modbus.h File Reference

Header for modbus.c. More...

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Macros
#define	BUS_MESSAGE_COUNTER   0
#define	BUS_COMMUNICATION_ERROR_COUNTER   4
#define	EXCEPTION_ERROR_COUNTER   8
#define	SLAVE_MESSAGE_COUNTER   12
#define	BUS_CHARACTER_OVERRUN_COUNTER   16
#define	FIRST_START_INDICATOR   16
#define	BOOT_COUNTER   20
#define	MAX_LENGTH_OF_MESSAGE   128
#define	MAX_LENGTH_OF_BUFFER   MAX_LENGTH_OF_MESSAGE*2
#define	QUANTITY_MEASUREMENT_REGISTERS   8
#define	QUANTITY_OF_COUNTER_REGISTERS   3
#define	START_OF_MEDIAN_REGISTERS   0
#define	END_OF_MEDIAN_REGISTERS   8
#define	START_OF_REAL_TIME_REGISTERS   100
#define	END_OF_REAL_TIME_REGISTERS   108
#define	START_OF_COUNTER_REGISTERS   200
#define	END_OF_COUNTER_REGISTERS   203
#define	PLACE_OF_BOOT_COUNTER_HIGH   3
#define	PLACE_OF_BOOT_COUNTER_LOW   4
#define	PLACE_OF_EXCEPTION_ERROR_COUNTER_HIGH   5
#define	PLACE_OF_EXCEPTION_ERROR_COUNTER_LOW   6
#define	PLACE_OF_BUS_COMMUNICATION_ERROR_COUNTER_HIGH   7
#define	PLACE_OF_BUS_COMMUNICATION_ERROR_COUNTER_LOW   8
#define	MEDIAN_MEASUREMENT   1
#define	REAL_TIME_MEASUREMENT   2
#define	COUNTER_QUERY   3
#define	LENGTH_OF_CLEAR_COUNTERS_QUERY   7

Enumerations
enum	{   WAIT, RECEIVE, WAITING_NEXT_CHAR, MESSAGE_RECEIVED,   CHECK_END_COND, CHECK_LRC, CHECK_ADDRESS, CHECK_FUNCTION,   GET_START_ADDRESS, GET_NUMBER_OF_POINTS, MAKE_RESPONSE_MESSAGE, ERROR,   DONE, TRANSMIT }
enum	{   MODBUSS_ADDRESS_START = 1, MODBUSS_FUNCTION_START = 3, POSITION_OF_DATA_LENGTH = 3, MODBUS_REGISTER_START_ADDRESS_HI = 5,   MODBUS_REGISTER_START_ADDRESS_LOW = 7, MODBUSS_SUB_FUNCTION_HIGH = 5, MODBUSS_SUB_FUNCTION_LOW = 7, MODBUS_NRO_POINTS_HI = 9,   MODBUS_NRO_POINTS_LOW = 11 }
enum	{ READ_HOLDING_REGISTERS =0x03, INFO =0x04, DIAGNOSTICS =0x08 }
enum	{   CLEAR_COUNTERS_AND_DIAGNOSTIC_REGISTERS = 0x0A, RETURN_BUS_MESSAGE_COUNT = 0x0B, RETURN_BUS_COMMUNICATION_ERROR_COUNT = 0x0C, RETURN_SLAVE_EXCEPTION_ERROR_COUNT = 0x0D,   RETURN_SLAVE_MESSAGE_COUNT = 0x0E, RETURN_SLAVE_NO_RESPONSE_COUNT = 0x0F, RETURN_SLAVE_NAK_COUNT = 0x10, RETURN_SLAVE_BUSY_COUNT = 0x11,   RETURN_BUS_CHARACTER_OVERRUN_COUNT = 0x12, RETURN_IOP_OVERRUN_COUNT = 0x13, CLEAR_OVERRUN_COUNTER_AND_FLAG = 0x14, GET_CLEAR_MODBUS_PLUS_STATISTICS = 0x15 }
enum	{   ILLEGAL_FUNCTION = 0x01, ILLEGAL_DATA_ADDRESS = 0x02, ILLEGAL_DATA_VALUE = 0x03, SLAVE_DEVICE_FAILURE = 0x04,   NO_LF, MAX_SIZE_EXEEDED, LRC_ERROR, BAD_CHARACTER,   UNKNOWN_FUNCTION, UNKNOWN_STATE, UNKNOWN_ADDRESS, CHAR_RECEIVE_TIMEOUT,   ILLECAL_END_CONDITION, ILLECAL_SUB_FUNCTION, ILLEGAL_START_CHARACTER }

