The sinusoidal signals are digitized and evaluated 4-fold in the subsequent electronics, which results in a measuring step 1/4 the signal period of the encoder.

To attain smaller measuring steps the sinusoidal signals are interpolated before digitizing.

Absolute Measuring Signals
Absolute rotary encoders, with resolutions starting from 10 bits, and the LC 181 linear encoder, transmit the measuring signal through a synchronous-serial interface. Here the absolute position value is transmitted synchronous to a clock signal from the subsequent electronics.

Many of the absolute encoders with synchronous-serial data transmission are available either with the SSI interface or with the bidirectional EnDat interface developed by HEIDENHAIN. The EnDat interface permits the transmission of additional information such as operating parameters, parameters of the encoder, and parameters from the machine manufacturer.

Absolute measuring systems featuring the EnDat interface also provide incremental signals to minimize dead times in highly dynamic control systems.

Other benefits of the EnDat interface:

• One interface for absolute encoders.
  
• High reliability of transmission.
  
• Storage of all parameters of the absolute encoder relevant to the subsequent electronics for automatic commissioning.
  
• Support of monitoring and diagnostic functions, both before and during operation. This contributes to a high reliability of the absolute position value and increases the availability of the machine and its surrounding system.
  
  

Absolute rotary encoders are also available for parallel data transmission with resolutions up to 12 bits for up to 4096 position valves per revolution.