361 lines
11 KiB
C
361 lines
11 KiB
C
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/*
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* FreeModbus Libary: A portable Modbus implementation for Modbus ASCII/RTU.
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* Copyright (c) 2006 Christian Walter <wolti@sil.at>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* File: $Id: mbrtu.c,v 1.18 2007/09/12 10:15:56 wolti Exp $
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*/
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/* ----------------------- System includes ----------------------------------*/
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#include "stdlib.h"
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#include "string.h"
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/* ----------------------- Platform includes --------------------------------*/
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#include "port.h"
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/* ----------------------- Modbus includes ----------------------------------*/
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#include "mb.h"
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#include "mbrtu.h"
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#include "mbframe.h"
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#include "mbcrc.h"
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#include "mbport.h"
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/* ----------------------- Defines ------------------------------------------*/
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#define MB_SER_PDU_SIZE_MIN 4 /*!< Minimum size of a Modbus RTU frame. */
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#define MB_SER_PDU_SIZE_MAX 256 /*!< Maximum size of a Modbus RTU frame. */
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#define MB_SER_PDU_SIZE_CRC 2 /*!< Size of CRC field in PDU. */
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#define MB_SER_PDU_ADDR_OFF 0 /*!< Offset of slave address in Ser-PDU. */
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#define MB_SER_PDU_PDU_OFF 1 /*!< Offset of Modbus-PDU in Ser-PDU. */
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/* ----------------------- Type definitions ---------------------------------*/
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typedef enum
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{
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STATE_RX_INIT, /*!< Receiver is in initial state. */
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STATE_RX_IDLE, /*!< Receiver is in idle state. */
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STATE_RX_RCV, /*!< Frame is beeing received. */
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STATE_RX_ERROR /*!< If the frame is invalid. */
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} eMBRcvState;
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typedef enum
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{
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STATE_TX_IDLE, /*!< Transmitter is in idle state. */
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STATE_TX_XMIT /*!< Transmitter is in transfer state. */
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} eMBSndState;
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/* ----------------------- Static variables ---------------------------------*/
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static volatile eMBSndState eSndState;
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static volatile eMBRcvState eRcvState;
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volatile UCHAR ucRTUBuf[MB_SER_PDU_SIZE_MAX];
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static volatile UCHAR *pucSndBufferCur;
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static volatile USHORT usSndBufferCount;
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static volatile USHORT usRcvBufferPos;
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/* ----------------------- Start implementation -----------------------------*/
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eMBErrorCode
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eMBRTUInit( UCHAR ucSlaveAddress, UCHAR ucPort, ULONG ulBaudRate, eMBParity eParity )
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{
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eMBErrorCode eStatus = MB_ENOERR;
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ULONG usTimerT35_50us;
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( void )ucSlaveAddress;
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ENTER_CRITICAL_SECTION( );
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/* Modbus RTU uses 8 Databits. */
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if( xMBPortSerialInit( ucPort, ulBaudRate, 8, eParity ) != TRUE )
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{
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eStatus = MB_EPORTERR;
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}
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else
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{
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/* If baudrate > 19200 then we should use the fixed timer values
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* t35 = 1750us. Otherwise t35 must be 3.5 times the character time.
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*/
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if( ulBaudRate > 19200 )
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{
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usTimerT35_50us = 35; /* 1800us. */
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}
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else
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{
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/* The timer reload value for a character is given by:
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*
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* ChTimeValue = Ticks_per_1s / ( Baudrate / 11 )
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* = 11 * Ticks_per_1s / Baudrate
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* = 220000 / Baudrate
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* The reload for t3.5 is 1.5 times this value and similary
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* for t3.5.
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*/
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usTimerT35_50us = ( 7UL * 220000UL ) / ( 2UL * ulBaudRate );
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}
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if( xMBPortTimersInit( ( USHORT ) usTimerT35_50us ) != TRUE )
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{
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eStatus = MB_EPORTERR;
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}
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}
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EXIT_CRITICAL_SECTION( );
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return eStatus;
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}
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void
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eMBRTUStart( void )
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{
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ENTER_CRITICAL_SECTION( );
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/* Initially the receiver is in the state STATE_RX_INIT. we start
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* the timer and if no character is received within t3.5 we change
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* to STATE_RX_IDLE. This makes sure that we delay startup of the
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* modbus protocol stack until the bus is free.
