mbascii.c

modbus开发程序包

/* 
 * FreeModbus Libary: A portable Modbus implementation for Modbus ASCII/RTU.
 * Copyright (c) 2006 Christian Walter <[e-mail]>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * File: $Id: mbascii.c,v 1.15 2007/02/18 23:46:48 wolti Exp $
 */

/* ----------------------- System includes ----------------------------------*/
#include "stdlib.h"
#include "string.h"

/* ----------------------- Platform includes --------------------------------*/
#include "port.h"

/* ----------------------- Modbus includes ----------------------------------*/
#include "mb.h"
#include "mbconfig.h"
#include "mbascii.h"
#include "mbframe.h"

#include "mbcrc.h"
#include "mbport.h"

#if MB_ASCII_ENABLED > 0

/* ----------------------- Defines ------------------------------------------*/
#define MB_ASCII_DEFAULT_CR     '\r'    /*!< Default CR character for Modbus ASCII. */
#define MB_ASCII_DEFAULT_LF     '\n'    /*!< Default LF character for Modbus ASCII. */
#define MB_SER_PDU_SIZE_MIN     3       /*!< Minimum size of a Modbus ASCII frame. */
#define MB_SER_PDU_SIZE_MAX     256     /*!< Maximum size of a Modbus ASCII frame. */
#define MB_SER_PDU_SIZE_LRC     1       /*!< Size of LRC field in PDU. */
#define MB_SER_PDU_ADDR_OFF     0       /*!< Offset of slave address in Ser-PDU. */
#define MB_SER_PDU_PDU_OFF      1       /*!< Offset of Modbus-PDU in Ser-PDU. */

/* ----------------------- Type definitions ---------------------------------*/
typedef enum
{
    STATE_RX_IDLE,              /*!< Receiver is in idle state. */
    STATE_RX_RCV,               /*!< Frame is beeing received. */
    STATE_RX_WAIT_EOF           /*!< Wait for End of Frame. */
} eMBRcvState;

typedef enum
{
    STATE_TX_IDLE,              /*!< Transmitter is in idle state. */
    STATE_TX_START,             /*!< Starting transmission (':' sent). */
    STATE_TX_DATA,              /*!< Sending of data (Address, Data, LRC). */
    STATE_TX_END,               /*!< End of transmission. */
    STATE_TX_NOTIFY             /*!< Notify sender that the frame has been sent. */
} eMBSndState;

typedef enum
{
    BYTE_HIGH_NIBBLE,           /*!< Character for high nibble of byte. */
    BYTE_LOW_NIBBLE             /*!< Character for low nibble of byte. */
} eMBBytePos;

/* ----------------------- Static functions ---------------------------------*/
static UCHAR    prvucMBCHAR2BIN( UCHAR ucCharacter );

static UCHAR    prvucMBBIN2CHAR( UCHAR ucByte );

static UCHAR    prvucMBLRC( UCHAR * pucFrame, USHORT usLen );

/* ----------------------- Static variables ---------------------------------*/
static volatile eMBSndState eSndState;
static volatile eMBRcvState eRcvState;

/* We reuse the Modbus RTU buffer because only one buffer is needed and the
 * RTU buffer is bigger. */
extern volatile UCHAR ucRTUBuf[];
static volatile UCHAR *ucASCIIBuf = ucRTUBuf;

static volatile USHORT usRcvBufferPos;
static volatile eMBBytePos eBytePos;

static volatile UCHAR *pucSndBufferCur;
static volatile USHORT usSndBufferCount;

static volatile UCHAR ucLRC;
static volatile UCHAR ucMBLFCharacter;

/* ----------------------- Start implementation -----------------------------*/
eMBErrorCode
eMBASCIIInit( UCHAR ucSlaveAddress, UCHAR ucPort, ULONG ulBaudRate, eMBParity eParity )
{
    eMBErrorCode    eStatus = MB_ENOERR;
    ( void )ucSlaveAddress;
    
    ENTER_CRITICAL_SECTION(  );
    ucMBLFCharacter = MB_ASCII_DEFAULT_LF;

    if( xMBPortSerialInit( ucPort, ulBaudRate, 7, eParity ) != TRUE )
    {
        eStatus = MB_EPORTERR;
    }
    else if( xMBPortTimersInit( MB_ASCII_TIMEOUT_SEC * 20000UL ) != TRUE )
    {
        eStatus = MB_EPORTERR;
    }

