root / freemodbus / modbus / rtu / mbrtu.c @ 20e5429c
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1 | 20e5429c | Tom Mullins | /*
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2 | * FreeModbus Libary: A portable Modbus implementation for Modbus ASCII/RTU.
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3 | * Copyright (c) 2006 Christian Walter <wolti@sil.at>
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4 | * All rights reserved.
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5 | *
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6 | * Redistribution and use in source and binary forms, with or without
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7 | * modification, are permitted provided that the following conditions
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8 | * are met:
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9 | * 1. Redistributions of source code must retain the above copyright
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10 | * notice, this list of conditions and the following disclaimer.
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11 | * 2. Redistributions in binary form must reproduce the above copyright
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12 | * notice, this list of conditions and the following disclaimer in the
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13 | * documentation and/or other materials provided with the distribution.
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14 | * 3. The name of the author may not be used to endorse or promote products
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15 | * derived from this software without specific prior written permission.
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16 | *
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17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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18 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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19 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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20 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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21 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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22 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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23 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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24 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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25 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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26 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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27 | *
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28 | * File: $Id: mbrtu.c,v 1.18 2007/09/12 10:15:56 wolti Exp $
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29 | */
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30 | |||
31 | /* ----------------------- System includes ----------------------------------*/
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32 | #include "stdlib.h" |
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33 | #include "string.h" |
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34 | |||
35 | /* ----------------------- Platform includes --------------------------------*/
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36 | #include "port.h" |
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37 | |||
38 | /* ----------------------- Modbus includes ----------------------------------*/
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39 | #include "mb.h" |
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40 | #include "mbrtu.h" |
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41 | #include "mbframe.h" |
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42 | |||
43 | #include "mbcrc.h" |
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44 | #include "mbport.h" |
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45 | |||
46 | /* ----------------------- Defines ------------------------------------------*/
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47 | #define MB_SER_PDU_SIZE_MIN 4 /*!< Minimum size of a Modbus RTU frame. */ |
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48 | #define MB_SER_PDU_SIZE_MAX 256 /*!< Maximum size of a Modbus RTU frame. */ |
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49 | #define MB_SER_PDU_SIZE_CRC 2 /*!< Size of CRC field in PDU. */ |
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50 | #define MB_SER_PDU_ADDR_OFF 0 /*!< Offset of slave address in Ser-PDU. */ |
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51 | #define MB_SER_PDU_PDU_OFF 1 /*!< Offset of Modbus-PDU in Ser-PDU. */ |
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52 | |||
53 | /* ----------------------- Type definitions ---------------------------------*/
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54 | typedef enum |
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55 | { |
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56 | STATE_RX_INIT, /*!< Receiver is in initial state. */
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57 | STATE_RX_IDLE, /*!< Receiver is in idle state. */
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58 | STATE_RX_RCV, /*!< Frame is beeing received. */
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59 | STATE_RX_ERROR /*!< If the frame is invalid. */
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60 | } eMBRcvState; |
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61 | |||
62 | typedef enum |
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63 | { |
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64 | STATE_TX_IDLE, /*!< Transmitter is in idle state. */
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65 | STATE_TX_XMIT /*!< Transmitter is in transfer state. */
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66 | } eMBSndState; |
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67 | |||
68 | /* ----------------------- Static variables ---------------------------------*/
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69 | static volatile eMBSndState eSndState; |
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70 | static volatile eMBRcvState eRcvState; |
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71 | |||
72 | volatile UCHAR ucRTUBuf[MB_SER_PDU_SIZE_MAX];
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73 | |||
74 | static volatile UCHAR *pucSndBufferCur; |
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75 | static volatile USHORT usSndBufferCount; |
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76 | |||
77 | static volatile USHORT usRcvBufferPos; |
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78 | |||
79 | /* ----------------------- Start implementation -----------------------------*/
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80 | eMBErrorCode |
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81 | eMBRTUInit( UCHAR ucSlaveAddress, UCHAR ucPort, ULONG ulBaudRate, eMBParity eParity ) |
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82 | { |
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83 | eMBErrorCode eStatus = MB_ENOERR; |
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84 | ULONG usTimerT35_50us; |
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85 | |||
86 | ( void )ucSlaveAddress;
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87 | ENTER_CRITICAL_SECTION( ); |
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88 | |||
89 | /* Modbus RTU uses 8 Databits. */
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90 | if( xMBPortSerialInit( ucPort, ulBaudRate, 8, eParity ) != TRUE ) |
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91 | { |
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92 | eStatus = MB_EPORTERR; |
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93 | } |
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94 | else
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95 | { |
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96 | /* If baudrate > 19200 then we should use the fixed timer values
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97 | * t35 = 1750us. Otherwise t35 must be 3.5 times the character time.
