The ESI S1 has a COM port on the right with an RS485 bus for third-party monitoring, separate from the WIFI/4G port on the left. Helios reads and steers over the COM port while the inverter keeps reporting to Solarman. No LSE-3 needed.
Configure the gateway itself per the general Waveshare article. Below is only what is model-specific.
⚠️ DRAFT. Measured on an ESI 4K-S1 on 21/09/2026. Modbus TCP to Modbus RTU conversion inside the gateway is not validated yet.
1. Which models
ESI 3K-S1
3.68K-S1
4K-S1
4.6K-S1
5K-S1
6K-S1.
Tested on the 4K-S1. Pins from the ESI 3-6K-S1 manual, table 4.4.5-1.
💡 Not for the three-phase ESI T1. That range has a different COM layout and a built-in Ethernet port.
2. Wiring
Pin 2 UC-A → A
Pin 3 UC-B → B
Pin 12 GND → GND
Twisted pair for A and B, a third conductor for GND. 1000 m maximum.
💡 Leave every other pin alone. 4/5 battery RS485, 6/7 meter, 8/9 battery CAN, 13-17 DRM, 18/19 current transformer. A wrong pair gives no error, only silence.
💡 The two RJ45 sockets are the parallelling bus between inverters. No monitoring RS485 runs over them.
3. Settings on the inverter
1. System Settings > 6. Communication Addr.
Communication Addr.: 01
Baud Rate: 9600bps
These are the factory defaults. If they differ, match the gateway to the inverter, not the other way round.
💡 More than one inverter on the bus? Each needs its own address, otherwise two answer at once.
4. Settings on the gateway
Application Setting > Uart Setting
Baudrate: 9600
Data bits: 8
Parity: None
Stop: 1
485 selector switch: on
Press Apply after every change.
🚨 The gateway does not ship at 9600. A wrong baud rate gives no error, only time-outs. That looks like a dead inverter or a bad cable.
5. Check
Read 0x048D, grid voltage phase R, in steps of 0.1 V. Around 2300 at 230 V. If that is right, the wiring, baud rate and address are all right.
Also useful:
0x0484frequency, around 50000x0445serial number as text0x100B-0x100Eaddress, baud rate, stop bits and parity as the inverter itself uses them
The ESI S1 uses the Sofar V1.38 register map, the same one as G3 and HYD.
6. Not working?
Nothing answers → swap A and B. Then check the baud rate on both sides.
Bytes come back but they are wrong → baud rate or parity differs.
A different address answers → the address was changed, or a second inverter is on the bus.
TXD light stays dark → the 485 selector switch is off.
Everything reads, everything is zero → check
0x0404. A standby inverter answers politely and delivers nothing.