Functions
unsigned char	create_response_message (unsigned char *response)
	Creates a response message.Not in use. More...
void	clear_receive_buffer (void)
	Clears the receive buffer. More...
void	clear_response_buffer (void)
	Clears the response buffer. More...
unsigned char	check_LRC (unsigned char *response, unsigned char length_of_message)
	Check the LRC in the received ModBus message. More...
unsigned char	calculate_LRC (unsigned char *message, unsigned char nro_characters)
	Calculates LRC checksum from received ModBus message. More...
unsigned char	calculate_response_LRC (unsigned char *message, unsigned char nro_characters)
	Calculates LRC checksum for the response to be sended. Called only once. More...
unsigned char	ascii_hex_to_hex (unsigned char *start_address)
	Converts two ASCII-Hex characters into one Hex-character. More...
unsigned char	get_function (unsigned char *message)
	Retrieves the function code from the received ModBus message. More...
unsigned char	check_own_address (unsigned char *message)
void	create_echo_of_query (unsigned char *message, unsigned char *length_of_response_hex)
	Creates an echo of the received ModBus query. More...
void	create_diagnostic_response (unsigned int sub_function, unsigned int diagnostic_counter_value)
	Creates a response for ModBus Diagnostic query. More...
void	create_exception_response (unsigned char function, unsigned char error_condition)
	Creates a ModBus Exceprion Response message. Described in page 95 Modicon Modbus Protocol Reference Guide. More...
unsigned int	get_start_address_of_holding_registers (unsigned char *message)
	Retrieves the Start Address value for Holding Register reading. More...
unsigned int	get_number_of_points (unsigned char *message)
	Retrieves the Number of Points value for Holding Register reading. More...
void	create_and_send_exception_response (unsigned char function, unsigned char error_condition)
unsigned int	get_sub_function (unsigned char *message)
	Retrieves the sub function code from the received ModBus message. Is called only if function code is 0x08. More...
void	transmit_response (unsigned char *send_pointer, unsigned char length)
	Transmits the response to a ModBus query. More...
unsigned char	hex_to_ascii_hex (unsigned char *response, unsigned char length)
void	Fatal_error (unsigned char error_code)
	On fatal error executin comes here and watch dog will handle the reset. More...
void	error (unsigned char error_code)
void	error_getting_message (unsigned char *message, unsigned char error_code)
	Sends a debug message based on a specific error. More...

Detailed Description

Header for modbus.c.