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98 | */
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99 | if( ulBaudRate > 19200 ) |
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100 | { |
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101 | usTimerT35_50us = 35; /* 1800us. */ |
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102 | } |
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103 | else
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104 | { |
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105 | /* The timer reload value for a character is given by:
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106 | *
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107 | * ChTimeValue = Ticks_per_1s / ( Baudrate / 11 )
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108 | * = 11 * Ticks_per_1s / Baudrate
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109 | * = 220000 / Baudrate
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110 | * The reload for t3.5 is 1.5 times this value and similary
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111 | * for t3.5.
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112 | */
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113 | usTimerT35_50us = ( 7UL * 220000UL ) / ( 2UL * ulBaudRate ); |
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114 | } |
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115 | if( xMBPortTimersInit( ( USHORT ) usTimerT35_50us ) != TRUE )
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116 | { |
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117 | eStatus = MB_EPORTERR; |
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118 | } |
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119 | } |
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120 | EXIT_CRITICAL_SECTION( ); |
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121 | |||
122 | return eStatus;
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123 | } |
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124 | |||
125 | void
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126 | eMBRTUStart( void )
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127 | { |
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128 | ENTER_CRITICAL_SECTION( ); |
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129 | /* Initially the receiver is in the state STATE_RX_INIT. we start
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130 | * the timer and if no character is received within t3.5 we change
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131 | * to STATE_RX_IDLE. This makes sure that we delay startup of the
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132 | * modbus protocol stack until the bus is free.
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133 | */
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134 | eRcvState = STATE_RX_INIT; |
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135 | vMBPortSerialEnable( TRUE, FALSE ); |
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136 | vMBPortTimersEnable( ); |
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137 | |||
138 | EXIT_CRITICAL_SECTION( ); |
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139 | } |
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140 | |||
141 | void
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142 | eMBRTUStop( void )
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143 | { |
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144 | ENTER_CRITICAL_SECTION( ); |
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145 | vMBPortSerialEnable( FALSE, FALSE ); |
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146 | vMBPortTimersDisable( ); |
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147 | EXIT_CRITICAL_SECTION( ); |
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148 | } |
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149 | |||
150 | eMBErrorCode |
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151 | eMBRTUReceive( UCHAR * pucRcvAddress, UCHAR ** pucFrame, USHORT * pusLength ) |
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152 | { |
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153 | BOOL xFrameReceived = FALSE; |
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154 | eMBErrorCode eStatus = MB_ENOERR; |
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155 | |||
156 | ENTER_CRITICAL_SECTION( ); |
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157 | assert( usRcvBufferPos < MB_SER_PDU_SIZE_MAX ); |
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158 | |||
159 | /* Length and CRC check */
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160 | if( ( usRcvBufferPos >= MB_SER_PDU_SIZE_MIN )
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161 | && ( usMBCRC16( ( UCHAR * ) ucRTUBuf, usRcvBufferPos ) == 0 ) )
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162 | { |
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163 | /* Save the address field. All frames are passed to the upper layed
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164 | * and the decision if a frame is used is done there.
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165 | */
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166 | *pucRcvAddress = ucRTUBuf[MB_SER_PDU_ADDR_OFF]; |
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167 | |||
168 | /* Total length of Modbus-PDU is Modbus-Serial-Line-PDU minus
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169 | * size of address field and CRC checksum.
