modbus.c File Reference

Modbus functions. More...

#include "kosteus.h"

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Functions
unsigned char	check_own_address (unsigned char message[])
	Checks if the address in the received ModBus message is the same as the address of this device. More...
unsigned char	get_function (unsigned char *message)
	Retrieves the function code from the received ModBus message. More...
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...
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...
unsigned char	hex_to_ascii_hex (unsigned char response[], unsigned char length)
	Converts characters from Hex to ASCII-Hex. More...
unsigned char	ascii_hex_to_hex (unsigned char *message)
	Converts two ASCII-Hex characters into one Hex-character. 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	check_LRC (unsigned char *message, unsigned char length_of_message)
	Check the LRC in the received ModBus message. More...
unsigned char	create_response_message (unsigned char *response)
	Creates a response message.Not in use. 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...
void	create_diagnostic_response (unsigned int sub_function, unsigned int diagnostic_counter_value)
	Creates a response for ModBus Diagnostic query. More...
void	create_echo_of_query (unsigned char *message, unsigned char *length_of_response_hex)
	Creates an echo of the received ModBus query. More...
void	error_getting_message (unsigned char *s, unsigned char error_code)
	Sends a debug message based on a specific error. More...
void	transmit_response (unsigned char *send_pointer, unsigned char length)
	Transmits the response to a ModBus query. More...
void	clear_receive_buffer (void)
	Clears the receive buffer. More...
void	clear_response_buffer (void)
	Clears the response buffer. More...

Variables
unsigned char	message [MAX_LENGTH_OF_MESSAGE]
unsigned char	response [MAX_LENGTH_OF_MESSAGE]
unsigned char	response_in_ascii_hex [MAX_LENGTH_OF_MESSAGE]
unsigned char	length_of_ascii_hex_response
unsigned char *	send_pointer
volatile unsigned char	receive_buffer [MAX_LENGTH_OF_BUFFER]
unsigned char	received_character
unsigned int	number_of_points
unsigned	intstart_address
volatile unsigned char	nro_characters_received
int	previouse_received_character
unsigned int	start_address
unsigned char	length_of_response
unsigned char	length_of_message
unsigned char	modbuss_address
unsigned long int	receive_timeout
unsigned char	array_of_ascii_characters [16] = "0123456789ABCDEF"

Detailed Description

Modbus functions.

---

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[]

)

Checks if the address in the received ModBus message is the same as the address of this device.

---

Parameters

message

The received ModBus message.

Returns

OK if the address is the same. Otherwise FALSE.

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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_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_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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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
	)

Converts characters from Hex to ASCII-Hex.

---

Parameters

response	Array of characters to be converted.
length	Length of the array.

Returns

Quantity of generated ASCII-Hex characters. Value used to determine the length of the ModBus (ASCII-Hex)response.

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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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Variable Documentation

unsigned char array_of_ascii_characters[16] = "0123456789ABCDEF"

unsigned intstart_address

unsigned char length_of_ascii_hex_response

unsigned char length_of_message

unsigned char length_of_response

unsigned char message[MAX_LENGTH_OF_MESSAGE]

Totally received modbus frame

unsigned char modbuss_address

volatile unsigned char nro_characters_received

unsigned int number_of_points

int previouse_received_character

volatile unsigned char receive_buffer[MAX_LENGTH_OF_BUFFER]

unsigned long int receive_timeout

unsigned char received_character

unsigned char response[MAX_LENGTH_OF_MESSAGE]

Response frame to be sended to master

unsigned char response_in_ascii_hex[MAX_LENGTH_OF_MESSAGE]

unsigned char* send_pointer

unsigned int start_address