Solax-DTSU666-Emulator

RS485 Emulator using XY-017 Auto Flow Control Module or similar

An ESP32-based DTSU666 smart meter emulator with automatic RS485 direction control for industrial IoT applications. Strongly influenced by Sungrow_DTSU666_emulator.

Features

• ESP32-optimized Modbus RTU implementation
• Automatic TX/RX switching with XY-017 module
• Victron MQTT OR ModbusTCP as data source
• OTA update option
• Status website

Hardware Requirements

• ESP32 development board
• XY-017 TTL to RS485 Converter (Auto Flow Control)
• RS485 bus wiring (A/B lines + GND)
• 3.3V power supply for XY-017 module

Wiring (ESP32 + XY-017)

ESP32	XY-017 Module
GPIO17 (TX2)	TXD
GPIO16 (RX2)	RXD
3.3V	VCC
GND	GND

Libraries Used

• ModbusRTU by [emelianov]
• ModbusTCP by [emelianov]
• PubSubClient by [Nick O'Leary]
• ArduinoJSON by [Benoit Blanchon]
• ESP32 Arduino Core (v2.0.0+)

ESP32 Specific Configuration

// settings.h
const int RX_PIN = 16;  // UART2 RX (GPIO16)
const int TX_PIN = 17;  // UART2 TX (GPIO17)

// Modbus Serial Configuration
const long modbusBaud = 9600;
const int SERIAL_CONFIG = SERIAL_8N1;

Installation

1. Clone this repository
2. Install required libraries through Arduino Library Manager
3. Copy settings.cpp.sample to settings.cpp and configure settings.cpp with your network and MQTT credentials
4. Upload to ESP32
5. Connect RS485 module to TTL pins (default: GPIO16-RX, GPIO17-TX)

Usage

1. Power up the device
2. Monitor serial port (115200 baud) for initialization status

MQTT Topics:

• smartmeter/data - Meter data in JSON format
• smartmeter/status - Device status (online/offline)

*** Victron topics need to be replaced. There are defined in settings.h. Using ModbusTCP is easier.

• victron/N/XXXXX/grid/YY/Ac/Energy/Forward
• victron/N/XXXXX/grid/YY/Ac/Energy/Reverse
• victron/N/XXXXX/grid/YY/Ac/Power
• victron/N/XXXXX/grid/YY/Ac/L1/Voltage
• victron/N/XXXXX/grid/YY/Ac/L2/Voltage
• victron/N/XXXXX/grid/YY/Ac/L3/Voltage
• victron/N/XXXXX/grid/YY/Ac/L1/Current
• victron/N/XXXXX/grid/YY/Ac/L2/Current
• victron/N/XXXXX/grid/YY/Ac/L3/Current
• victron/N/XXXXX/grid/YY/Ac/L1/Power
• victron/N/XXXXX/grid/YY/Ac/L2/Power
• victron/N/XXXXX/grid/YY/Ac/L3/Power
• victron/N/XXXXX/grid/YY/Ac/Frequency

Sample JSON Payload:

{
  "SML": {
    "total_kwh": 1234,
    "export_total_kwh": 789,
    "Power_curr": 1500,
    "volt_p1": 230,
    "volt_p2": 231,
    "volt_p3": 229,
    "freq": 50,
    "Power_A": 500,
    "Power_B": 600,
    "Power_C": 400
  }
}

Findings

After the Solax inverter reads Holding Register 0xB, it reads additional registers depending on the lowest byte. This suggests that it uses the content of 0xB to identify the smart meter type. After tinkering arround I found following behaviour:

• Register 0x000B (11) MeterType=0x0047 (327) Solax reads Register: 0x0028, Count: 2
• Register 0x000B (11) MeterType=0x0047 (327) Solax reads Register: 0x003E, Count: 2
• Register 0x000B (11) MeterType=0x0067 (104) Solax reads Register: 0x0106, Count: 2
• Register 0x000B (11) MeterType=0x00A0 (161) Solax reads Register: 0x000E, Count: 1
• Register 0x000B (11) MeterType=0x00A4 (165) Solax reads Register: 0x013E, Count: 1
• Register 0x000B (11) MeterType=0x00A6 (104) Solax reads Register: 0x2004, Count: 2 DDSU666(1phase) meter
• Register 0x000B (11) MeterType=0x00A7 (423) Solax reads Register: 0x2012, Count: 8 DTSU666(3phase) meter
• Register 0x000B (11) MeterType=0x00A8 (169) Solax reads Register: 0x000C, Count: 2
• Register 0x000B (11) MeterType=0x00AA (171) Solax reads Register: 0x2012, Count: 16 DTSU666(3phase) meter

Related Projects

For alternative implementations and community-driven approaches to Sungrow meter communication, you might want to explore:

• Sungrow-Meter-cheater
• Sungrow_DTSU666_emulator

Links

• Solax Modbus