Enumerations
enum class	SensorValueType : uint8_t { RAW = 0x00 , U_WORD = 0x1 , U_DWORD = 0x2 , S_WORD = 0x3 , S_DWORD = 0x4 , BIT = 0x5 , U_DWORD_R = 0x6 , S_DWORD_R = 0x7 , U_QWORD = 0x8 , S_QWORD = 0x9 , U_QWORD_R = 0xA , S_QWORD_R = 0xB , FP32 = 0xC , FP32_R = 0xD }

Functions
uint16_t	server_frame_length (const uint8_t *frame, size_t size)

uint16_t	client_frame_length (const uint8_t *frame, size_t size)

void	log_unsupported_value_type (SensorValueType value_type)

std::optional< int64_t >	payload_to_number (const uint8_t *data, size_t size, SensorValueType sensor_value_type, uint8_t offset, uint32_t bitmask)
	Convert a raw response payload to a number.

std::optional< int64_t >	registers_to_number (const uint16_t *registers, size_t count, SensorValueType sensor_value_type)
	Reconstruct a number from register words (host byte order).

StaticVector< uint8_t, MAX_PDU_SIZE >	create_client_pdu (ModbusFunctionCode function_code, uint16_t start_address, uint16_t number_of_entities, const uint8_t *values=nullptr, size_t values_len=0)
	Create a modbus clinet pdu for reading/writing single/multiple coils/register/inputs.

bool	is_function_code_read (uint8_t function_code)

bool	is_function_code_write (uint8_t function_code)

bool	is_function_code_exception (uint8_t function_code)

bool	is_function_code_custom (uint8_t function_code)

uint8_t	server_frame_data_offset (const uint8_t *frame, size_t size)

uint8_t	client_frame_data_offset (const uint8_t *, size_t)

bool	value_type_is_float (SensorValueType v)

ModbusFunctionCode	modbus_register_read_function (ModbusRegisterType reg_type)

ModbusFunctionCode	modbus_register_write_function (ModbusRegisterType reg_type, bool multiple=false)

uint8_t	c_to_hex (char c)

uint8_t	byte_from_hex_str (const std::string &value, uint8_t pos)
	Get a byte from a hex string byte_from_hex_str("1122", 1) returns uint_8 value 0x22 == 34 byte_from_hex_str("1122", 0) returns 0x11.

uint16_t	word_from_hex_str (const std::string &value, uint8_t pos)
	Get a word from a hex string.

uint32_t	dword_from_hex_str (const std::string &value, uint8_t pos)
	Get a dword from a hex string.

uint64_t	qword_from_hex_str (const std::string &value, uint8_t pos)
	Get a qword from a hex string.

template<typename T >
T	get_data (const uint8_t *data, size_t buffer_offset)
	Extract data from modbus response buffer.

template<typename T >
T	get_data (const std::vector< uint8_t > &data, size_t buffer_offset)

bool	bit_from_packed (int bit, std::span< const uint8_t > data)
	Extract coil data from modbus response buffer Responses for coil are packed into bytes .

	ESPDEPRECATED ("Use bit_from_packed() instead. Removed in 2027.2.0", "2026.8.0") inline bool coil_from_vector(int coil

template<typename N >
N	mask_and_shift_by_rightbit (N data, uint32_t mask)
	Extract bits from value and shift right according to the bitmask if the bitmask is 0x00F0 we want the values frrom bit 5 - 8.

template<typename Container >
void	number_to_payload (Container &data, int64_t value, SensorValueType value_type)
	Append the Modbus register words for value to data.

std::optional< int64_t >	payload_to_number (std::span< const uint8_t > data, SensorValueType sensor_value_type, uint8_t offset, uint32_t bitmask)
	Convert a response payload span to number; std::nullopt if the payload is too short.

