BMS 2nd cable only works with particular MPP Solar inverters which support BMS of particular Pylontech batteries, View BMS cable, Product Details from MPPSOLAR INC. on Alibaba.com
Jk Jikong Active Balancer Bms Gps Rs485 - Battery Accessories & Charger Accessories - Aliexpress
VE.Can to CAN-bus BMS cable - Victron Energy
Victron VE.Can to CAN-bus BMS type B Kabel-VIVECANZUCAN-BMS-B_Master