esphome-smg-ii

ESPHome configuration to monitor and control a ISolar/EASUN SMG II inverter via RS232

Supported devices

• ISolar SMG II
• EASUN SMG II
• PowMr POW-HVM5.5K-48V / POW-HVM5.5K-48V-P

Requirements

• ESPHome 2024.6.0 or higher.
• One half of an ethernet cable with RJ45 connector
• RS232-to-TTL module (MAX3232CSE f.e.)
• Generic ESP32 or ESP8266 board

Schematics

               RS232                     UART-TTL
┌──────────┐              ┌──────────┐                ┌─────────┐
│          │              │          │<----- RX ----->│         │
│          │<---- TX ---->│  RS232   │<----- TX ----->│ ESP32/  │
│  SMG-II  │<---- RX ---->│  to TTL  │<----- GND ---->│ ESP8266 │
│          │<---- GND --->│  module  │<-- 3.3V VCC -->│         │<--- VCC
│          │              │          │                │         │<--- GND
└──────────┘              └──────────┘                └─────────┘

RJ45 jack

Pin	Purpose	MAX3232 pin	Color T-568B
1	TX	P13 (RIN1)	White-Orange
2	RX	P14 (DOUT1)	Orange
3
4	VCC 12V	-	Blue
5
6
7
8	GND	P15 (GND)	Brown

Please be aware of the different RJ45 pinout colors (T-568A vs. T-568B).

MAX3232

Pin	Label	ESPHome	ESP8266 example	ESP32 example
P11 (DIN1)	TXD	tx_pin	GPIO4	GPIO16
P12 (ROUT1)	RXD	rx_pin	GPIO5	GPIO17
P16 (VCC)	VCC
P15 (GND)	GND

Installation

Use the esp32-example.yaml / esp8266-example.yaml as proof of concept:

# Install esphome
pip3 install esphome

# Clone this project
git clone https://github.com/syssi/esphome-smg-ii.git
cd esphome-smg-ii

# Create a secret.yaml containing some setup specific secrets
cat > secrets.yaml <<EOF
wifi_ssid: MY_WIFI_SSID
wifi_password: MY_WIFI_PASSWORD

mqtt_host: MY_MQTT_HOST
mqtt_username: MY_MQTT_USERNAME
mqtt_password: MY_MQTT_PASSWORD
EOF

# Validate the configuration, create a binary, upload it, and start logs
# If you use a esp8266 run the esp8266-examle.yaml
esphome run esp32-example.yaml

Protocol

The protocol is Modbus RTU via RS232.