	ESPDEPRECATED ("Use the std::span overload returning std::optional<int64_t> instead. Removed in 2027.2.0", "2026.8.0") inline int64_t payload_to_number(const std

std::vector< uint16_t >	float_to_payload (float value, SensorValueType value_type)

Variables
std::span< const uint8_t >	data { return bit_from_packed(coil, data)

Enumeration Type Documentation

◆ SensorValueType

enum class esphome::modbus::helpers::SensorValueType : uint8_t

strong

Enumerator
RAW
U_WORD
U_DWORD
S_WORD
S_DWORD
BIT
U_DWORD_R
S_DWORD_R
U_QWORD
S_QWORD
U_QWORD_R
S_QWORD_R
FP32
FP32_R

Definition at line 66 of file modbus_helpers.h.

Function Documentation

◆ bit_from_packed()

bool esphome::modbus::helpers::bit_from_packed	(	int	bit,
		std::span< const uint8_t >	data )

inline

Extract coil data from modbus response buffer Responses for coil are packed into bytes .

coil 3 is bit 3 of the first response byte coil 9 is bit 2 of the second response byte

Parameters

coil	number of the cil
data	modbus response buffer (uint8_t)

Returns: content of coil register

Definition at line 202 of file modbus_helpers.h.

◆ byte_from_hex_str()

uint8_t esphome::modbus::helpers::byte_from_hex_str	(	const std::string &	value,
		uint8_t	pos )

inline

Get a byte from a hex string byte_from_hex_str("1122", 1) returns uint_8 value 0x22 == 34 byte_from_hex_str("1122", 0) returns 0x11.

Parameters

value	string containing hex encoding
position	offset in bytes. Because each byte is encoded in 2 hex digits the position of the original byte in the hex string is byte_pos * 2

Returns: byte value

Definition at line 126 of file modbus_helpers.h.

◆ c_to_hex()

uint8_t esphome::modbus::helpers::c_to_hex ( char c )

inline

Definition at line 116 of file modbus_helpers.h.

◆ client_frame_data_offset()

uint8_t esphome::modbus::helpers::client_frame_data_offset	(	const uint8_t *	,
		size_t	)

inline

Definition at line 64 of file modbus_helpers.h.

◆ client_frame_length()

uint16_t esphome::modbus::helpers::client_frame_length	(	const uint8_t *	frame,
		size_t	size )

Definition at line 46 of file modbus_helpers.cpp.

◆ create_client_pdu()

StaticVector< uint8_t, MAX_PDU_SIZE > esphome::modbus::helpers::create_client_pdu	(	ModbusFunctionCode	function_code,
		uint16_t	start_address,
		uint16_t	number_of_entities,
		const uint8_t *	values = nullptr,
		size_t	values_len = 0 )

Create a modbus clinet pdu for reading/writing single/multiple coils/register/inputs.

Parameters

function_code	the modbus function code to use. One of: READ_COILS READ_DISCRETE_INPUTS READ_HOLDING_REGISTERS READ_INPUT_REGISTERS WRITE_SINGLE_COIL WRITE_SINGLE_REGISTER WRITE_MULTIPLE_COILS WRITE_MULTIPLE_REGISTERS
start_address	coil/register/input starting address
number_of_entities	number of coils/registers/inputs to read/write
values	optional payload bytes to write (nullptr for read commands)
values_len	length of values array

Returns: PDU (function code + data, no address, no CRC)

Definition at line 200 of file modbus_helpers.cpp.

◆ dword_from_hex_str()

uint32_t esphome::modbus::helpers::dword_from_hex_str	(	const std::string &	value,
		uint8_t	pos )

inline

Get a dword from a hex string.

Parameters

value	string containing hex encoding
position	offset in bytes. Because each byte is encoded in 2 hex digits the position of the original byte in the hex string is byte_pos * 2

Returns: dword value

Definition at line 148 of file modbus_helpers.h.

◆ ESPDEPRECATED() [1/2]

esphome::modbus::helpers::ESPDEPRECATED	(	"Use bit_from_packed() instead. Removed in 2027.2.0"	,
		"2026.8.0"	)

◆ ESPDEPRECATED() [2/2]

esphome::modbus::helpers::ESPDEPRECATED	(	"Use the std::span overload returning std::optional<int64_t> instead. Removed in 2027.2.0"	,
		"2026.8.0"	) const

Definition at line 295 of file modbus_helpers.h.

