Quick insert

[rhalf]

Your code on identifying coin won't work on the quick insert.
Wiring
DC12V (Red) Goes to your 12v supply.
COIN (White) Goes to pin A1 on your Arduino (this outputs 5v).
GND (Black) Goes to your common ground, yes it needs to ground on both your Arduino and the 12v power supply.
COUNTER (Grey) Leave it alone, ain't got a clue what it's for. #this part should give us signal whether that pulse is coming from the same coin. sadly it outputs the same signal as the coin pin.

please read this link for more information
http://blog.deconinck.info/post/2017/02/25/CH923/CH926/CH928-coin-acceptor-features-and-caveats