What is the difference between synchronous and asynchronous BTL?

Synchronous

Synchronous operation for Balluff BTL transmitters with SSI interface means that the internal sampling cycle of the transmitter matches the external sampling cycle of the device that generates the clock pulses.

This mode is suitable for closed loop feedback systems where consistent and short timing is required for accurate feedback.

Asynchronous

Asynchronous operation means that the external sampling frequency is independent of the internal sampling frequency of the BTL converter. In this mode, the position sent by the transducer is more or less current depending on the external sampling point, and the position delay is not constant.

This mode is often used when precise synchronization with an external device is not required.