Espressif ESP32-S2 Programming Manual page 650

Chapter 2. API Reference
struct mb_param_request_t
Modbus register request type structure.
Public Members
uint8_t slave_addr
Modbus slave address
uint8_t command
Modbus command to send
uint16_t reg_start
Modbus start register
uint16_t reg_size
Modbus number of registers
Enumerations
enum mb_descr_type_t
Modbus descriptor table parameter type defines.
Values:
PARAM_TYPE_U8 = 0x00
Unsigned 8
PARAM_TYPE_U16 = 0x01
Unsigned 16
PARAM_TYPE_U32 = 0x02
Unsigned 32
PARAM_TYPE_FLOAT = 0x03
Float type
PARAM_TYPE_ASCII = 0x04
ASCII type
enum mb_descr_size_t
Modbus descriptor table parameter size in bytes.
Values:
PARAM_SIZE_U8 = 0x01
Unsigned 8
PARAM_SIZE_U16 = 0x02
Unsigned 16
PARAM_SIZE_U32 = 0x04
Unsigned 32
PARAM_SIZE_FLOAT = 0x04
Float size
PARAM_SIZE_ASCII = 0x08
ASCII size
PARAM_SIZE_ASCII24 = 0x18
ASCII24 size
PARAM_MAX_SIZE
enum mb_param_perms_t
Permissions for the characteristics.
Values:
Espressif Systems 639
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