root / freemodbus / modbus / functions / mbfuncdisc.c @ 20e5429c
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1 | 20e5429c | Tom Mullins | /*
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2 | * FreeRTOS Modbus Libary: A Modbus serial implementation for FreeRTOS
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3 | * Copyright (C) 2006 Christian Walter <wolti@sil.at>
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4 | *
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5 | * This library is free software; you can redistribute it and/or
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6 | * modify it under the terms of the GNU Lesser General Public
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7 | * License as published by the Free Software Foundation; either
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8 | * version 2.1 of the License, or (at your option) any later version.
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9 | *
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10 | * This library is distributed in the hope that it will be useful,
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11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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13 | * Lesser General Public License for more details.
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14 | *
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15 | * You should have received a copy of the GNU Lesser General Public
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16 | * License along with this library; if not, write to the Free Software
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17 | * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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18 | */
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19 | |||
20 | |||
21 | |||
22 | /* ----------------------- System includes ----------------------------------*/
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23 | #include "stdlib.h" |
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24 | #include "string.h" |
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25 | |||
26 | /* ----------------------- Platform includes --------------------------------*/
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27 | #include "port.h" |
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28 | |||
29 | /* ----------------------- Modbus includes ----------------------------------*/
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30 | #include "mb.h" |
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31 | #include "mbframe.h" |
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32 | #include "mbproto.h" |
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33 | #include "mbconfig.h" |
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34 | |||
35 | /* ----------------------- Defines ------------------------------------------*/
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36 | #define MB_PDU_FUNC_READ_ADDR_OFF ( MB_PDU_DATA_OFF )
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37 | #define MB_PDU_FUNC_READ_DISCCNT_OFF ( MB_PDU_DATA_OFF + 2 ) |
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38 | #define MB_PDU_FUNC_READ_SIZE ( 4 ) |
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39 | #define MB_PDU_FUNC_READ_DISCCNT_MAX ( 0x07D0 ) |
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40 | |||
41 | /* ----------------------- Static functions ---------------------------------*/
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42 | eMBException prveMBError2Exception( eMBErrorCode eErrorCode ); |
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43 | |||
44 | /* ----------------------- Start implementation -----------------------------*/
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45 | |||
46 | #if MB_FUNC_READ_COILS_ENABLED > 0 |
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47 | |||
48 | eMBException |
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49 | eMBFuncReadDiscreteInputs( UCHAR * pucFrame, USHORT * usLen ) |
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50 | { |
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51 | USHORT usRegAddress; |
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52 | USHORT usDiscreteCnt; |
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53 | UCHAR ucNBytes; |
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54 | UCHAR *pucFrameCur; |
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55 | |||
56 | eMBException eStatus = MB_EX_NONE; |
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57 | eMBErrorCode eRegStatus; |
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58 | |||
59 | if( *usLen == ( MB_PDU_FUNC_READ_SIZE + MB_PDU_SIZE_MIN ) )
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60 | { |
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61 | usRegAddress = ( USHORT )( pucFrame[MB_PDU_FUNC_READ_ADDR_OFF] << 8 );
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62 | usRegAddress |= ( USHORT )( pucFrame[MB_PDU_FUNC_READ_ADDR_OFF + 1] );
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63 | usRegAddress++; |
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64 | |||
65 | usDiscreteCnt = ( USHORT )( pucFrame[MB_PDU_FUNC_READ_DISCCNT_OFF] << 8 );
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66 | usDiscreteCnt |= ( USHORT )( pucFrame[MB_PDU_FUNC_READ_DISCCNT_OFF + 1] );
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67 | |||
68 | /* Check if the number of registers to read is valid. If not
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69 | * return Modbus illegal data value exception.
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70 | */
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71 | if( ( usDiscreteCnt >= 1 ) && |
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72 | ( usDiscreteCnt < MB_PDU_FUNC_READ_DISCCNT_MAX ) ) |
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73 | { |
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74 | /* Set the current PDU data pointer to the beginning. */
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75 | pucFrameCur = &pucFrame[MB_PDU_FUNC_OFF]; |
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76 | *usLen = MB_PDU_FUNC_OFF; |
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77 | |||
78 | /* First byte contains the function code. */
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79 | *pucFrameCur++ = MB_FUNC_READ_DISCRETE_INPUTS; |
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80 | *usLen += 1;
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81 | |||
82 | /* Test if the quantity of coils is a multiple of 8. If not last
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83 | * byte is only partially field with unused coils set to zero. */
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84 | if( ( usDiscreteCnt & 0x0007 ) != 0 ) |
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85 | { |
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86 | ucNBytes = ( UCHAR ) ( usDiscreteCnt / 8 + 1 ); |
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87 | } |
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88 | else
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89 | { |
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90 | ucNBytes = ( UCHAR ) ( usDiscreteCnt / 8 );
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91 | } |
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92 | *pucFrameCur++ = ucNBytes; |
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93 | *usLen += 1;
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94 | |||
95 | eRegStatus = |
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96 | eMBRegDiscreteCB( pucFrameCur, usRegAddress, usDiscreteCnt ); |
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97 | |||
98 | /* If an error occured convert it into a Modbus exception. */
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99 | if( eRegStatus != MB_ENOERR )
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100 | { |
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101 | eStatus = prveMBError2Exception( eRegStatus ); |
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102 | } |
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103 | else
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104 | { |
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105 | /* The response contains the function code, the starting address
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106 | * and the quantity of registers. We reuse the old values in the
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107 | * buffer because they are still valid. */
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108 | *usLen += ucNBytes;; |
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109 | } |
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110 | } |
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111 | else
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112 | { |
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113 | eStatus = MB_EX_ILLEGAL_DATA_VALUE; |
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114 | } |
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115 | } |
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116 | else
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117 | { |
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118 | /* Can't be a valid read coil register request because the length
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119 | * is incorrect. */
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120 | eStatus = MB_EX_ILLEGAL_DATA_VALUE; |
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121 | } |
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122 | return eStatus;
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123 | } |
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124 | |||
125 | #endif
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