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*/
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eRcvState = STATE_RX_INIT;
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vMBPortSerialEnable( TRUE, FALSE );
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vMBPortTimersEnable( );
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EXIT_CRITICAL_SECTION( );
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}
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void
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eMBRTUStop( void )
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{
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ENTER_CRITICAL_SECTION( );
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vMBPortSerialEnable( FALSE, FALSE );
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vMBPortTimersDisable( );
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EXIT_CRITICAL_SECTION( );
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}
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// The lines below are required to suppress GCC warnings about unused but set variable 'xFrameReceived'
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// This warning is treated as error during compilation.
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#pragma GCC diagnostic push // required for GCC
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#pragma GCC diagnostic ignored "-Wunused-but-set-variable"
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eMBErrorCode
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eMBRTUReceive( UCHAR * pucRcvAddress, UCHAR ** pucFrame, USHORT * pusLength )
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{
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BOOL xFrameReceived = FALSE;
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eMBErrorCode eStatus = MB_ENOERR;
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ENTER_CRITICAL_SECTION( );
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assert( usRcvBufferPos < MB_SER_PDU_SIZE_MAX );
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/* Length and CRC check */
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if( ( usRcvBufferPos >= MB_SER_PDU_SIZE_MIN )
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&& ( usMBCRC16( ( UCHAR * ) ucRTUBuf, usRcvBufferPos ) == 0 ) )
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{
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/* Save the address field. All frames are passed to the upper layed
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* and the decision if a frame is used is done there.
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*/
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*pucRcvAddress = ucRTUBuf[MB_SER_PDU_ADDR_OFF];
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/* Total length of Modbus-PDU is Modbus-Serial-Line-PDU minus
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* size of address field and CRC checksum.
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*/
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*pusLength = ( USHORT )( usRcvBufferPos - MB_SER_PDU_PDU_OFF - MB_SER_PDU_SIZE_CRC );
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/* Return the start of the Modbus PDU to the caller. */
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*pucFrame = ( UCHAR * ) & ucRTUBuf[MB_SER_PDU_PDU_OFF];
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xFrameReceived = TRUE;
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}
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else
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{
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eStatus = MB_EIO;
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}
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EXIT_CRITICAL_SECTION( );
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return eStatus;
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}
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#pragma GCC diagnostic pop // require GCC
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eMBErrorCode
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eMBRTUSend( UCHAR ucSlaveAddress, const UCHAR * pucFrame, USHORT usLength )
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{
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eMBErrorCode eStatus = MB_ENOERR;
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USHORT usCRC16;
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ENTER_CRITICAL_SECTION( );
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/* Check if the receiver is still in idle state. If not we where to
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* slow with processing the received frame and the master sent another
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* frame on the network. We have to abort sending the frame.
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*/
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if( eRcvState == STATE_RX_IDLE )
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{
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/* First byte before the Modbus-PDU is the slave address. */
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pucSndBufferCur = ( UCHAR * ) pucFrame - 1;
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usSndBufferCount = 1;
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/* Now copy the Modbus-PDU into the Modbus-Serial-Line-PDU. */
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pucSndBufferCur[MB_SER_PDU_ADDR_OFF] = ucSlaveAddress;
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usSndBufferCount += usLength;
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/* Calculate CRC16 checksum for Modbus-Serial-Line-PDU. */
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usCRC16 = usMBCRC16( ( UCHAR * ) pucSndBufferCur, usSndBufferCount );
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ucRTUBuf[usSndBufferCount++] = ( UCHAR )( usCRC16 & 0xFF );
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ucRTUBuf[usSndBufferCount++] = ( UCHAR )( usCRC16 >> 8 );
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/* Activate the transmitter. */
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eSndState = STATE_TX_XMIT;
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vMBPortSerialEnable( FALSE, TRUE );
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}
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else
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{
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eStatus = MB_EIO;
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}
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EXIT_CRITICAL_SECTION( );
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return eStatus;
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}
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BOOL
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xMBRTUReceiveFSM( void )
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{
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BOOL xTaskNeedSwitch = FALSE;
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UCHAR ucByte;
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assert( eSndState == STATE_TX_IDLE );
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/* Always read the character. */
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( void )xMBPortSerialGetByte( ( CHAR * ) & ucByte );
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switch ( eRcvState )
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{
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/* If we have received a character in the init state we have to
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* wait until the frame is finished.