---

Macro Definition Documentation

#define BOOT_COUNTER   20

#define BUS_CHARACTER_OVERRUN_COUNTER   16

#define BUS_COMMUNICATION_ERROR_COUNTER   4

#define BUS_MESSAGE_COUNTER   0

#define COUNTER_QUERY   3

#define END_OF_COUNTER_REGISTERS   203

#define END_OF_MEDIAN_REGISTERS   8

#define END_OF_REAL_TIME_REGISTERS   108

#define EXCEPTION_ERROR_COUNTER   8

#define FIRST_START_INDICATOR   16

#define LENGTH_OF_CLEAR_COUNTERS_QUERY   7

#define MAX_LENGTH_OF_BUFFER   MAX_LENGTH_OF_MESSAGE*2

#define MAX_LENGTH_OF_MESSAGE   128

#define MEDIAN_MEASUREMENT   1

#define PLACE_OF_BOOT_COUNTER_HIGH   3

#define PLACE_OF_BOOT_COUNTER_LOW   4

#define PLACE_OF_BUS_COMMUNICATION_ERROR_COUNTER_HIGH   7

#define PLACE_OF_BUS_COMMUNICATION_ERROR_COUNTER_LOW   8

#define PLACE_OF_EXCEPTION_ERROR_COUNTER_HIGH   5

#define PLACE_OF_EXCEPTION_ERROR_COUNTER_LOW   6

#define QUANTITY_MEASUREMENT_REGISTERS   8

#define QUANTITY_OF_COUNTER_REGISTERS   3

#define REAL_TIME_MEASUREMENT   2

#define SLAVE_MESSAGE_COUNTER   12

#define START_OF_COUNTER_REGISTERS   200

#define START_OF_MEDIAN_REGISTERS   0

#define START_OF_REAL_TIME_REGISTERS   100

Enumeration Type Documentation

anonymous enum

Enumerator
WAIT	Waiting for ModBus message
RECEIVE	Message is coming, but not received totally yet
WAITING_NEXT_CHAR	Inhibits main loop to handle partly received modbus frame
MESSAGE_RECEIVED
CHECK_END_COND	CR received and waiting for LF to be come
CHECK_LRC	Total message received and LRC is checked
CHECK_ADDRESS	Check if this message belongs to me
CHECK_FUNCTION	Check what is the modbus function
GET_START_ADDRESS	Get Start Address of Holding Registers
GET_NUMBER_OF_POINTS	Get Number of Points of Holding Registers
MAKE_RESPONSE_MESSAGE	Generate response message
ERROR	If an error occures in the received ModBus message
DONE	Message is received and the response is sent.
TRANSMIT	Transmit respoinse to master

anonymous enum

Enumerator
MODBUSS_ADDRESS_START
MODBUSS_FUNCTION_START
POSITION_OF_DATA_LENGTH
MODBUS_REGISTER_START_ADDRESS_HI
MODBUS_REGISTER_START_ADDRESS_LOW
MODBUSS_SUB_FUNCTION_HIGH
MODBUSS_SUB_FUNCTION_LOW
MODBUS_NRO_POINTS_HI
MODBUS_NRO_POINTS_LOW

anonymous enum

Enumerator
READ_HOLDING_REGISTERS	Read Holding Registers
INFO	Report Slave ID (Currently not implemented)
DIAGNOSTICS	Diagnostics

anonymous enum

Enumerator
CLEAR_COUNTERS_AND_DIAGNOSTIC_REGISTERS
RETURN_BUS_MESSAGE_COUNT
RETURN_BUS_COMMUNICATION_ERROR_COUNT
RETURN_SLAVE_EXCEPTION_ERROR_COUNT
RETURN_SLAVE_MESSAGE_COUNT
RETURN_SLAVE_NO_RESPONSE_COUNT
RETURN_SLAVE_NAK_COUNT
RETURN_SLAVE_BUSY_COUNT
RETURN_BUS_CHARACTER_OVERRUN_COUNT
RETURN_IOP_OVERRUN_COUNT
CLEAR_OVERRUN_COUNTER_AND_FLAG
GET_CLEAR_MODBUS_PLUS_STATISTICS

anonymous enum

Enumerator
ILLEGAL_FUNCTION	ModBus Exception Error code = 0x01
ILLEGAL_DATA_ADDRESS	ModBus Exception Error code = 0x02
ILLEGAL_DATA_VALUE	ModBus Exception Error code = 0x03
SLAVE_DEVICE_FAILURE	ModBus Exception Error code = 0x04
NO_LF	Message had CR but LF was not followed
MAX_SIZE_EXEEDED	Modbus message was too long
LRC_ERROR	LRC was calculated differently than was sent
BAD_CHARACTER	Character was not HEX digit
UNKNOWN_FUNCTION	Modbus function was not understand by this code
UNKNOWN_STATE	If fatal error occurs
UNKNOWN_ADDRESS	The ModBus message was sent to someone else
CHAR_RECEIVE_TIMEOUT	Character receive timeout occurs
ILLECAL_END_CONDITION	Character receive timeout occurs
ILLECAL_SUB_FUNCTION	Illegal Diagnostic subfunction
ILLEGAL_START_CHARACTER	No ":" character at the beginning of ModBus message. (Not used in main State Machine, only defined here)

Function Documentation

unsigned char ascii_hex_to_hex

(

unsigned char *

message

)

Converts two ASCII-Hex characters into one Hex-character.

---

Parameters

message

Pointer to two ASCII-Hex characters to be converted.

Returns

The generated Hex character.

Warning

The ASCII-Hex characters must be in an array sequentially.

