12 Rockwell Automation Publication 842E-UM001C-EN-P - September 2016
Chapter 2 Encoder Overview
Multi-turn units assign a unique digital output for each shaft position across
multiple shaft rotations and have high-resolution capability. Rockwell
Automation absolute encoders are available with an enclosure rating of NEMA
Type 4 and IP66, and various mounting options. Applications include steel
mills, overhead cranes, punch presses, transfer lines, oil rigs, wind mills,
machine tools, and packaging.
Sine-cosine
A sine-cosine encoder is a position transducer, which uses two sensors, each 90°
out of phase from each other. Sine-cosine encoders are able to be used directly
by the drive or squared to provide a conventional A quad B digital signal.
Therefore, the sine-cosine encoder can be used as an absolute, sine-cosine, or
incremental feedback device.
Single-turn vs. Multi-turn
Absolute encoders are either single-turn or multi-turn. Single-turn encoders are
used if the absolute position of the shaft for one revolution is required. Multi-
turn encoders are used if the absolute position is required for multiple shaft
revolutions.
842E Encoder Features
The 842E EtherNet/IP encoder features include:
• Support for the encoder profile 22h (0x22) defined in the Common
Industrial Protocol (CIP
™), according to IEC 61784-1
• Compatibility with star, linear, and Device Level Ring topology
• Robust nickel code disk for harsh ambient conditions
• Configurable resolution per revolution: 1 to 262,144
• High precision and availability
• Ball bearings are spaced 30 mm (1.18 in.) apart for longer life
• Face mount flange and servo flange/blind hollow shaft and through
hollow shaft
• 18-bit single turn resolution
• 30-bit total resolution multi-turn resolution
• Endless shaft
•ControlFLASH™ update compatible
IMPORTANT A Series A encoder cannot be updated to a Series B. A Series B encoder must
be purchased to update future firmware. Series A does not have
ControlFLASH update capability.
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