Endat

EnDat, or Encoder Data Transmission, is a bidirectional digital interface used by encoders to transmit position data and additional sensor information to motion controllers, drives, or programmable logic controllers. It was developed to provide reliable, high-resolution data communication in industrial automation environments.

The protocol supports various data sets, including absolute or incremental position, temperature, diagnostics, and status information. Data can be transferred on demand or as part of a cyclic data stream, enabling flexible data handling for feedback control. EnDat includes error detection mechanisms to ensure data integrity, such as checksums or other protective coding techniques.

In typical deployments, the encoder hosts an on-board microcontroller that implements the EnDat protocol and responds to requests from a host device over a serial bidirectional link. The interface commonly uses a clock signal in combination with a data channel, and can be implemented over a single cable that also supplies power in many configurations. This setup allows compact, rugged integration in motors and drives used in harsh industrial environments.

EnDat has evolved through multiple generations, collectively referred to as EnDat 2.x, which expand data capacity, support extended data fields, and improve error handling and transfer modes. The 2.x family is widely supported across encoder manufacturers and motion-control vendors, and can be integrated with various fieldbuses and industrial networks via gateways or adapters.

Applications for EnDat include servo motors in CNC machines, robotics, automated assembly, and other precision motion systems. It is commonly compared with other digital encoder interfaces such as SSI and BiSS, offering high data density, robust communication, and flexible data formats for feedback control.