◆ float_to_payload()

std::vector< uint16_t > esphome::modbus::helpers::float_to_payload	(	float	value,
		SensorValueType	value_type )

inline

Definition at line 331 of file modbus_helpers.h.

◆ get_data() [1/2]

template<typename T >

T esphome::modbus::helpers::get_data	(	const std::vector< uint8_t > &	data,
		size_t	buffer_offset )

Definition at line 190 of file modbus_helpers.h.

◆ get_data() [2/2]

template<typename T >

T esphome::modbus::helpers::get_data	(	const uint8_t *	data,
		size_t	buffer_offset )

Extract data from modbus response buffer.

Parameters

T	one of supported integer data types int_8,int_16,int_32,int_64
data	modbus response buffer (uint8_t)
buffer_offset	offset in bytes.

Returns: value of type T extracted from buffer

Definition at line 169 of file modbus_helpers.h.

◆ is_function_code_custom()

bool esphome::modbus::helpers::is_function_code_custom ( uint8_t function_code )

inline

Definition at line 34 of file modbus_helpers.h.

◆ is_function_code_exception()

bool esphome::modbus::helpers::is_function_code_exception ( uint8_t function_code )

inline

Definition at line 30 of file modbus_helpers.h.

◆ is_function_code_read()

bool esphome::modbus::helpers::is_function_code_read ( uint8_t function_code )

inline

Definition at line 14 of file modbus_helpers.h.

◆ is_function_code_write()

bool esphome::modbus::helpers::is_function_code_write ( uint8_t function_code )

inline

Definition at line 22 of file modbus_helpers.h.

◆ log_unsupported_value_type()

void esphome::modbus::helpers::log_unsupported_value_type ( SensorValueType value_type )

Definition at line 104 of file modbus_helpers.cpp.

◆ mask_and_shift_by_rightbit()

template<typename N >

N esphome::modbus::helpers::mask_and_shift_by_rightbit	(	N	data,
		uint32_t	mask )

Extract bits from value and shift right according to the bitmask if the bitmask is 0x00F0 we want the values frrom bit 5 - 8.

the result is then shifted right by the position if the first right set bit in the mask Useful for modbus data where more than one value is packed in a 16 bit register Example: on Epever the "Length of night" register 0x9065 encodes values of the whole night length of time as D15 - D8 = hour, D7 - D0 = minute To get the hours use mask 0xFF00 and 0x00FF for the minute

Parameters

data	an integral value between 16 aand 32 bits,
bitmask	the bitmask to apply

Definition at line 221 of file modbus_helpers.h.

◆ modbus_register_read_function()

ModbusFunctionCode esphome::modbus::helpers::modbus_register_read_function ( ModbusRegisterType reg_type )

inline

Definition at line 87 of file modbus_helpers.h.

◆ modbus_register_write_function()

ModbusFunctionCode esphome::modbus::helpers::modbus_register_write_function	(	ModbusRegisterType	reg_type,
		bool	multiple = false )

inline

Definition at line 102 of file modbus_helpers.h.

◆ number_to_payload()

template<typename Container >

void esphome::modbus::helpers::number_to_payload	(	Container &	data,
		int64_t	value,
		SensorValueType	value_type )

Append the Modbus register words for value to data.

Works with any container exposing push_back(uint16_t) (e.g. std::vector or StaticVector).

Definition at line 239 of file modbus_helpers.h.

◆ payload_to_number() [1/2]

std::optional< int64_t > esphome::modbus::helpers::payload_to_number	(	const uint8_t *	data,
		size_t	size,
		SensorValueType	sensor_value_type,
		uint8_t	offset,
		uint32_t	bitmask )

Convert a raw response payload to a number.

