EnDat 2.2 - Bidirectional interface for position measuring devices

Digital drive systems and position control loops with position measuring devices for data sampling require measuring equipment offering fast data transfer with high transmission integrity.
In addition, further data such as drive-specific characteristic values, correction tables etc. should be provided. To ensure high system reliability, the measuring devices should be integrated in error detection routines and offer diagnostic capabilities.

The EnDat 2.2 interface is a digital, bidirectional interface for measuring devices. It is able to output position values of incremental and absolute measuring devices and read and update information stored in the measuring device, as well as store new information. 4 signal cables are sufficient, due to the fact that the data transfer is serial. The data is transferred synchronous with the clock signal specified by the downstream electronics. The transmission type (position values, parameters, diagnostics ...) is selected via mode commands, received by the measuring device from the downstream electronics. As a purely serial interface, EnDat 2.2 is also suitable for safety applications.

EnDat 2.2 - Bidirectional interface for position measuring devices 1:
Signal cables and power supply for the EnDat 2.2 interface**

Incremental signals and ordering designation (HEIDENHAIN EnDat interfaces)**

Some encoders also provide incremental signals. These are usually used to increase the resolution of the position value, or to serve a second subsequent electronics unit.
Current generations of encoders have a high internal resolution, and therefore no longer need to provide incremental signals.

The order designation indicates whether an encoder outputs incremental signals:

**) Source: Dr. Johannes HEIDENHAIN GmbH

EnDat 2.2 - Bidirectional interface for position measuring devices 2:

Connection of HEIDENHAIN EnDat-interfaces to terminals of the EL503x series

Terminals of the EL503x series can only be connected to measuring instruments that support a clock frequency of 8 MHz. This corresponds to the order designation EnDat22.

Encoders with the ordering designation EnDat02 can be operated at 8 MHz on terminals of the EL503x series without incremental signals using an appropriate adapter cable.