About SEN pin

[GlebDen]

According to the documentation, the SEN pin should be connected:

To select 2-wire operation, the SEN pin must be sampled high by the device on the rising edge of RST.
To select 3-wire operation, the SEN pin must be sampled low by the device on the rising edge of RST.

But in your examples this pin is not connected at all.
What did I miss?

[fpalfpal]

There is a pullup resisitor (fixed high) on SEN pin on Aliexpress si4703 boards, so it is safe to leave SEN unconnected,
and 2wire operation is activated