modbus.h

Go to the documentation of this file.

    /****************************** ModBus ASCII Frame **********************************
    *                                                                                   *
    *                                                                                   *
    *   |  START   |  ADDRESS  |  FUNCTION  |  DATA     |  LRC      |  END      |       *
    *   |  1 CHAR  |  2 CHARS  |  2 CHARS   |  n CHARS  |  2 CHARS  |  2 CHARS  |       *
    *                                                                                   *
    *                                                                                   *
    *************************************************************************************/



/* ModBus Error Counter definitions */
#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 IOP_OVERRUN_COUNTER 0X13 */  /* Not in use */

/* Added Counters (not ModBus) */
#define FIRST_START_INDICATOR 16
#define BOOT_COUNTER 20

/* Message parameters */
#define MAX_LENGTH_OF_MESSAGE 128
#define MAX_LENGTH_OF_BUFFER MAX_LENGTH_OF_MESSAGE*2

/* Quantities of Holding Registers */
#define QUANTITY_MEASUREMENT_REGISTERS 8
#define QUANTITY_OF_COUNTER_REGISTERS 3

/* Holding Register definitions */
#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

/* Counter value position in ModBus Response Message */ /* Needed when counters are read from holding registers */
#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

/* Query types */
#define MEDIAN_MEASUREMENT 1
#define REAL_TIME_MEASUREMENT 2
#define COUNTER_QUERY 3

#define LENGTH_OF_CLEAR_COUNTERS_QUERY 7

/* Status definitions for State Machine*/
enum
{
    WAIT,                   
    RECEIVE,                
    WAITING_NEXT_CHAR,      
    MESSAGE_RECEIVED,       /* Not in use */
    CHECK_END_COND,         
    CHECK_LRC,              
    CHECK_ADDRESS,          
    CHECK_FUNCTION,         
    GET_START_ADDRESS,      
    GET_NUMBER_OF_POINTS,   
    MAKE_RESPONSE_MESSAGE,  
    ERROR,                  
    DONE,                   
    TRANSMIT                
};

/* ModBus Message */
enum {
MODBUSS_ADDRESS_START               = 1,
MODBUSS_FUNCTION_START              = 3,
POSITION_OF_DATA_LENGTH             = 3, /* Not in use */
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
};


/* ModBus Functions */
enum
{
    READ_HOLDING_REGISTERS=0x03,            
    INFO=0x04,                              
    DIAGNOSTICS=0x08                        
};


/* ModBus sub functions for Diagnostics */
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, /* Not in use */
    RETURN_SLAVE_NAK_COUNT                  = 0x10, /* Not in use */
    RETURN_SLAVE_BUSY_COUNT                 = 0x11, /* Not in use */
    RETURN_BUS_CHARACTER_OVERRUN_COUNT      = 0x12,
    RETURN_IOP_OVERRUN_COUNT                = 0x13, /* Not in use */
    CLEAR_OVERRUN_COUNTER_AND_FLAG          = 0x14, /* Not in use */
    GET_CLEAR_MODBUS_PLUS_STATISTICS        = 0x15  /* Not in use */
};


/* Error Codes for ModBus Exception Response (First 4 are standard ModBus Exception Codes) */
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       
     };



/* Prototypes */
unsigned char create_response_message ( unsigned char *response );
void clear_receive_buffer(void);
void clear_response_buffer(void);
unsigned char check_LRC ( unsigned char *response, unsigned char length_of_message );
unsigned char calculate_LRC ( unsigned char *message, unsigned char nro_characters );
unsigned char calculate_response_LRC ( unsigned char *message, unsigned char nro_characters );

unsigned char ascii_hex_to_hex ( unsigned char *start_address);
unsigned char get_function ( unsigned char *message );
unsigned char check_own_address ( unsigned char *message );

void create_echo_of_query( unsigned char *message, unsigned char *length_of_response_hex );
void create_diagnostic_response ( unsigned int sub_function, unsigned int diagnostic_counter_value );
void create_exception_response ( unsigned char function, unsigned char error_condition );

unsigned int get_start_address_of_holding_registers ( unsigned char *message );
unsigned int get_number_of_points ( unsigned char *message );
void create_and_send_exception_response ( unsigned char function, unsigned char error_condition );
unsigned int get_sub_function ( unsigned char *message );
void transmit_response(unsigned char *send_pointer,unsigned char length);

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

void clear_receive_buffer(void);

void Fatal_error ( unsigned char error_code );
void error ( unsigned char error_code );
void error_getting_message ( unsigned char *message,unsigned char error_code );