What is the "COM" port of X1-lite-lv inverter used for？

The COM terminal is used for generator state detection, rapid shutdown and remote monitoring via DI/COM terminal, generator start-up via DO terminal, battery communication via BMS terminal, controlling the device response via DRM terminal, Meter and CT connection via METER/CT_1 and METER/CT_2 terminal, parallel connection via PAR_1 and PAR_2 terminal.