How does WS6318 enter sleep mode using DTR?

Legacy Legacy AirPrime modules
1

To enter sleep mode using DTR proceed as follow:
first configure properly UART:
AT+WHCNF=6,1
AT&W
AT+CFUN=1,1

select the sleep mode to use DTR:
AT+PSSLEEP=0

now by toggling DTR , the WS6318 will enter sleep mode immediatly