I just spent 2 days with try and error regarding the RS485 communication between a PIP 5048GK and a Pylontech US3000. The pinout from the quote was also the response from MPPsolar but did NOT work. After many attempts I made it work with the following setup:
Inverter PIP 5048GK <-> Pylontech US3000
Pin 3 <-> Pin 8
Pin 5 <-> Pin 7
Youda proposed in his off grid LAB a version with Pin3<->Pin1 and Pin5<->Pin2 but this wasn't working. According to my Pylontech manual only Pin7+8 are usable for RS485 and this seems to be true.
Hope this helps...