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170 | */
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171 | *pusLength = ( USHORT )( usRcvBufferPos - MB_SER_PDU_PDU_OFF - MB_SER_PDU_SIZE_CRC ); |
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172 | |||
173 | /* Return the start of the Modbus PDU to the caller. */
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174 | *pucFrame = ( UCHAR * ) & ucRTUBuf[MB_SER_PDU_PDU_OFF]; |
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175 | xFrameReceived = TRUE; |
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176 | } |
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177 | else
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178 | { |
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179 | eStatus = MB_EIO; |
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180 | } |
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181 | |||
182 | EXIT_CRITICAL_SECTION( ); |
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183 | return eStatus;
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184 | } |
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185 | |||
186 | eMBErrorCode |
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187 | eMBRTUSend( UCHAR ucSlaveAddress, const UCHAR * pucFrame, USHORT usLength )
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188 | { |
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189 | eMBErrorCode eStatus = MB_ENOERR; |
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190 | USHORT usCRC16; |
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191 | |||
192 | ENTER_CRITICAL_SECTION( ); |
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193 | |||
194 | /* Check if the receiver is still in idle state. If not we where to
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195 | * slow with processing the received frame and the master sent another
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196 | * frame on the network. We have to abort sending the frame.
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197 | */
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198 | if( eRcvState == STATE_RX_IDLE )
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199 | { |
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200 | /* First byte before the Modbus-PDU is the slave address. */
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201 | pucSndBufferCur = ( UCHAR * ) pucFrame - 1;
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202 | usSndBufferCount = 1;
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203 | |||
204 | /* Now copy the Modbus-PDU into the Modbus-Serial-Line-PDU. */
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205 | pucSndBufferCur[MB_SER_PDU_ADDR_OFF] = ucSlaveAddress; |
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206 | usSndBufferCount += usLength; |
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207 | |||
208 | /* Calculate CRC16 checksum for Modbus-Serial-Line-PDU. */
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209 | usCRC16 = usMBCRC16( ( UCHAR * ) pucSndBufferCur, usSndBufferCount ); |
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210 | ucRTUBuf[usSndBufferCount++] = ( UCHAR )( usCRC16 & 0xFF );
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211 | ucRTUBuf[usSndBufferCount++] = ( UCHAR )( usCRC16 >> 8 );
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212 | |||
213 | /* Activate the transmitter. */
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214 | eSndState = STATE_TX_XMIT; |
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215 | vMBPortSerialEnable( FALSE, TRUE ); |
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216 | } |
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217 | else
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218 | { |
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219 | eStatus = MB_EIO; |
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220 | } |
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221 | EXIT_CRITICAL_SECTION( ); |
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222 | return eStatus;
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223 | } |
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224 | |||
225 | BOOL |
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226 | xMBRTUReceiveFSM( void )
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227 | { |
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228 | BOOL xTaskNeedSwitch = FALSE; |
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229 | UCHAR ucByte; |
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230 | |||
231 | assert( eSndState == STATE_TX_IDLE ); |
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232 | |||
233 | /* Always read the character. */
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234 | ( void )xMBPortSerialGetByte( ( CHAR * ) & ucByte );
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235 | |||
236 | switch ( eRcvState )
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237 | { |
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238 | /* If we have received a character in the init state we have to
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239 | * wait until the frame is finished.
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240 | */
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241 | case STATE_RX_INIT:
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242 | vMBPortTimersEnable( ); |
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243 | break;
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244 | |||
245 | /* In the error state we wait until all characters in the
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246 | * damaged frame are transmitted.
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247 | */
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248 | case STATE_RX_ERROR:
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249 | vMBPortTimersEnable( ); |
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250 | break;
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251 | |||
252 | /* In the idle state we wait for a new character. If a character
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253 | * is received the t1.5 and t3.5 timers are started and the
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254 | * receiver is in the state STATE_RX_RECEIVCE.