    EXIT_CRITICAL_SECTION(  );

    return eStatus;
}

void
eMBASCIIStart( void )
{
    ENTER_CRITICAL_SECTION(  );
    vMBPortSerialEnable( TRUE, FALSE );
    eRcvState = STATE_RX_IDLE;
    EXIT_CRITICAL_SECTION(  );

    /* No special startup required for ASCII. */
    ( void )xMBPortEventPost( EV_READY );
}

void
eMBASCIIStop( void )
{
    ENTER_CRITICAL_SECTION(  );
    vMBPortSerialEnable( FALSE, FALSE );
    vMBPortTimersDisable(  );
    EXIT_CRITICAL_SECTION(  );
}

eMBErrorCode
eMBASCIIReceive( UCHAR * pucRcvAddress, UCHAR ** pucFrame, USHORT * pusLength )
{
    eMBErrorCode    eStatus = MB_ENOERR;

    ENTER_CRITICAL_SECTION(  );
    assert( usRcvBufferPos < MB_SER_PDU_SIZE_MAX );

    /* Length and CRC check */
    if( ( usRcvBufferPos >= MB_SER_PDU_SIZE_MIN )
        && ( prvucMBLRC( ( UCHAR * ) ucASCIIBuf, usRcvBufferPos ) == 0 ) )
    {
        /* Save the address field. All frames are passed to the upper layed
         * and the decision if a frame is used is done there.
         */
        *pucRcvAddress = ucASCIIBuf[MB_SER_PDU_ADDR_OFF];

        /* Total length of Modbus-PDU is Modbus-Serial-Line-PDU minus
         * size of address field and CRC checksum.
         */
        *pusLength = ( USHORT )( usRcvBufferPos - MB_SER_PDU_PDU_OFF - MB_SER_PDU_SIZE_LRC );

        /* Return the start of the Modbus PDU to the caller. */
        *pucFrame = ( UCHAR * ) & ucASCIIBuf[MB_SER_PDU_PDU_OFF];
    }
    else
    {
        eStatus = MB_EIO;
    }
    EXIT_CRITICAL_SECTION(  );
    return eStatus;
}

eMBErrorCode
eMBASCIISend( UCHAR ucSlaveAddress, const UCHAR * pucFrame, USHORT usLength )
{
    eMBErrorCode    eStatus = MB_ENOERR;
    UCHAR           usLRC;

    ENTER_CRITICAL_SECTION(  );
    /* Check if the receiver is still in idle state. If not we where to
     * slow with processing the received frame and the master sent another
     * frame on the network. We have to abort sending the frame.
     */
    if( eRcvState == STATE_RX_IDLE )
    {
        /* First byte before the Modbus-PDU is the slave address. */
        pucSndBufferCur = ( UCHAR * ) pucFrame - 1;
        usSndBufferCount = 1;

        /* Now copy the Modbus-PDU into the Modbus-Serial-Line-PDU. */
        pucSndBufferCur[MB_SER_PDU_ADDR_OFF] = ucSlaveAddress;
        usSndBufferCount += usLength;

        /* Calculate LRC checksum for Modbus-Serial-Line-PDU. */
        usLRC = prvucMBLRC( ( UCHAR * ) pucSndBufferCur, usSndBufferCount );
        ucASCIIBuf[usSndBufferCount++] = usLRC;

        /* Activate the transmitter. */
        eSndState = STATE_TX_START;
        vMBPortSerialEnable( FALSE, TRUE );
    }
    else
    {
        eStatus = MB_EIO;
    }
    EXIT_CRITICAL_SECTION(  );
    return eStatus;
}

BOOL
xMBASCIIReceiveFSM( void )
{
    BOOL            xNeedPoll = FALSE;
    UCHAR           ucByte;
    UCHAR           ucResult;

    assert( eSndState == STATE_TX_IDLE );

    ( void )xMBPortSerialGetByte( ( CHAR * ) & ucByte );
    switch ( eRcvState )
    {
        /* A new character is received. If the character is a ':' the input
         * buffer is cleared. A CR-character signals the end of the data
         * block. Other characters are part of the data block and their
         * ASCII value is converted back to a binary representation.
         */
    case STATE_RX_RCV:
        /* Enable timer for character timeout. */
        vMBPortTimersEnable(  );
        if( ucByte == ':' )
        {
            /* Empty receive buffer. */