Deye/SunSynk/Sol-Ark - The 2 in 1 BMS port


On newer Deye/SunSynk/Sol-Ark inverter models and firmware, the BMS port is a "2 in 1 port" used for both RS485 and CAN communication. The inverter can read a battery via CAN while SolarAssistant reads the inverter via RS485 in the same port at the same time.

Known models

  • Newer Deye/SunSynk 5 kW models/firmware
  • Newer Deye/SunSynk 16 kW models/firmware
  • Newer Deye/SunSynk 3 phase models/firmware

How does it work?

The BMS port contains pins for both RS485 and CAN. It is possible due to the fact that RS485 only requires 3 pins and CAN only requires 2 pins.

RJ45 splitter

How to test it

The SolarAssistant cable only uses pin 1 - 3. You can temporarily unplug the battery CAN cable from the inverter BMS port and plug the SolarAssistant RS485 cable into the inverter BMS port to see if SolarAssistant can read your inverter. Be sure to click "Disconnect", then "Connect" in SolarAssistant. Once the test is complete, put the battery CAN cable back into the BMS port.

Permanent solution - RJ45 splitter

Use an RJ45 splitter that duplicates all pins in a port into two ports. Unfortunetely many RJ45 splitters available in electronic stores swap the pins around as they are intended to be used for networking purposes. In the picture below, we found the product on the left works while the one on the right doesn't.

We will add RJ45 splitters to our online store at the end of March 2023.

RJ45 splitter

Alternative solution - Crimp RS485 and CAN into one RJ45 plug

Using our RS485 self crimp USB cable you can additionally insert the battery CAN cable into the RJ45 plug when crimping the cable.


When using a RJ45 splitter, it might lead you to connect the RS485 pins into the battery in addition to the CAN pins. The battery might use those pins for a different purpose and disrupt SolarAssistant monitoring communication. The battery CAN cable should only connect the CAN pins to the battery.