slave.impl.h File Reference

Slave's types and basic functions (implementation) More...

#include "slave.h"
#include "slave_func.h"

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Functions
ModbusErrorInfo	modbusSlaveInit (ModbusSlave *status, ModbusRegisterCallback registerCallback, ModbusSlaveExceptionCallback exceptionCallback, ModbusAllocator allocator, const ModbusSlaveFunctionHandler *functions, uint8_t functionCount)
	Initializes slave device.
void	modbusSlaveDestroy (ModbusSlave *status)
	Frees memory allocated in the ModbusSlave struct.
ModbusErrorInfo	modbusBuildException (ModbusSlave *status, uint8_t function, ModbusExceptionCode code)
	Builds an exception response frame.
ModbusErrorInfo	modbusBuildExceptionPDU (ModbusSlave *status, uint8_t function, ModbusExceptionCode code)
	Builds an exception PDU.
ModbusErrorInfo	modbusBuildExceptionRTU (ModbusSlave *status, uint8_t address, uint8_t function, ModbusExceptionCode code)
	Builds a Modbus RTU exception.
ModbusErrorInfo	modbusBuildExceptionTCP (ModbusSlave *status, uint16_t transactionID, uint8_t unitID, uint8_t function, ModbusExceptionCode code)
	Builds a Modbus TCP exception.
ModbusErrorInfo	modbusParseRequest (ModbusSlave *status, const uint8_t *request, uint8_t requestLength)
	Parses provided PDU and generates response honorinng pduOffset and padding set in ModbusSlave during response generation.
ModbusErrorInfo	modbusParseRequestPDU (ModbusSlave *status, const uint8_t *request, uint8_t requestLength)
	Parses provided PDU and generates PDU for the response frame.
ModbusErrorInfo	modbusParseRequestRTU (ModbusSlave *status, uint8_t slaveAddress, const uint8_t *request, uint16_t requestLength)
	Parses provided Modbus RTU request frame and generates a Modbus RTU response.
ModbusErrorInfo	modbusParseRequestTCP (ModbusSlave *status, const uint8_t *request, uint16_t requestLength)
	Parses provided Modbus TCP request frame and generates a Modbus TCP response.

Variables
ModbusSlaveFunctionHandler	modbusSlaveDefaultFunctions []
	Associates function IDs with pointers to functions responsible for parsing. Length of this array is stored in modbusSlaveDefaultFunctionCount.
const uint8_t	modbusSlaveDefaultFunctionCount = sizeof(modbusSlaveDefaultFunctions) / sizeof(modbusSlaveDefaultFunctions[0]) - 1
	Stores length of modbusSlaveDefaultFunctions.

Detailed Description

Slave's types and basic functions (implementation)

Function Documentation

modbusBuildException()

ModbusErrorInfo modbusBuildException	(	ModbusSlave *	status,
		uint8_t	function,
		ModbusExceptionCode	code
	)

Builds an exception response frame.

Parameters

function	function that reported the exception
code	Modbus exception code

Returns

MODBUS_GENERAL_ERROR(ALLOC) on memory allocation failure

MODBUS_NO_ERROR() on success

Note

If set, exceptionCallback from ModbusSlave is called, even if the response frame is going to be discarded (when the request was broadcast).

Warning

This function expects ModbusSlave::response::pduOffset and ModbusSlave::response::padding to be set properly! If you're looking for a function to manually build an exception please use modbusBuildExceptionPDU(), modbusBuildExceptionRTU() or modbusBuildExceptionTCP()

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modbusBuildExceptionPDU()

ModbusErrorInfo modbusBuildExceptionPDU	(	ModbusSlave *	status,
		uint8_t	function,
		ModbusExceptionCode	code
	)

Builds an exception PDU.

Parameters

function	function that reported the exception
code	Modbus exception code

Returns

MODBUS_GENERAL_ERROR(ALLOC) on memory allocation failure

MODBUS_NO_ERROR() on success

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modbusBuildExceptionRTU()

ModbusErrorInfo modbusBuildExceptionRTU	(	ModbusSlave *	status,
		uint8_t	address,
		uint8_t	function,
		ModbusExceptionCode	code
	)

Builds a Modbus RTU exception.

Parameters

address	slave address to be reported in the excetion
function	function that reported the exception
code	Modbus exception code

Returns

MODBUS_GENERAL_ERROR(ADDRESS) if address is 0

MODBUS_GENERAL_ERROR(ALLOC) on memory allocation failure

MODBUS_GENERAL_ERROR(LENGTH) if the allocated response has invalid length

MODBUS_NO_ERROR() on success

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modbusBuildExceptionTCP()

ModbusErrorInfo modbusBuildExceptionTCP	(	ModbusSlave *	status,
		uint16_t	transactionID,
		uint8_t	unitID,
		uint8_t	function,
		ModbusExceptionCode	code
	)

Builds a Modbus TCP exception.

