modbus.h
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/*
* Copyright © 2001-2008 Stéphane Raimbault <stephane.raimbault@gmail.com>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser Public License for more details.
*
* You should have received a copy of the GNU Lesser Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef _MODBUS_H_
#define _MODBUS_H_
#include <stdint.h>
#include <termios.h>
#include <arpa/inet.h>
#ifdef __cplusplus
extern "C" {
#endif
#define MODBUS_TCP_DEFAULT_PORT 502
#define HEADER_LENGTH_RTU 0
#define PRESET_QUERY_LENGTH_RTU 6
#define PRESET_RESPONSE_LENGTH_RTU 2
#define HEADER_LENGTH_TCP 6
#define PRESET_QUERY_LENGTH_TCP 12
#define PRESET_RESPONSE_LENGTH_TCP 8
#define CHECKSUM_LENGTH_RTU 2
#define CHECKSUM_LENGTH_TCP 0
/* It's not really the minimal length (the real one is report slave ID
* in RTU (4 bytes)) but it's a convenient size to use in RTU or TCP
* communications to read many values or write a single one.
* Maximum between :
* - HEADER_LENGTH_TCP (6) + slave (1) + function (1) + address (2) +
* number (2)
* - HEADER_LENGTH_RTU (0) + slave (1) + function (1) + address (2) +
* number (2) + CRC (2)
*/
#define MIN_QUERY_LENGTH 12
/* Page 102, Application Notes of PI–MBUS–300:
* The maximum length of the entire message must not exceed 256
* bytes.
*/
#define MAX_MESSAGE_LENGTH 256
#define MAX_STATUS 800
#define MAX_REGISTERS 100
#define REPORT_SLAVE_ID_LENGTH 75
/* Time out between trames in microsecond */
#define TIME_OUT_BEGIN_OF_TRAME 500000
#define TIME_OUT_END_OF_TRAME 500000
#ifndef FALSE
#define FALSE 0
#endif
#ifndef TRUE
#define TRUE 1
#endif
#ifndef OFF
#define OFF 0
#endif
#ifndef ON
#define ON 1
#endif
/* Function codes */
#define FC_READ_COIL_STATUS 0x01 /* discretes inputs */
#define FC_READ_INPUT_STATUS 0x02 /* discretes outputs */
#define FC_READ_HOLDING_REGISTERS 0x03
#define FC_READ_INPUT_REGISTERS 0x04
#define FC_FORCE_SINGLE_COIL 0x05
#define FC_PRESET_SINGLE_REGISTER 0x06
#define FC_READ_EXCEPTION_STATUS 0x07
#define FC_FORCE_MULTIPLE_COILS 0x0F
#define FC_PRESET_MULTIPLE_REGISTERS 0x10
#define FC_REPORT_SLAVE_ID 0x11
/* Protocol exceptions */
#define ILLEGAL_FUNCTION -0x01
#define ILLEGAL_DATA_ADDRESS -0x02
#define ILLEGAL_DATA_VALUE -0x03
#define SLAVE_DEVICE_FAILURE -0x04
#define SERVER_FAILURE -0x04
#define ACKNOWLEDGE -0x05
#define SLAVE_DEVICE_BUSY -0x06
#define SERVER_BUSY -0x06
#define NEGATIVE_ACKNOWLEDGE -0x07
#define MEMORY_PARITY_ERROR -0x08
#define GATEWAY_PROBLEM_PATH -0x0A
#define GATEWAY_PROBLEM_TARGET -0x0B
/* Local */
#define COMM_TIME_OUT -0x0C
#define PORT_SOCKET_FAILURE -0x0D
#define SELECT_FAILURE -0x0E
#define TOO_MANY_DATA -0x0F
#define INVALID_CRC -0x10
#define INVALID_EXCEPTION_CODE -0x11
#define CONNECTION_CLOSED -0x12
/* Internal using */
#define MSG_LENGTH_UNDEFINED -1
typedef enum { RTU=0, TCP } type_com_t;
typedef enum { FLUSH_OR_RECONNECT_ON_ERROR, NOP_ON_ERROR } error_handling_t;
/* This structure is byte-aligned */
typedef struct {
/* Descriptor (tty or socket) */
int fd;
/* Communication mode: RTU or TCP */
type_com_t type_com;
/* Flag debug */
int debug;
/* TCP port */
int port;
/* Device: "/dev/ttyS0", "/dev/ttyUSB0" or "/dev/tty.USA19*"
on Mac OS X for KeySpan USB<->Serial adapters this string
had to be made bigger on OS X as the directory+file name
was bigger than 19 bytes. Making it 67 bytes for now, but
OS X does support 256 byte file names. May become a problem
in the future. */
#ifdef __APPLE_CC__
char device[64];
#else
char device[16];
#endif
/* Bauds: 9600, 19200, 57600, 115200, etc */
int baud;
/* Data bit */
uint8_t data_bit;
/* Stop bit */
uint8_t stop_bit;
/* Parity: "even", "odd", "none" */
char parity[5];
/* In error_treat with TCP, do a reconnect or just dump the error */
uint8_t error_handling;
/* IP address */
char ip[16];
/* Save old termios settings */
struct termios old_tios;
} modbus_param_t;
typedef struct {
int nb_coil_status;
int nb_input_status;
int nb_input_registers;
int nb_holding_registers;
uint8_t *tab_coil_status;
uint8_t *tab_input_status;
uint16_t *tab_input_registers;
uint16_t *tab_holding_registers;
} modbus_mapping_t;
/* All functions used for sending or receiving data return:
- the numbers of values (bits or word) if success (0 or more)
- less than 0 for exceptions errors
*/
/* Reads the boolean status of coils and sets the array elements in
the destination to TRUE or FALSE */
int read_coil_status(modbus_param_t *mb_param, int slave,
int start_addr, int nb, uint8_t *dest);
/* Same as read_coil_status but reads the slaves input table */
int read_input_status(modbus_param_t *mb_param, int slave,
