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/*

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

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 *

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

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 *

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

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

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

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 * (at your option) any later version.

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 *

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

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 * WITHOUT ANY WARRANTY; without even the implied warranty of

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

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 * General Public License for more details.

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 *

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

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

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 *

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

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

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 */

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#ifndef MB_UTIL_H

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#define MB_UTIL_H

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

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/*

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

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

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

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 *

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

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

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

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

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 * in order to determine the size of the frame.

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 *

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

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 * being played (master or slave).

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 *

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

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

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

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 * and layer 2 protocols.

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 *

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 *

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 *

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 * Notes:

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

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

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

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

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

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 *      determine the frame size.

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

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

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 */

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 /* Layer 2 Frame Structure...                */

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 /* Valid for both master and slave protocols */

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#define L2_FRAME_HEADER_LENGTH    6

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#define L2_FRAME_BYTECOUNT_LENGTH 1

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#define L2_FRAME_DATABYTES_LENGTH 255

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#define MAX_L2_FRAME_LENGTH (L2_FRAME_HEADER_LENGTH + L2_FRAME_BYTECOUNT_LENGTH +    \

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                             L2_FRAME_DATABYTES_LENGTH)

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#define L2_FRAME_SLAVEID_OFS    0

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#define L2_FRAME_FUNCTION_OFS   1

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

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

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#define ASC_FRAME_HEADER_LENGTH 1

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#define ASC_FRAME_HEADER        ':'

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#define ASC_FRAME_TAIL_LENGTH   2

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

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

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#define ASC_FRAME_LRC_LENGTH    2

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

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#define RTU_FRAME_CRC_LENGTH    2

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

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#define TCP_HEADER_LENGTH       6

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 /* Global Frame sizes */

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#define MAX_RTU_FRAME_LENGTH (MAX_L2_FRAME_LENGTH + RTU_FRAME_CRC_LENGTH)

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#define MAX_ASC_FRAME_LENGTH ((MAX_L2_FRAME_LENGTH * L2_TO_ASC_CODING) +             \

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                              ASC_FRAME_HEADER_LENGTH + ASC_FRAME_TAIL_LENGTH +      \

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                              ASC_FRAME_LRC_LENGTH)

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/* Modbus Exception codes */

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#define ERR_ILLEGAL_FUNCTION                        0x01

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#define ERR_ILLEGAL_DATA_ADDRESS                    0x02 

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#define ERR_ILLEGAL_DATA_VALUE                      0x03 

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#define ERR_SLAVE_DEVICE_FAILURE                    0x04 

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#define ERR_ACKNOWLEDGE                             0x05 

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#define ERR_SLAVE_DEVICE_BUSY                       0x06 

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#define ERR_NEGATIVE_ACKNOWLEDGE                    0x07 

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#define ERR_MEMORY_PARITY_ERROR                     0x08 

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#define ERR_GATEWAY_PATH_UNAVAILABLE                0x0A 

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#define ERR_GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND 0x0B 

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#endif  /* MB_UTIL_H */

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