Parameters

data	payload with the data to convert
size	number of bytes available in data
sensor_value_type	defines if 16/32/64 bits or FP32 is used
offset	offset to the data in data
bitmask	bitmask used for masking and shifting

Returns: 64-bit number of the payload

Definition at line 108 of file modbus_helpers.cpp.

◆ payload_to_number() [2/2]

std::optional< int64_t > esphome::modbus::helpers::payload_to_number	(	std::span< const uint8_t >	data,
		SensorValueType	sensor_value_type,
		uint8_t	offset,
		uint32_t	bitmask )

inline

Convert a response payload span to number; std::nullopt if the payload is too short.

Definition at line 289 of file modbus_helpers.h.

◆ qword_from_hex_str()

uint64_t esphome::modbus::helpers::qword_from_hex_str	(	const std::string &	value,
		uint8_t	pos )

inline

Get a qword from a hex string.

Parameters

value	string containing hex encoding
position	offset in bytes. Because each byte is encoded in 2 hex digits the position of the original byte in the hex string is byte_pos * 2

Returns: qword value

Definition at line 158 of file modbus_helpers.h.

◆ registers_to_number()

std::optional< int64_t > esphome::modbus::helpers::registers_to_number	(	const uint16_t *	registers,
		size_t	count,
		SensorValueType	sensor_value_type )

Reconstruct a number from register words (host byte order).

Inverse of number_to_payload. Decodes the value at the start of the given span; advance the pointer to read successive values.

Parameters

registers	register values in host byte order
count	number of registers available in registers
sensor_value_type	defines if 16/32/64 bits or FP32 is used

Returns: 64-bit number of the registers

Definition at line 178 of file modbus_helpers.cpp.

◆ server_frame_data_offset()

uint8_t esphome::modbus::helpers::server_frame_data_offset	(	const uint8_t *	frame,
		size_t	size )

inline

Definition at line 50 of file modbus_helpers.h.

◆ server_frame_length()

uint16_t esphome::modbus::helpers::server_frame_length	(	const uint8_t *	frame,
		size_t	size )

Definition at line 10 of file modbus_helpers.cpp.

◆ value_type_is_float()

bool esphome::modbus::helpers::value_type_is_float ( SensorValueType v )

inline

Definition at line 83 of file modbus_helpers.h.

◆ word_from_hex_str()

uint16_t esphome::modbus::helpers::word_from_hex_str	(	const std::string &	value,
		uint8_t	pos )

inline

Get a word from a hex string.

Parameters

value	string containing hex encoding
position	offset in bytes. Because each byte is encoded in 2 hex digits the position of the original byte in the hex string is byte_pos * 2

Returns: word value

Definition at line 138 of file modbus_helpers.h.

Variable Documentation

◆ data

std::span<const uint8_t> esphome::modbus::helpers::data { return bit_from_packed(coil, data)

Definition at line 209 of file modbus_helpers.h.

Enumerations

Functions

Variables

Enumeration Type Documentation

◆ SensorValueType

Function Documentation

◆ bit_from_packed()

◆ byte_from_hex_str()

◆ c_to_hex()

◆ client_frame_data_offset()

◆ client_frame_length()

◆ create_client_pdu()

◆ dword_from_hex_str()

◆ ESPDEPRECATED() [1/2]

◆ ESPDEPRECATED() [2/2]

◆ float_to_payload()

◆ get_data() [1/2]

◆ get_data() [2/2]

◆ is_function_code_custom()

◆ is_function_code_exception()

◆ is_function_code_read()

◆ is_function_code_write()

◆ log_unsupported_value_type()

◆ mask_and_shift_by_rightbit()

◆ modbus_register_read_function()

◆ modbus_register_write_function()

◆ number_to_payload()

◆ payload_to_number() [1/2]

◆ payload_to_number() [2/2]

◆ qword_from_hex_str()

◆ registers_to_number()

◆ server_frame_data_offset()

◆ server_frame_length()

◆ value_type_is_float()

◆ word_from_hex_str()

Variable Documentation

◆ data