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*/
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case STATE_RX_INIT:
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vMBPortTimersEnable( );
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break;
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/* In the error state we wait until all characters in the
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* damaged frame are transmitted.
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*/
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case STATE_RX_ERROR:
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vMBPortTimersEnable( );
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break;
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/* In the idle state we wait for a new character. If a character
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* is received the t1.5 and t3.5 timers are started and the
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* receiver is in the state STATE_RX_RECEIVCE.
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*/
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case STATE_RX_IDLE:
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usRcvBufferPos = 0;
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ucRTUBuf[usRcvBufferPos++] = ucByte;
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eRcvState = STATE_RX_RCV;
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/* Enable t3.5 timers. */
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vMBPortTimersEnable( );
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break;
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/* We are currently receiving a frame. Reset the timer after
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* every character received. If more than the maximum possible
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* number of bytes in a modbus frame is received the frame is
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* ignored.
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*/
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case STATE_RX_RCV:
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if( usRcvBufferPos < MB_SER_PDU_SIZE_MAX )
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{
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ucRTUBuf[usRcvBufferPos++] = ucByte;
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}
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else
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{
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eRcvState = STATE_RX_ERROR;
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}
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vMBPortTimersEnable( );
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break;
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}
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return xTaskNeedSwitch;
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}
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BOOL
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xMBRTUTransmitFSM( void )
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{
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BOOL xNeedPoll = FALSE;
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assert( eRcvState == STATE_RX_IDLE );
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switch ( eSndState )
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{
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/* We should not get a transmitter event if the transmitter is in
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* idle state. */
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case STATE_TX_IDLE:
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/* enable receiver/disable transmitter. */
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vMBPortSerialEnable( TRUE, FALSE );
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break;
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case STATE_TX_XMIT:
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/* check if we are finished. */
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if( usSndBufferCount != 0 )
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{
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xMBPortSerialPutByte( ( CHAR )*pucSndBufferCur );
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pucSndBufferCur++; /* next byte in sendbuffer. */
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usSndBufferCount--;
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}
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else
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{
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xNeedPoll = xMBPortEventPost( EV_FRAME_SENT );
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/* Disable transmitter. This prevents another transmit buffer
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* empty interrupt. */
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vMBPortSerialEnable( TRUE, FALSE );
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eSndState = STATE_TX_IDLE;
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}
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break;
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}
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return xNeedPoll;
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}
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BOOL
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xMBRTUTimerT35Expired( void )
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{
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BOOL xNeedPoll = FALSE;
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switch ( eRcvState )
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{
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/* Timer t35 expired. Startup phase is finished. */
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case STATE_RX_INIT:
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xNeedPoll = xMBPortEventPost( EV_READY );
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break;
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/* A frame was received and t35 expired. Notify the listener that
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* a new frame was received. */
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case STATE_RX_RCV:
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xNeedPoll = xMBPortEventPost( EV_FRAME_RECEIVED );
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break;
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/* An error occured while receiving the frame. */
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case STATE_RX_ERROR:
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break;
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/* Function called in an illegal state. */
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default:
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assert( ( eRcvState == STATE_RX_INIT ) ||
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( eRcvState == STATE_RX_RCV ) || ( eRcvState == STATE_RX_ERROR ) );
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}
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vMBPortTimersDisable( );
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eRcvState = STATE_RX_IDLE;
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return xNeedPoll;
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}
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