Read Sunsynk Inverter values via RS232

[MartinViljoen]

I have a web front end that runs on an ESp32 and want to populate some values from the inverter , The TX and RX pins on the ESP32 is connected to a serial converter which is connected to the inverter's DB9 port.

I dont know how to request data and the documentation is not clear to me.

 

From the documentation i have this.

function code	Function code type	explain	remark
0x03	Public function code	Read the register	Contains reads to a single register and multiple registers
0x10	Public function code	write the register	Contains writes to a single register and multiple registers

 

2.6.1(0x03)

2.6.1 read register (function code: 0x03)

1            PDU         Request the PDU

 

data structure	data length	data range
function code	1 1 byte	0x03
Starting register address	2 2 byte	0x0000~0xFFFF
Number of registers	2 2 byte	0x0001~ 0x007D

2  PDU    Normal response PDU
2.6.1 read register (function code: 0x03)

data structure	data length	data range
function code	1 1 byte	0x03
byte count	1 1 byte	N×2
Register values	N×2 N×2 byte

N=    Note: N= number of registers

3  PDU         Abnormal response PDU

 

 107  3  PDU

Request to read out three consecutive register values starting at address 107 (describe PDU only) :

request		normal response		exceptional response
field name	●        field value	field name	field value	field name	field value
function code	0x03	function code	0x03	wrong code	0x83
Hi Starting address Hi	0x00	byte count	0x06	exception code	0x04
Lo Starting address Lo	0x6B	[107]Hi Register [107] Hi	0x02
Hi Number of registers Hi	0x00	[107]Lo Register [107] Lo	0x2B
Lo Register number Lo	0x03	[108]Hi Register [108] Hi	0x00
		[108]Lo Register [108] Lo	0x00
		[109]Hi Register [109] Hi	0x00
		[109]Lo Register [109] Lo	0x64

 

I tried sending some hex values to it but I dont get any response from the inverter it remains dead quiet.

Tried sending the below
 

  byte message[] = {0x03, 0x06};
  Serial.write(message, sizeof(message)); 

and also

  Serial.write(0x03);
  Serial.write(0x06);
  server.send(200, "text/plain", "message sent");

 

 

I tested and made sure that the ESP32 tx/rx pins are the correct way around,  by sending data back and forth using an USB-RS232 cable and putty. ESP and pc receives the data fine and the baud rate is correctly set to 9600

I'm convinced I'm not sending the correct request data.

 

Anyone care to assist ?