Implementation of the EnDat Bidirectional Serial Communication Protocol

Data (measured values or parameters) can be transmitted bidirectionally between the position encoder and the EnDat protocol core.

The transceiver unit of the EnDat protocol core supports RS-485 differential signal transmission, and data transmission is synchronized with clock pulses generated by the sensing servo control system. The type of data transmitted (position values, parameters, or diagnostic information, etc.) is selected by mode commands sent from the EnDat protocol core to the encoder. The EnDat data interface is a bidirectional digital interface designed by HEIDENHAIN for encoders, offering a series of important advantages such as high performance, low cost, high quality, and support for advanced machine tool design principles [42-44].

To match the characteristic impedance of the lines, a 120Ω resistor must be added at the end of each differential data and clock line. Additionally, each line should have a 330pF capacitor to filter out high-frequency interference