Configure KC868-A8 in ESPHome

[land88]

https://esphome.io/components/sensor/pulse_counter.html
here ESPHome showed MAX can use 8 channel for counter. maybe you need to set "count_mode". A8's input by Optocoupler circuit, so check your sensor pulse speed, whether is too fast.

I know this article, but that doesn't explain which pin is for input 0, 1, etc 
For Pin12 by exemple, what is the real input on K868-A8 ? 
I have only one Counter to install, I put it between GND and Input 0, but how to configure it ? PIN 12 : Nothing....

Thanks