SD750
POWER ELECTRONICS
10
ETHERNET/IP PROTOCOL
2.
ETHERNET/IP PROTOCOL
Ethernet/IP introduction
Ethernet/IP is an application layer protocol for industrial automation applications. It uses the standard
protocols TCP/IP and Ethernet to configure, access and control industrial automation devices.
Ethernet/IP provides a total integrated system from the industrial floor to the company network. It is a
network protocol highly appropriate for the industrial environment because it allows establishing real-
time communication between workstations and I/O devices.
Ethernet/IP adapts the Common Industrial Protocol (CIP) to standard Ethernet. CIP is based on abstract
object modeling. Every device in a CIP network is modeled as a collection of objects. This offers several
advantages for users and automation manufacturers, such as low-cost product development, usability,
simple integration of devices and networks, and interoperability among suppliers.
According to the CIP specification, an object provides an abstract representation of a particular
component within a product. Therefore, anything not described in object form is not visible through CIP.
CIP objects can have the following structured elements:
•
Classes
•
Instances
•
Attributes
Furthermore, objects may contain
services
offering a well-defined functionality. CIP (and thus
Ethernet/IP) separates between two standard types of messaging:
•
Explicit Messaging
(Class 3 and UCMM). Explicit messages are used within CIP for point-
to-point and client/server connections. They contain addressing and service information
causing execution of a specific service on a specific part of the network node. Services are
only available in this type of messaging.
•
Implicit Messaging
(Class 1). Implicit messages do not contain any transmission protocol in
their IO data, for instance there is not any address and/or service information. A dynamically
generated unique connection ID allows reliable identification. The data format has already
been specified in the EDS (Electronic data sheet) file previously. Thus, the efficiency of data
transmission is improved as the meaning of the data is already known.
2