Modbus Core

Classes
struct	ModbusSensorParam
	Defines the configuration parameters for an individual sensor. More...
struct	ModbusSlaveParam
	Global vector that stores the configuration and state of all discovered Modbus slaves. More...
struct	ModbusRequestInfo
	Context of an in-flight Modbus request. More...
struct	ResponseFormat
	Intermediate structure to pass data from the Modbus callback to tasks. More...
struct	SensorSchedule
	Planning element for sensor sampling. More...

Macros
#define	RX_PIN   13
	< Utilidades de memoria (memcpy).
#define	TX_PIN   12
	UART transmission pin for RS485.
#define	MAX_MODBUS_RESPONSE_LENGTH   256
	Maximum expected length for a Modbus response.

Enumerations
enum	DiscoveryOrder { DISCOVERY_GET_COUNT = 1 , DISCOVERY_GET_DATA_OFFSET = 255 , DISCOVERY_READ_SENSOR_PARAM = 8 }
	Special commands used during the sensor discovery phase. More...
enum	RequestType { REQUEST_UNKNOWN , REQUEST_DISCOVERY , REQUEST_SAMPLING }
	Classification of the purpose of a Modbus request. More...

Functions
void	addRequest (uint32_t token, uint8_t slaveId, uint8_t sensorId, uint8_t functionCode, RequestType type)
	Registers a new request in the circular buffer.
ModbusRequestInfo *	findRequestByToken (uint32_t token)
	Searches for a pending request by its token.
void	initScheduler ()
	Initializes or updates the scheduling list (Scheduler).
void	handleData (ModbusMessage response, uint32_t token)
	Callback executed upon receiving valid Modbus data.
void	handleError (Error error, uint32_t token)
	Callback executed when a Modbus error occurs.
bool	discoverDeviceSensors (uint8_t deviceId)
	Starts the discovery process for a specific device.
void	initialDiscoveryTask (void *pvParameters)
	One-shot task for the initial discovery of sensors.
void	DataRequestScheduler (void *pvParameters)
	Main task of the Scheduler.
bool	getSensorParams (uint8_t slaveId, uint8_t sensorID, uint16_t &startAddr, uint16_t &numRegs)
	Gets the configuration parameters of a specific sensor.
uint8_t	getRegistersPerChannel (uint8_t slaveId, uint8_t sensorID)
	Calculates the number of registers per channel for a sensor.
void	parseAndStoreDiscoveryResponse (const ResponseFormat &response, uint8_t slaveId)
	Parses the discovery response and updates the slave list.
void	EventManager (void *pvParameters)
	Event Manager task.

Variables
ModbusClientRTU	MB
	Global instance of the Modbus RTU client.
QueueHandle_t	queueRespuestas
	Queue for received Modbus responses.
QueueHandle_t	queueEventos_Peripheral
	Event queues to the EventManager (peripherals and scheduler).

Detailed Description

Overview

This module implements the Modbus RTU client (ESP32/TTGO) and the complete flow of:

• Initial sensor discovery on RS485 slaves.
• Periodic reading scheduling (Scheduler) based on each sensor's parameters.
• Response and error management with token correlation.
• Data formatting in payloads per sensor and aggregation in a LoRaWAN payload.

Structure and components

• Data and configuration
  • ModbusSensorParam, ModbusSlaveParam: sensor and slave definitions.
  • SensorSchedule: sampling scheduler entries.
  • ResponseFormat: internal response transport from callbacks.
• Requests and correlation
  • ModbusRequestInfo: asynchronous request tracking by token.
  • API: addRequest(), findRequestByToken(), DiscoveryOrder, RequestType.
• Main tasks
  • initialDiscoveryTask: sensor discovery.
  • EventManager: translates events into Modbus transactions and registers tokens.
  • DataRequestScheduler: generates sampling events according to scheduleList.
  • Callbacks: handleData and handleError.

Main API

• Data/Config: ModbusSensorParam, ModbusSlaveParam, SensorSchedule.
• Transport: ResponseFormat.
• Requests: ModbusRequestInfo, DiscoveryOrder, RequestType, addRequest(), findRequestByToken().
• Callbacks/Tasks: initialDiscoveryTask, handleData, handleError, EventManager, DataRequestScheduler.

Usage

Flow summary:

1) Modbus startup

• Initializes UART RS485 and ModbusClientRTU (timeout/begin).
• Registers callbacks: handleData(), handleError().
• Creates tasks: EventManager and DataRequestScheduler.
• Launches initialDiscoveryTask with devicesToQuery.

2) Discovery

• initialDiscoveryTask publishes order=DISCOVERY_READ_SENSOR_PARAM.
• EventManager sends read request (addr=0, qty=8) and registers token.
• handleData() parses and updates slaveList with parseAndStoreDiscoveryResponse().
• initScheduler() calculates scheduleList.