Description	Unit	Res	Addr	Len	R/W	Values
Fault code		ULong	100	2	R
Warning code		ULong	108	2	R
Serial number		Ascii	186	12	R
Operation Mode		UInt	201	1	R	0: Power On 1: Standby 2: Mains 3: Off-Grid 4: Bypass 5: Charging 6: Fault
Effective mains voltage	0.1V	Int	202	1	R
Mains Frequency	0.01Hz	Int	203	1	R
Average mains power	1W	Int	204	1	R
Effective inverter voltage	0.1V	Int	205	1	R
Effective inverter current	0.1A	Int	206	1	R
Inverter frequency	0.01Hz	Int	207	1	R
Average inverter power	1W	Int	208	1	R	Positive numbers indicate inverter output Negative numbers indicate inverter input
Inverter charging power	1W	Int	209	1	R
Output effective voltage	0.1V	Int	210	1	R
Output effective Current	0.1A	Int	211	1	R
Output frequency	0.01Hz	Int	212	1	R
Output active power	1W	Int	213	1	R
Output apparent power	1VA	Int	214	1	R
Battery average voltage	0.1V	Int	215	1	R
Battery average Current	0.1A	Int	216	1	R
Battery average power	1W	Int	217	1	R
PV average voltage	0.1V	Int	219	1	R
PV average Current	0.1A	Int	220	1	R
PV average power	1W	Int	223	1	R
PV charging average power	1W	Int	224	1	R
Load percentage	1%	Int	225	1	R
DCDC Temperature	1°C	Int	226	1	R
Inverter Temperature	1°C	Int	227	1	R
Battery state of charge	1%	UInt	229	1	R
Battery average current	0.1A	Int	232	1	R	Positive number means charging Negative number means discharging
Inverter charging average current	0.1A	Int	233	1	R
PV charging average current	0.1A	Int	234	1	R
Output Mode		Uint	300	1	R/W	0: Single 1: Parallel 2: 3 Phase-P1 3: 3 Phase-P2 4: 3 Phase-P3
Output priority		Uint	301	1	R/W	0: Utility-PV-Battery 1: PV-Utility-Battery 2: PV-Battery-Utility
Input voltage range		Uint	302	1	R/W	0: Wide range 1: Narrow range
Buzzer mode		Uint	303	1	R/W	0: Mute in all situations 1: Sound when the input source is changed or there is a specific warning or fault 2: Sound when there is aspecific warning or fault 3: Sound when fault occurs
LCD backlight		Uint	305	1	R/W	0: Timed off 1: Always on
LCD automatically returns to the homepage		Uint	306	1	R/W	0: Do not return automatically 1: Automatically return after 1 minute
Energy-saving mode		Uint	307	1	R/W	0: Energy-saving mode is off 1: Energy-saving mode is on
Overload automatic restart		Uint	308	1	R/W	0: Overload failure will not restart 1: Automatic restart after overload failure
Over temperature automatic restart		Uint	309	1	R/W	0: Over temperature failure will not restart 1: Automatic restart after over-temperature fault
Overload transfer to bypass enabled		Uint	310	1	R/W	0: Disable 1: Enable
Battery Eq mode is enabled		Uint	313	1	R/W	0: Disable 1: Enable
Output voltage	0.1V	Uint	320	1	R/W
Output frequency	0.01Hz	Uint	321	1	R/W
Battery overvoltage protection point	0.1V	Uint	323	1	R/W
Max charging voltage	0.1V	Uint	324	1	R/W
Floating charging voltage	0.1V	Uint	325	1	R/W
Battery discharge recovery point in mains mode	0.1V	Uint	326	1	R/W
Battery low voltage protection point in mains mode	0.1V	Uint	327	1	R/W
Battery low voltage protection point in off-grid mode	0.1V	Uint	329	1	R/W
Battery charging priority		Uint	331	1	R/W	0: Utility priority 1: PV priority 2: PV is at the same level as the Utility 3: Only PV charging is allowed
Maximum charging current	0.1A	Uint	332	1	R/W
Maximum mains charging current	0.1A	Uint	333	1	R/W
Eq Charging voltage	0.1V	Uint	334	1	R/W
Battery equalization time	min	Uint	335	1	R/W	Range: 0~900
Equalization timeout exit	min	Uint	336	1	R/W	Range: 0~900
Two equalization charging intervals	day	Uint	337	1	R/W	Range: 1~90
Turn on mode		Uint	406	1	R/W	0: Can be turn-on locally or remotely 1: Only local turn-on 2: Only remote turn-on
Remote switch		Uint	420	1	R/W	0: Remote shutdown 1: Remote turn-on
Exit the fault mode		Uint	426		W	1: Exit the fault state (only when the inverter enters the fault mode, it could be available)
Rated Power	W	Uint	643	1	R

Known issues

None.

Debugging

If this example doesn't work out of the box for your device please update your configuration to enable the debug output of the UART component and increase the log level to the see outgoing and incoming serial traffic:

logger:
  level: DEBUG
  # Don't write log messages to UART0 (GPIO1/GPIO3) if the inverter is connected to GPIO1/GPIO3
  baud_rate: 0

uart:
  id: uart_0
  baud_rate: 9600
  tx_pin: ${tx_pin}
  rx_pin: ${rx_pin}
  debug:
    direction: BOTH
    dummy_receiver: false

References

• https://powerforum.co.za/topic/11341-i-want-to-know-protocol-used-in-isolar-smg-ii-5kw/