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unsigned char calculate_LRC	(	unsigned char *	message,
		unsigned char	nro_characters
	)

Calculates LRC checksum from received ModBus message.

---

Parameters

message	The received ModBus message in ASCII-Hex.
nro_characters	Number of characters in the received ModBus message.

Returns

Calculated LRC value.

Warning

Must be noted that *message parameter must be in ASCII-Hex format without START- and STOP-characters.

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unsigned char calculate_response_LRC	(	unsigned char *	message,
		unsigned char	nro_characters
	)

Calculates LRC checksum for the response to be sended. Called only once.

---

Parameters

message	The response message in HEX.
nro_characters	Number of characters to be included in the calculation.

Returns

Calculated LRC value.

Warning

Must be noted that *message parameter must in Hex format.

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unsigned char check_LRC	(	unsigned char *	message,
		unsigned char	length_of_message
	)

Check the LRC in the received ModBus message.

---

Parameters

message	The received ModBus message.
length_of_message	Length of the received message.

Returns

OK if received messages LRC is correct. Otherwise FALSE.

Warning

Must be noted that *message parameter must in ASCII-Hex format with STAR- and STOP-characters..

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unsigned char check_own_address

(

unsigned char *

message

)

void clear_receive_buffer

(

void

)

Clears the receive buffer.

---

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void clear_response_buffer

(

void

)

Clears the response buffer.

---

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void create_and_send_exception_response	(	unsigned char	function,
		unsigned char	error_condition
	)

void create_diagnostic_response	(	unsigned int	sub_function,
		unsigned int	diagnostic_counter_value
	)

Creates a response for ModBus Diagnostic query.

---

Parameters

sub_function	The sub function value from the received query.
diagnostic_counter_value	Diagnostic counter value responding to the received query.

Warning

kovakoodattu Diagnostic function code

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void create_echo_of_query	(	unsigned char *	message,
		unsigned char *	length_of_response_hex
	)

Creates an echo of the received ModBus query.

---

Parameters

message	Pointer to the received ModBus query.
length_of_response_hex	Length of the query in Hex.

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void create_exception_response	(	unsigned char	function,
		unsigned char	error_condition
	)

Creates a ModBus Exceprion Response message. Described in page 95 Modicon Modbus Protocol Reference Guide.

---

Parameters

function	The ModBus function where the exception occurred.
error_condition	The condition why the error occurred (Standard ModBus Exception Error code).

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unsigned char create_response_message

(

unsigned char *

response

)

Creates a response message.Not in use.

---

Parameters

response

Pointer to response message.

Returns

The length of response message.

Warning

Not in use.!!! This function is never called.

Warning

mita tama oikein on ????

void error

(

unsigned char

error_code

)

void error_getting_message	(	unsigned char *	s,
		unsigned char	error_code
	)

Sends a debug message based on a specific error.

---

Parameters

s	Pointer to message that caused the error.
error_code	Specific error code.

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void Fatal_error

(

unsigned char

error_code

)

On fatal error executin comes here and watch dog will handle the reset.

---

Parameters

error_code

Error code for error definition.

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unsigned char get_function

(

unsigned char *

message

)

Retrieves the function code from the received ModBus message.

---

Parameters

message

Pointer to the received ModBus message.

Returns

The function code.

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unsigned int get_number_of_points

(

unsigned char *

message

)

Retrieves the Number of Points value for Holding Register reading.

---

Parameters

message

Pointer to the received ModBus message.

Returns

Number of Points value.

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unsigned int get_start_address_of_holding_registers

(

unsigned char *

message

)

Retrieves the Start Address value for Holding Register reading.

---

Parameters

message

Pointer to the received ModBus message.

Returns

Start Address value.

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unsigned int get_sub_function

(

unsigned char *

message

)

Retrieves the sub function code from the received ModBus message. Is called only if function code is 0x08.

---

Parameters

message

Pointer to the received ModBus message.

Returns

The sub function code.

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unsigned char hex_to_ascii_hex	(	unsigned char *	response,
		unsigned char	length
	)

void transmit_response	(	unsigned char *	send_pointer,
		unsigned char	length
	)

Transmits the response to a ModBus query.

---

Parameters

send_pointer	Response in ASCII-Hex without START- and STOP-characters.
length	Length of the response.

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