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Rockwell Automation Publication 842E-UM001B-EN-P—April 2015
Chapter 3
EtherNet/IP overview
The encoder is an I/O adapter in the EtherNet/IP. It receives and sends explicit
and implicit messages either cyclic or on request (polled).
TCP/IP and UDP/IP
EtherNet/IP uses TCP/IP or UDP/IP for communication. (TCP is transmission
control protocol and UDP is user datagram protocol.)
Implicit messaging is used for real-time communication between a programmable
logic controller (PLC) and the encoder in EtherNet/IP. With implicit messaging
a connection is established between exactly two devices within the CIP to
transfer, for example, I/O data such as position or velocity from the encoder to
the PLC. Implicit messaging uses UDP/IP via port 2222. As a result, a fast data
rate is used.
Explicit messaging is used in EtherNet/IP for communication that does not need
to take place in real time. Explicit messaging uses TCP/IP; it is used, for example,
to transfer parameters from the PLC to the encoder.
MAC address
Devices that originate or use data on the network have factory-assigned media
access control (MAC) addresses for unique identification. The MAC address
(MAC ID) consists of 6 bytes. The first three bytes identify the manufacturer.
The last three bytes are unique to the device. An example of a MAC address is
00:00:BC:C9: D7:14.
Communication frame
EtherNet/IP is based on the standard ethernet FRAME. This contains the
ethernet header, the ethernet data and the ethernet trailer. The MAC addresses of
the receiver (destination address) and of the source (source address) are contained
in the ethernet header.
Transmission sequence
Data field
Trailer
Header
Destination
Address
Source
Address
46...1500 Byte
Summary of Contents for Rockwell Automation 842E-MIP Series
Page 1: ...842E EtherNet IP Absolute Encoder 842E SIP xxx 842E MIP xxx User Manual ...
Page 6: ...iv Rockwell Automation Publication 842E UM001B EN P April 2015 About this document Notes ...
Page 34: ...28 Rockwell Automation Publication 842E UM001B EN P April 2015 Chapter 4 Installation Notes ...
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