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255 | */
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256 | case STATE_RX_IDLE:
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257 | usRcvBufferPos = 0;
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258 | ucRTUBuf[usRcvBufferPos++] = ucByte; |
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259 | eRcvState = STATE_RX_RCV; |
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260 | |||
261 | /* Enable t3.5 timers. */
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262 | vMBPortTimersEnable( ); |
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263 | break;
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264 | |||
265 | /* We are currently receiving a frame. Reset the timer after
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266 | * every character received. If more than the maximum possible
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267 | * number of bytes in a modbus frame is received the frame is
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268 | * ignored.
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269 | */
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270 | case STATE_RX_RCV:
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271 | if( usRcvBufferPos < MB_SER_PDU_SIZE_MAX )
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272 | { |
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273 | ucRTUBuf[usRcvBufferPos++] = ucByte; |
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274 | } |
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275 | else
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276 | { |
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277 | eRcvState = STATE_RX_ERROR; |
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278 | } |
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279 | vMBPortTimersEnable( ); |
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280 | break;
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281 | } |
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282 | return xTaskNeedSwitch;
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283 | } |
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284 | |||
285 | BOOL |
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286 | xMBRTUTransmitFSM( void )
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287 | { |
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288 | BOOL xNeedPoll = FALSE; |
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289 | |||
290 | assert( eRcvState == STATE_RX_IDLE ); |
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291 | |||
292 | switch ( eSndState )
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293 | { |
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294 | /* We should not get a transmitter event if the transmitter is in
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295 | * idle state. */
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296 | case STATE_TX_IDLE:
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297 | /* enable receiver/disable transmitter. */
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298 | vMBPortSerialEnable( TRUE, FALSE ); |
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299 | break;
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300 | |||
301 | case STATE_TX_XMIT:
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302 | /* check if we are finished. */
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303 | if( usSndBufferCount != 0 ) |
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304 | { |
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305 | xMBPortSerialPutByte( ( CHAR )*pucSndBufferCur ); |
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306 | pucSndBufferCur++; /* next byte in sendbuffer. */
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307 | usSndBufferCount--; |
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308 | } |
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309 | else
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310 | { |
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311 | xNeedPoll = xMBPortEventPost( EV_FRAME_SENT ); |
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312 | /* Disable transmitter. This prevents another transmit buffer
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313 | * empty interrupt. */
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314 | vMBPortSerialEnable( TRUE, FALSE ); |
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315 | eSndState = STATE_TX_IDLE; |
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316 | } |
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317 | break;
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318 | } |
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319 | |||
320 | return xNeedPoll;
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321 | } |
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322 | |||
323 | BOOL |
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324 | xMBRTUTimerT35Expired( void )
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325 | { |
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326 | BOOL xNeedPoll = FALSE; |
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327 | |||
328 | switch ( eRcvState )
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329 | { |
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330 | /* Timer t35 expired. Startup phase is finished. */
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331 | case STATE_RX_INIT:
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332 | xNeedPoll = xMBPortEventPost( EV_READY ); |
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333 | break;
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334 | |||
335 | /* A frame was received and t35 expired. Notify the listener that
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336 | * a new frame was received. */
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337 | case STATE_RX_RCV:
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338 | xNeedPoll = xMBPortEventPost( EV_FRAME_RECEIVED ); |
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339 | break;
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340 | |||
341 | /* An error occured while receiving the frame. */
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342 | case STATE_RX_ERROR:
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343 | break;
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344 | |||
345 | /* Function called in an illegal state. */
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346 | default:
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347 | assert( ( eRcvState == STATE_RX_INIT ) || |
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348 | ( eRcvState == STATE_RX_RCV ) || ( eRcvState == STATE_RX_ERROR ) ); |
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349 | } |
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350 | |||
351 | vMBPortTimersDisable( ); |
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352 | eRcvState = STATE_RX_IDLE; |
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353 | |||
354 | return xNeedPoll;
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355 | } |