Hondata

Is it possible to connect four LC1 wideband digitally to the digital input of the s300v3

I do not believe so. Each LC1 has a digital output, so the S300 would need 4 digital inputs.
The PLX works differently where the sensors are daisy chained so that up to 32 devices only use one serial input with each sensor as a channel.

LC1 do have both in and out serial connections for digital signal, so I would think it's possible but how with s300

I am wondering how to connect and display four LC1 wideband in SManager

So the LC1 daisy chains like the PLX. Currently it would not work as there is no specific support. We would need to get the serial specification and then purchase some more LC1s to implement the input.

I would really appreciate if you could implement this, THANKS