Device Type Modbus TCP (Ethernet) RS485
SunESS-5H ❌ ✅ ❌ SunESS-10H SunESS-15H SunESS-20H
For correct ethernet wiring: Follow the
Info RS485 Wiring For correct RS485 wiring: Follow the guidelines for RS485 wiring . If the wiring shown in the table below is incorrect, please let us know. There is no general consensus in the industry about the usage of A and B for the RS485 polarity, so it may be counterintuitive and opposite of what you might expect for some devices.
Sunwoda SunESS-H systems support external EMS integration using the PCS communication port, which provides RS485 (Modbus RTU) and CAN .RS485 RTU .
Located on the right side of the SunESS Control Module and labeled:
PCS Communication (RS485/CAN)
Pin Function Wire Color 1 RS485 A Orange-white 2 RS485 B Orange 3 NC Green-white 4 CANH Blue 5 CANL Blue-white 6 NC Green 7 Wakeup +5V Brown-white 8 Wakeup – Brown
Only Pin 1 (A) and Pin 2 (B) are used for RS485.
SunESS PCS Port EMS RTU Port
Pin 1 (A) ---------> RS485 A (D+)
Pin 2 (B) ---------> RS485 B (D-)
Twisted pair, shielded
24–18 AWG
Ground shield at one side only (typically EMS side)
120 Ω resistor installed on COM1 port When used in parallel systems, termination is applied only on the master unit .
Daisy-chain only (no star topology)
A ↔ A and B ↔ B must be consistent across devices
Ensure EMS termination is set appropriately (ON or off depending on your wiring)
Configuration is performed using the PowerLite app .
Connect to SunESS using Bluetooth/Wi-Fi
Enter the device settings
Open PCS Setting
Select the protocol: Default (INV-08)
Enables SunESS standard RS485/CAN protocol
This is required for EMS communication.
Note: Actual SunESS register maps are not included in the manufacturer manual and must be requested from Sunwoda or inverter/EMS vendor.
Typical working defaults:
Parameter Value Protocol Modbus RTU Baudrate 9600 or 19200 Data bits 8 Parity None Stop bits 1 Slave ID 1
Up to 3 cabinets can be connected in parallel.
COM0 → COM1 is used for internal SunESS communicationDaisy-chain between cabinets
Only the master SunESS communicates with the EMS
Connect the EMS RS485 lines to the master’s PCS port
Close inverter battery switch (if installed)
Close SunESS circuit breaker (MCB)
Hold Power button for ≥3 seconds
Display lights up and system boots
Poll the SunESS slave ID and receive valid Modbus responses
Report SOC, voltage, current, alarms, etc.
Display solid status LED (normal operation)
Common issues and checks:
A/B reversed → swap RS485 A/B
Termination missing → ensure 120 Ω installed at COM1
Wrong PCS protocol → select Default (INV-08)
Wrong Modbus settings → verify baud, parity, ID
COM0/COM1 cables not daisy-chained correctly
Slave cabinet not powered on
Incorrect master selection
Sunwoda SunESS | a-tronix Documentation
Wire RS485:
Pin 1 → EMS A
Pin 2 → EMS B
Install 120 Ω resistor on COM1
Configure PCS protocol = Default (INV-08)
Configure EMS Modbus settings
Power on SunESS
Verify Modbus communication
