mbascii.c

modbus的例程,非常不错,大家可以

 /*
  * FreeModbus Libary: A portable Modbus implementation for Modbus ASCII/RTU.
  * Copyright (C) 2006 Christian Walter <[e-mail]>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with this library; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  *
  * File: $Id: mbascii.c,v 1.11 2006/06/18 09:57:03 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;

    ENTER_CRITICAL_SECTION(  );
    ucMBLFCharacter = MB_ASCII_DEFAULT_LF;

    if( xMBPortSerialInit( ucPort, ulBaudRate, 7, eParity ) != TRUE )
    {
        eStatus = MB_EPORTERR;
    }

    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 = 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( &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. */
                eBytePos = BYTE_HIGH_NIBBLE;
                usRcvBufferPos = 0;
            }
            else if( ucByte == MB_ASCII_DEFAULT_CR )
            {