3) Periodic sampling

• DataRequestScheduler triggers REQUEST_SAMPLING according to nextSampleTime.
• EventManager queries getSensorParams() and sends read request with startAddress/numRegs.
• handleData() delivers registers to the next subsystem.

4) Modbus errors

• handleError(): handles TIMEOUT, increases consecutiveFails, removes inactive slaves and recalculates scheduler.
• Tokens are invalidated after processing.

Warnings and best practices:

• Ensure consistent layout of 8 parameter registers for discovery.
• Respect offset 3 for register data in Modbus RTU responses.
• Protect scheduleList access with schedulerMutex.
• Review MAX_* limits to avoid overflow in queues and tokens.

Macro Definition Documentation

RX_PIN

#define RX_PIN   13

< Utilidades de memoria (memcpy).

< Necesario para definiciones de tipos enteros de tamaño fijo (uint8_t, etc). < Estructura de datos para mapeo de sensores. < Utilizado para la generación de timestamps UNIX.

UART reception pin for RS485.

Enumeration Type Documentation

DiscoveryOrder

enum DiscoveryOrder

Special commands used during the sensor discovery phase.

Enumerator
DISCOVERY_GET_COUNT	Request item count.
DISCOVERY_GET_DATA_OFFSET	Offset to get specific data.
DISCOVERY_READ_SENSOR_PARAM	Command to read sensor parameters (registers 0..7).

RequestType

enum RequestType

Classification of the purpose of a Modbus request.

Enumerator
REQUEST_UNKNOWN	Unidentified request type.
REQUEST_DISCOVERY	Request related to hardware discovery.
REQUEST_SAMPLING	Request for periodic data reading.

Function Documentation

addRequest()

void addRequest	(	uint32_t	token,
		uint8_t	slaveId,
		uint8_t	sensorId,
		uint8_t	functionCode,
		RequestType	type )

Registers a new request in the circular buffer.

Parameters

token	Unique identifier.
slaveId	Slave ID.
sensorId	Sensor ID.
functionCode	Modbus function.
type	Request type.

DataRequestScheduler()

void DataRequestScheduler

(

void *

pvParameters

)

Main task of the Scheduler.

Periodically checks which sensors should be sampled and generates events for the EventManager.

discoverDeviceSensors()

bool discoverDeviceSensors

(

uint8_t

deviceId

)

Starts the discovery process for a specific device.

Parameters

deviceId

Modbus ID of the device to query.

Returns

true if the event was queued correctly, false otherwise.

EventManager()

void EventManager

(

void *

pvParameters

)

Event Manager task.

Centralizes requests from the queues (Scheduler and Peripheral) and converts them into actual Modbus transactions.

findRequestByToken()

ModbusRequestInfo * findRequestByToken

(

uint32_t

token

)

Searches for a pending request by its token.

Parameters

token

Token to search for.

Returns

Pointer to the ModbusRequestInfo structure or nullptr if it does not exist.

getRegistersPerChannel()

uint8_t getRegistersPerChannel	(	uint8_t	slaveId,
		uint8_t	sensorID )

Calculates the number of registers per channel for a sensor.

Returns

Number of registers or 0 if the sensor is not found.

getSensorParams()

bool getSensorParams	(	uint8_t	slaveId,
		uint8_t	sensorID,
		uint16_t &	startAddr,
		uint16_t &	numRegs )

Gets the configuration parameters of a specific sensor.

Parameters

slaveId	Slave ID.
sensorID	Sensor ID.
startAddr	Reference to return the start address.
numRegs	Reference to return the number of registers.

Returns

true if the sensor was found, false otherwise.

handleData()

void handleData	(	ModbusMessage	response,
		uint32_t	token )

Callback executed upon receiving valid Modbus data.

Parameters

response	Object with the raw response.
token	Token of the original request.

handleError()

void handleError	(	Error	error,
		uint32_t	token )

Callback executed when a Modbus error occurs.

Manages retry logic and removal of inactive slaves (Timeout).

Parameters

error	Error code.
token	Token of the failed request.

initialDiscoveryTask()

void initialDiscoveryTask

(

void *

pvParameters

)

One-shot task for the initial discovery of sensors.

Iterates over dispositivosAConsultar, launches discovery, and then self-deletes.

initScheduler()

void initScheduler

(

)

Initializes or updates the scheduling list (Scheduler).

Iterates through slaveList, calculates effective intervals based on channels and registers, and populates scheduleList. It is thread-safe using schedulerMutex.

parseAndStoreDiscoveryResponse()

void parseAndStoreDiscoveryResponse	(	const ResponseFormat &	response,
		uint8_t	slaveId )

Parses the discovery response and updates the slave list.

Decodes the 8 parameter registers and creates or updates the entry in slaveList.

Parameters

response	Raw data received.
slaveId	ID of the slave that responded.