Read Inverter parameters / function code 0x04

[git-greatguy]

Hi,

I want to read resgisters from command 0x04.
Tried to modify existing code to fit my need but no luck at the moment.

I'm not a modbus specialist and i think commands i send to inverter is wrong. (calculated crc error ?).

Here is what i did so far.

added a new function code 0x04

#define MODBUS_FN_READSINGLEREG 0x03
#define MODBUS_FN_READSINGLEREG2 0x04 

added a new variable "regval" for this function code to store along with register which we want to read.
struct mqtt_status_register

{
	uint16_t regnum;
	String    mqtt_name;
        uint16_t regval;
};

#define SOFAR_REG_BMCV 0x10B3

Declaration of one register we want to read on this new function code
static struct mqtt_status_register mqtt_status_reads[] =

{
[...]
{ SOFAR_REG_BMCV, "max_charge_voltage", MODBUS_FN_READSINGLEREG2 },
}

modified function addstateinfo

int addStateInfo(String &state, uint16_t reg, String human, uint16_t regval)
{
	unsigned int	val;
	modbusResponse	rs;

	if(readSingleReg(SOFAR_SLAVE_ID, reg, &rs, regval))
		return -1;

	val = ((rs.data[0] << 8) | rs.data[1]);

	if (!( state == "{"))
		state += ",";

	state += "\"" + human + "\":" + String(val);
	return 0;
}

modified readSingleReg function ( i think this is here i missed something with crc)

int readSingleReg(uint8_t id, uint16_t reg, modbusResponse *rs, uint16_t regval)
{
	uint8_t	frame[] = { id, regval, reg >> 8, reg & 0xff, 0, 0x01, 0, 0 };

	return sendModbus(frame, sizeof(frame), rs);
}

Any help to get this working ? Ask me if you want more informations !

Thanks a lot.