Rockwell Automation 842E EtherNet/IP Absolute Encoder User Manual - Manual (Page 11)

Rockwell Automation Publication 842E-UM001A-EN-P May 2012 3
Chapter
2
Encoder overview
The 842E family of encoders uses EtherNet/IP technology to provide its data to
a programmable controller. These encoders include an embedded EtherNet/IP
switch to connect additional EtherNet/IP capable products in series and/or
support a device level ring (DLR) topology for ethernet media redundancy.
The 842E are ultra-high resolution encoders in single-turn and multi-turn
versions. These encoders have 18 bit single-turn resolution. The multi-turn has
an additional 12 bits for counting the number of revolutions.
Overview of the encoder What is an encoder?
Encoders can electronically monitor the position of a rotating shaft to measure
information such as speed, distance, RPM, and position. Rockwell Automation
offers a variety of light- and heavy-duty incremental and absolute encoders. Our
accessories help you easily install and efficiently use our encoders.
What are the different kinds of encoders?
Incremental
A simple and cost-effective solution for a wide variety of applications,
incremental encoders electronically monitor the position or speed of a rotating
shaft. Encoder feedback is compatible with programmable controllers, numerical
controllers, motion controllers, and other positioning systems. Rockwell
Automation offers light-duty and heavy-duty incremental encoders for differing
shaft loads. Ruggedized incremental encoders are available with an enclosure
rating of NEMA Type 4 and IP66. Incremental encoders are also available in
solid and hollow shaft models for a variety of mounting options. Applications
include: machine tools, packaging machinery, motion controls, robotics, and DC
drives.
Absolute
An absolute encoder has a unique digital output for each shaft position. The use
of absolute encoders assures that true position is always available, regardless of
power interruptions to the system. Absolute encoders can be single-turn or multi-
turn.