change of state (COS) or at a requested packet interval (RPI).

The frequency of update depends upon the options that are 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. 

The controller can also produce data for other controllers to consume.

The produced and consumed data is accessible by multiple controllers over the Logix backplane and over the EtherNet/IP network. 

This data exchange conforms to the Producer/Consumer model.