int start_addr, int nb, uint8_t *dest);
/* Reads the holding registers in a slave and put the data into an
array */
int read_holding_registers(modbus_param_t *mb_param, int slave,
int start_addr, int nb, uint16_t *dest);
/* Reads the input registers in a slave and put the data into an
array */
int read_input_registers(modbus_param_t *mb_param, int slave,
int start_addr, int nb, uint16_t *dest);
/* Turns ON or OFF a single coil in the slave device */
int force_single_coil(modbus_param_t *mb_param, int slave,
int coil_addr, int state);
/* Sets a value in one holding register in the slave device */
int preset_single_register(modbus_param_t *mb_param, int slave,
int reg_addr, int value);
/* Sets/resets the coils in the slave from an array in argument */
int force_multiple_coils(modbus_param_t *mb_param, int slave,
int start_addr, int nb, const uint8_t *data);
/* Copies the values in the slave from the array given in argument */
int preset_multiple_registers(modbus_param_t *mb_param, int slave,
int start_addr, int nb, const uint16_t *data);
/* Returns the slave id! */
int report_slave_id(modbus_param_t *mb_param, int slave, uint8_t *dest);
/* Initializes the modbus_param_t structure for RTU.
- device: "/dev/ttyS0"
- baud: 9600, 19200, 57600, 115200, etc
- parity: "even", "odd" or "none"
- data_bits: 5, 6, 7, 8
- stop_bits: 1, 2
*/
void modbus_init_rtu(modbus_param_t *mb_param, const char *device,
int baud, const char *parity, int data_bit,
int stop_bit);
/* Initializes the modbus_param_t structure for TCP.
- ip : "192.168.0.5"
- port : 1099
Set the port to MODBUS_TCP_DEFAULT_PORT to use the default one
(502). It's convenient to use a port number greater than or equal
to 1024 because it's not necessary to be root to use this port
number.
*/
void modbus_init_tcp(modbus_param_t *mb_param, const char *ip_address, int port);
/* By default, the error handling mode used is RECONNECT_ON_ERROR.
With RECONNECT_ON_ERROR, the library will attempt an immediate
reconnection which may hang for several seconds if the network to
the remote target unit is down.
With NOP_ON_ERROR, it is expected that the application will
check for network error returns and deal with them as necessary.
This function is only useful in TCP mode.
*/
void modbus_set_error_handling(modbus_param_t *mb_param, error_handling_t error_handling);
/* Establishes a modbus connexion.
Returns -1 if an error occured. */
int modbus_connect(modbus_param_t *mb_param);
/* Closes a modbus connection */
void modbus_close(modbus_param_t *mb_param);
/* Activates the debug messages */
void modbus_set_debug(modbus_param_t *mb_param, int boolean);
/**
* SLAVE/CLIENT FUNCTIONS
**/
/* Allocates 4 arrays to store coils, input status, input registers and
holding registers. The pointers are stored in modbus_mapping structure.
Returns: TRUE if ok, FALSE on failure
*/
int modbus_mapping_new(modbus_mapping_t *mb_mapping,
int nb_coil_status, int nb_input_status,
int nb_holding_registers, int nb_input_registers);
/* Frees the 4 arrays */
void modbus_mapping_free(modbus_mapping_t *mb_mapping);
/* Listens for any query from one or many modbus masters in TCP.
Returns: socket
*/
int modbus_slave_listen_tcp(modbus_param_t *mb_param, int nb_connection);
/* Waits for a connection */
int modbus_slave_accept_tcp(modbus_param_t *mb_param, int *socket);
/* Listens for any query from a modbus master in TCP, requires the socket file
descriptor etablished with the master device in argument.
Returns:
- 0 if OK, or a negative error number if the request fails
- query, message received
- query_length, length in bytes of the message
*/
int modbus_slave_receive(modbus_param_t *mb_param, int sockfd,
uint8_t *query, int *query_length);
/* Manages the received query.
Analyses the query and constructs a response.
If an error occurs, this function construct the response
accordingly.
*/
void modbus_manage_query(modbus_param_t *mb_param, const uint8_t *query,
int query_length, modbus_mapping_t *mb_mapping);
/**
* UTILS FUNCTIONS
**/
/* Sets many input/coil status from a single byte value (all 8 bits of
the byte value are setted) */
void set_bits_from_byte(uint8_t *dest, int address, const uint8_t value);
/* Sets many input/coil status from a table of bytes (only the bits
between address and address + nb_bits are setted) */
void set_bits_from_bytes(uint8_t *dest, int address, int nb_bits,
const uint8_t *tab_byte);
/* Gets the byte value from many input/coil status.
To obtain a full byte, set nb_bits to 8. */
uint8_t get_byte_from_bits(const uint8_t *src, int address, int nb_bits);
#ifdef __cplusplus
}
#endif
#endif /* _MODBUS_H_ */