src/modbus-private.h

   1 /*
   2  * Copyright © Stéphane Raimbault <stephane.raimbault@gmail.com>
   3  *
   4  * SPDX-License-Identifier: LGPL-2.1-or-later
   5  */
   6
   7 #ifndef MODBUS_PRIVATE_H
   8 #define MODBUS_PRIVATE_H
   9
  10 // clang-format off
  11 #ifndef _MSC_VER
  12 # include <stdint.h>
  13 # include <sys/time.h>
  14 #else
  15 # include "stdint.h"
  16 # include <time.h>
  17 typedef int ssize_t;
  18 #endif
  19 // clang-format on
  20 #include <config.h>
  21 #include <sys/types.h>
  22
  23 #include "modbus.h"
  24
  25 MODBUS_BEGIN_DECLS
  26
  27 /* It's not really the minimal length (the real one is report slave ID
  28  * in RTU (4 bytes)) but it's a convenient size to use in RTU or TCP
  29  * communications to read many values or write a single one.
  30  * Maximum between :
  31  * - HEADER_LENGTH_TCP (7) + function (1) + address (2) + number (2)
  32  * - HEADER_LENGTH_RTU (1) + function (1) + address (2) + number (2) + CRC (2)
  33  */
  34 #define _MIN_REQ_LENGTH 12
  35
  36 #define _REPORT_SLAVE_ID 180
  37
  38 #define _MODBUS_EXCEPTION_RSP_LENGTH 5
  39
  40 /* Timeouts in microsecond (0.5 s) */
  41 #define _RESPONSE_TIMEOUT 500000
  42 #define _BYTE_TIMEOUT     500000
  43
  44 typedef enum {
  45     _MODBUS_BACKEND_TYPE_RTU = 0,
  46     _MODBUS_BACKEND_TYPE_TCP
  47 } modbus_backend_type_t;
  48
  49 /*
  50  *  ---------- Request     Indication ----------
  51  *  | Client | ---------------------->| Server |
  52  *  ---------- Confirmation  Response ----------
  53  */
  54 typedef enum {
  55     /* Request message on the server side */
  56     MSG_INDICATION,
  57     /* Request message on the client side */
  58     MSG_CONFIRMATION
  59 } msg_type_t;
  60
  61 /* This structure reduces the number of params in functions and so
  62  * optimizes the speed of execution (~ 37%). */
  63 typedef struct _sft {
  64     int slave;
  65     int function;
  66     int t_id;
  67 } sft_t;
  68
  69 typedef struct _modbus_backend {
  70     unsigned int backend_type;
  71     unsigned int header_length;
  72     unsigned int checksum_length;
  73     unsigned int max_adu_length;
  74     int (*set_slave)(modbus_t *ctx, int slave);
  75     int (*build_request_basis)(
  76         modbus_t *ctx, int function, int addr, int nb, uint8_t *req);
  77     int (*build_response_basis)(sft_t *sft, uint8_t *rsp);
  78     int (*prepare_response_tid)(const uint8_t *req, int *req_length);
  79     int (*send_msg_pre)(uint8_t *req, int req_length);
  80     ssize_t (*send)(modbus_t *ctx, const uint8_t *req, int req_length);
  81     int (*receive)(modbus_t *ctx, uint8_t *req);
  82     ssize_t (*recv)(modbus_t *ctx, uint8_t *rsp, int rsp_length);
  83     int (*check_integrity)(modbus_t *ctx, uint8_t *msg, const int msg_length);
  84     int (*pre_check_confirmation)(modbus_t *ctx,
  85                                   const uint8_t *req,
  86                                   const uint8_t *rsp,
  87                                   int rsp_length);
  88     int (*connect)(modbus_t *ctx);
  89     void (*close)(modbus_t *ctx);
  90     int (*flush)(modbus_t *ctx);
  91     int (*select)(modbus_t *ctx, fd_set *rset, struct timeval *tv, int msg_length);
  92     void (*free)(modbus_t *ctx);
  93 } modbus_backend_t;
  94
  95 struct _modbus {
  96     /* Slave address */
  97     int slave;
  98     /* Socket or file descriptor */
  99     int s;
 100     int debug;
 101     int error_recovery;
 102     int quirks;
 103     struct timeval response_timeout;
 104     struct timeval byte_timeout;
 105     struct timeval indication_timeout;
 106     const modbus_backend_t *backend;
 107     void *backend_data;
 108 };
 109
 110 void _modbus_init_common(modbus_t *ctx);
 111 void _error_print(modbus_t *ctx, const char *context);
 112 int _modbus_receive_msg(modbus_t *ctx, uint8_t *msg, msg_type_t msg_type);
 113
 114 #ifndef HAVE_STRLCPY
 115 size_t strlcpy(char *dest, const char *src, size_t dest_size);
 116 #endif
 117
 118 MODBUS_END_DECLS
 119
 120 #endif /* MODBUS_PRIVATE_H */