1 /*

     2  * Copyright (c) 2002,2016 Mario de Sousa (msousa@fe.up.pt)

     3  *

     4  * This file is part of the Modbus library for Beremiz and matiec.

     5  *

     6  * This Modbus library is free software: you can redistribute it and/or modify

     7  * it under the terms of the GNU Lesser General Public License as published by

     8  * the Free Software Foundation, either version 3 of the License, or

     9  * (at your option) any later version.

    10  *

    11  * This program is distributed in the hope that it will be useful, but

    12  * WITHOUT ANY WARRANTY; without even the implied warranty of

    13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser 

    14  * General Public License for more details.

    15  *

    16  * You should have received a copy of the GNU Lesser General Public License

    17  * along with this Modbus library.  If not, see <http://www.gnu.org/licenses/>.

    18  *

    19  * This code is made available on the understanding that it will not be

    20  * used in safety-critical situations without a full and competent review.

    21  */

    22 

    23 

    24 

    25 #ifndef MB_UTIL_H

    26 #define MB_UTIL_H

    27 

    28 /* This file has constants related to the modbus protocol */

    29 /*

    30  * Some of these constants are specific to the layer two protocols

    31  * (i.e. master and slave), while others are specific of the

    32  * layer one protocols (i.e. rtu, ascii, tcp).

    33  *

    34  * a) Unfortunately, due to the nature of the modbus protocol, that does not

    35  * include a frame size field in the layer 1 frame (see note 1), and the

    36  * fact that we are implementing it at the user level, the implementation

    37  * of some layer 1 protocols need to know the content of the layer 2 protocol

    38  * in order to determine the size of the frame.

    39  *

    40  * b) The layer two message formats are in fact the same, just reversing the role

    41  * being played (master or slave).

    42  *

    43  * Bothe a) and b) mean we need the same modbus protocol constants in several files.

    44  * It ends up making more sense to put them all together in a single file, which

    45  * makes updating easier, even though we are trying to strictly seperate the layer 1

    46  * and layer 2 protocols.

    47  *

    48  *

    49  *

    50  * Notes:

    51  *  (1) There is no layer 1 field with the frame size, nevertheless this

    52  *      size can be determined indirectly due to timing restrictions on the rtu

    53  *      protocol. Unfortunately, due to the fact that we are implementing

    54  *      it at the user level, we are not guaranteed to detect these timings

    55  *      correctly, and therefore have to rely on layer 2 protocol info to

    56  *      determine the frame size.

    57  *      For the ascii protocol, the frame size is determined indirectly by

    58  *      a frame header and tail, so we do not use layer 2 protocol info.

    59  */

    60 

    61 

    62  /* Layer 2 Frame Structure...                */

    63  /* Valid for both master and slave protocols */

    64 #define L2_FRAME_HEADER_LENGTH    6

    65 #define L2_FRAME_BYTECOUNT_LENGTH 1

    66 #define L2_FRAME_DATABYTES_LENGTH 255

    67 #define MAX_L2_FRAME_LENGTH (L2_FRAME_HEADER_LENGTH + L2_FRAME_BYTECOUNT_LENGTH +    \

    68                              L2_FRAME_DATABYTES_LENGTH)

    69 

    70 #define L2_FRAME_SLAVEID_OFS    0

    71 #define L2_FRAME_FUNCTION_OFS   1

    72 

    73  /* Layer 1 - Ascii Frame sizes... */

    74 #define L2_TO_ASC_CODING        2 /* number of ascii bytes used to code a Layer 2 frame byte */

    75 #define ASC_FRAME_HEADER_LENGTH 1

    76 #define ASC_FRAME_HEADER        ':'

    77 #define ASC_FRAME_TAIL_LENGTH   2

    78 #define ASC_FRAME_TAIL_0        '\13' /* 'CR' */

    79 #define ASC_FRAME_TAIL_1        '\10' /* 'LF' */

    80 #define ASC_FRAME_LRC_LENGTH    2

    81 

    82  /* Layer 1 - RTU Frame sizes... */

    83 #define RTU_FRAME_CRC_LENGTH    2

    84 

    85  /* Layer 1 - TCP Frame sizes... */

    86 #define TCP_HEADER_LENGTH       6

    87 

    88  /* Global Frame sizes */

    89 #define MAX_RTU_FRAME_LENGTH MAX_L2_FRAME_LENGTH + RTU_FRAME_CRC_LENGTH

    90 #define MAX_ASC_FRAME_LENGTH ((MAX_L2_FRAME_LENGTH * L2_TO_ASC_CODING) +             \

    91                               ASC_FRAME_HEADER_LENGTH + ASC_FRAME_TAIL_LENGTH +      \

    92                               ASC_FRAME_LRC_LENGTH)

    93                               

    94 

    95 /* Modbus Exception codes */

    96 #define ERR_ILLEGAL_FUNCTION                        0x01

    97 #define ERR_ILLEGAL_DATA_ADDRESS                    0x02 

    98 #define ERR_ILLEGAL_DATA_VALUE                      0x03 

    99 #define ERR_SLAVE_DEVICE_FAILURE                    0x04 

   100 #define ERR_ACKNOWLEDGE                             0x05 

   101 #define ERR_SLAVE_DEVICE_BUSY                       0x06 

   102 #define ERR_NEGATIVE_ACKNOWLEDGE                    0x07 

   103 #define ERR_MEMORY_PARITY_ERROR                     0x08 

   104 #define ERR_GATEWAY_PATH_UNAVAILABLE                0x0A 

   105 #define ERR_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND 0x0B 

   106 

   107 

   108 

   109 #endif  /* MB_UTIL_H */

   110 

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