3
Data field
4
Trailer
The Ethernet data field consists of different protocols that are nested within each other:
•
The IP datagram is transported in the user data of the Ethernet data field.
•
TCP segment or UDP datagram are transported in the user data of the IP data‐
gram.
•
The CIP protocol is transported in the user data of the TCP segment or UDP
datagram.
1
2
3
IP-Header TCP/UDP-Header CIP-Header CIP-Daten
Figure 8: Ethernet data field
1
CIP protocol
2
TCP segment or UDP datagram
3
IP datagram
3.5 CIP object model
For network communication, EtherNet/IP uses an “object model”, in which all the
functions and data of a device are defined.
The most important terms are explained below:
Class
A class contains related objects of a device, organized into instances.
Instance An instance consists of various attributes, which describe the properties of this
instance. Different instances in a class have the same services and the same attrib‐
utes. They can, however, have different attribute values.
Attribute Attributes represent the data which a device makes available via EtherNet/IP. This
data contains the current values of a configuration or an input, for example. Typical
attributes are, e.g., configuration or status information.
Service Services are used to access classes or attributes of a class and to generate certain
events. These services perform specified actions, e.g., reading attributes.
Table 7: Example CIP object model
Class Instance Attribute Value
Code 23h 1h 0Ah 3FFFFFFFh
Designation
Position sensor
object
Class has one
instance
Current position
value
Example
3.5.1 Supported classes
The encoder supports the following classes of encoder profile 22h:
3 PRODUCT DESCRIPTION
18
O P E R A T I N G I N S T R U C T I O N S | AFS/AFM60 EtherNet/IP 8014213/1EF3/2021-12-08 | SICK
Subject to change without notice
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