Parameters

transactionID	transaction ID
unitID	unit ID to be reported in the exception
function	function that reported the exception
code	Modbus exception code

Returns

MODBUS_GENERAL_ERROR(ALLOC) on memory allocation failure

MODBUS_GENERAL_ERROR(LENGTH) if the allocated response has invalid length

MODBUS_NO_ERROR() on success

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modbusParseRequest()

ModbusErrorInfo modbusParseRequest	(	ModbusSlave *	status,
		const uint8_t *	request,
		uint8_t	requestLength
	)

Parses provided PDU and generates response honorinng pduOffset and padding set in ModbusSlave during response generation.

Parameters

request	pointer to the PDU data
requestLength	length of the PDU (valid range: 1 - 253)

Returns

Any errors from parsing functions

Warning

This function expects ModbusSlave::response::pduOffset and ModbusSlave::response::padding to be set properly! If you're looking for a function to parse PDU and generate a PDU response, please use modbusParseRequestPDU() instead.

The response frame can only be accessed if modbusIsOk() called on the return value of this function evaluates to true.

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modbusParseRequestPDU()

ModbusErrorInfo modbusParseRequestPDU	(	ModbusSlave *	status,
		const uint8_t *	request,
		uint8_t	requestLength
	)

Parses provided PDU and generates PDU for the response frame.

Parameters

request	pointer to the PDU data
requestLength	length of the PDU (valid range: 1 - 253)

Returns

MODBUS_REQUEST_ERROR(LENGTH) if length of the frame is invalid

Any errors from parsing functions

Warning

The response frame can only be accessed if modbusIsOk() called on the return value from this function evaluates to true.

The requestLength argument is of type uint8_t and not uint16_t as in case of Modbus RTU and TCP.

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modbusParseRequestRTU()

ModbusErrorInfo modbusParseRequestRTU	(	ModbusSlave *	status,
		uint8_t	slaveAddress,
		const uint8_t *	request,
		uint16_t	requestLength
	)

Parses provided Modbus RTU request frame and generates a Modbus RTU response.

Parameters

slaveAddress	ID of the slave to match with the request
request	pointer to a Modbus RTU frame
requestLength	length of the frame (valid range: 4 - 256)

Returns

MODBUS_REQUEST_ERROR(LENGTH) if length of the frame is invalid

MODBUS_REQUEST_ERROR(CRC) if CRC is invalid

MODBUS_REQUEST_ERROR(ADDRESS) if the request is meant for other slave

MODBUS_GENERAL_ERROR(LENGTH) if the resulting response frame has invalid length

Any errors from parsing functions

Warning

The response frame can only be accessed if modbusIsOk() called on the return value of this function evaluates to true.

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modbusParseRequestTCP()

ModbusErrorInfo modbusParseRequestTCP	(	ModbusSlave *	status,
		const uint8_t *	request,
		uint16_t	requestLength
	)

Parses provided Modbus TCP request frame and generates a Modbus TCP response.

Parameters

request	pointer to a Modbus TCP frame
requestLength	length of the frame (valid range: 8 - 260)

Returns

MODBUS_REQUEST_ERROR(LENGTH) if length of the frame is invalid or different from the declared one

MODBUS_REQUEST_ERROR(BAD_PROTOCOL) if the frame is not a Modbus TCP message

MODBUS_GENERAL_ERROR(LENGTH) if the resulting response frame has invalid length

Any errors from parsing functions

Warning

The response frame can only be accessed if modbusIsOk() called on the return value of this function evaluates to true.

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modbusSlaveDestroy()

void modbusSlaveDestroy

(

ModbusSlave *

status

)

Frees memory allocated in the ModbusSlave struct.

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modbusSlaveInit()

ModbusErrorInfo modbusSlaveInit	(	ModbusSlave *	status,
		ModbusRegisterCallback	registerCallback,
		ModbusSlaveExceptionCallback	exceptionCallback,
		ModbusAllocator	allocator,
		const ModbusSlaveFunctionHandler *	functions,
		uint8_t	functionCount
	)

Initializes slave device.

Parameters

registerCallback	Callback function for handling all register operations (may be required by used parsing functions)
exceptionCallback	Callback function for handling slave exceptions (optional)
allocator	Memory allocator to be used (see modbusDefaultAllocator) (required)
functions	Pointer to array of supported function handlers (required). The lifetime of this array must not be shorter than the lifetime of the slave.
functionCount	Number of function handlers in the array (required)

Returns

MODBUS_NO_ERROR() on success

Warning

This function must not be called on an already initialized ModbusSlave struct.

See also

modbusDefaultAllocator()

modbusSlaveDefaultFunctions

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Variable Documentation

modbusSlaveDefaultFunctionCount

const uint8_t modbusSlaveDefaultFunctionCount = sizeof(modbusSlaveDefaultFunctions) / sizeof(modbusSlaveDefaultFunctions[0]) - 1

Stores length of modbusSlaveDefaultFunctions.

modbusSlaveDefaultFunctions

ModbusSlaveFunctionHandler modbusSlaveDefaultFunctions[]

Associates function IDs with pointers to functions responsible for parsing. Length of this array is stored in modbusSlaveDefaultFunctionCount.

Note

Contents depend on defined LIGHTMODBUS_FxxS macros!