CUI INC – Compact, low-power absolute rotary encoders offer 12- or 14-bit resolution


CUI’s Motion Group has introduced two new series of absolute rotary encoder modules for angle measurement in motor systems. The AMT21 and AMT23 encoders provide single-turn absolute position information in 12- or 14-bit resolution, accurate to ±0.2 mechanical degrees.

Both series of encoders are based on CUI’s proprietary capacitive sensing technology. The capacitive sensing method offers highly durable and accurate position feedback and is resistant to contamination by the dirt, dust and oil frequently encountered in motion applications.

The AMT21 series connects to a host controller via a high-speed RS-485 interface, while the AMT23 series has a Synchronous Serial Interface (SSI).

Housed in compact packages, the smallest is 39mm x 28mm x 10mm, the AMT21 and AMT23 feature a locking hub for easy installation. Mounting and alignment are also quick and easy, thanks to the modules’ One Touch ZeroTM feature.

Both models come with either radial or axial cable connections. The operation of the AMT21 and AMT23 modules may be configured via CUI’s AMT ViewpointTM software with configuration parameters that include the direction of rotation and the zero position.

Designed to mate with a broad range of motors, the AMT21 and AMT23 are also supplied as a kit which contains nine sleeve bore options ranging from 2mm to 8mm, two simple mounting tools, and one standard and one wide baseplate with multiple pre-drilled mounting hole patterns.


  • 8mA operating current at a supply voltage of 5V
  • Maximum speed:
    - 8krpm in 12-bit resolution
    - 4krpm in 14-bit resolution
  • Maximum measurement latency
    - 29μs in AMT21
    - 250ns in AMT23
  • Operating-temperature range: -40°C to 105°C


  • Industrial equipment
  • Robotics
  • Battery-powered devices
  • Automation equipment