Tooltron

/* 

 * FreeModbus Libary: A portable Modbus implementation for Modbus ASCII/RTU.

 * Copyright (c) 2006 Christian Walter <wolti@sil.at>

 * 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 1.17 2010/06/06 13:47:07 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 too

     * 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. */

            eBytePos = BYTE_HIGH_NIBBLE;

            usRcvBufferPos = 0;

        }

        else if( ucByte == MB_ASCII_DEFAULT_CR )

        {

            eRcvState = STATE_RX_WAIT_EOF;

        }

        else

        {

            ucResult = prvucMBCHAR2BIN( ucByte );

            switch ( eBytePos )

            {

                /* High nibble of the byte comes first. We check for

                 * a buffer overflow here. */

            case BYTE_HIGH_NIBBLE:

                if( usRcvBufferPos < MB_SER_PDU_SIZE_MAX )

                {

                    ucASCIIBuf[usRcvBufferPos] = ( UCHAR )( ucResult << 4 );

                    eBytePos = BYTE_LOW_NIBBLE;

                    break;

                }

                else

                {

                    /* not handled in Modbus specification but seems

                     * a resonable implementation. */

                    eRcvState = STATE_RX_IDLE;

                    /* Disable previously activated timer because of error state. */

                    vMBPortTimersDisable(  );

                }

                break;

            case BYTE_LOW_NIBBLE:

                ucASCIIBuf[usRcvBufferPos] |= ucResult;

                usRcvBufferPos++;

                eBytePos = BYTE_HIGH_NIBBLE;

                break;

            }

        }

        break;

    case STATE_RX_WAIT_EOF:

        if( ucByte == ucMBLFCharacter )

        {

            /* Disable character timeout timer because all characters are

             * received. */

            vMBPortTimersDisable(  );

            /* Receiver is again in idle state. */

            eRcvState = STATE_RX_IDLE;

            /* Notify the caller of eMBASCIIReceive that a new frame

             * was received. */

            xNeedPoll = xMBPortEventPost( EV_FRAME_RECEIVED );

        }

        else if( ucByte == ':' )

        {

            /* Empty receive buffer and back to receive state. */

            eBytePos = BYTE_HIGH_NIBBLE;

            usRcvBufferPos = 0;

            eRcvState = STATE_RX_RCV;

            /* Enable timer for character timeout. */

            vMBPortTimersEnable(  );

        }

        else

        {

            /* Frame is not okay. Delete entire frame. */

            eRcvState = STATE_RX_IDLE;

        }

        break;

    case STATE_RX_IDLE:

        if( ucByte == ':' )

        {

            /* Enable timer for character timeout. */

            vMBPortTimersEnable(  );

            /* Reset the input buffers to store the frame. */

            usRcvBufferPos = 0;;

            eBytePos = BYTE_HIGH_NIBBLE;

            eRcvState = STATE_RX_RCV;

        }

        break;

    }

    return xNeedPoll;

}

BOOL

xMBASCIITransmitFSM( void )

{

    BOOL            xNeedPoll = FALSE;

    UCHAR           ucByte;

    assert( eRcvState == STATE_RX_IDLE );

    switch ( eSndState )

    {

        /* Start of transmission. The start of a frame is defined by sending

         * the character ':'. */

    case STATE_TX_START:

        ucByte = ':';

        xMBPortSerialPutByte( ( CHAR )ucByte );

        eSndState = STATE_TX_DATA;

        eBytePos = BYTE_HIGH_NIBBLE;

        break;

        /* Send the data block. Each data byte is encoded as a character hex

         * stream with the high nibble sent first and the low nibble sent

         * last. If all data bytes are exhausted we send a '\r' character

         * to end the transmission. */

    case STATE_TX_DATA:

        if( usSndBufferCount > 0 )

        {

            switch ( eBytePos )

            {

            case BYTE_HIGH_NIBBLE:

                ucByte = prvucMBBIN2CHAR( ( UCHAR )( *pucSndBufferCur >> 4 ) );

                xMBPortSerialPutByte( ( CHAR ) ucByte );

                eBytePos = BYTE_LOW_NIBBLE;

                break;

            case BYTE_LOW_NIBBLE:

                ucByte = prvucMBBIN2CHAR( ( UCHAR )( *pucSndBufferCur & 0x0F ) );

                xMBPortSerialPutByte( ( CHAR )ucByte );

                pucSndBufferCur++;

                eBytePos = BYTE_HIGH_NIBBLE;

                usSndBufferCount--;

                break;

            }

        }

        else

        {

            xMBPortSerialPutByte( MB_ASCII_DEFAULT_CR );

            eSndState = STATE_TX_END;

        }

        break;

        /* Finish the frame by sending a LF character. */

    case STATE_TX_END:

        xMBPortSerialPutByte( ( CHAR )ucMBLFCharacter );

        /* We need another state to make sure that the CR character has

         * been sent. */

        eSndState = STATE_TX_NOTIFY;

        break;

        /* Notify the task which called eMBASCIISend that the frame has

         * been sent. */

    case STATE_TX_NOTIFY:

        eSndState = STATE_TX_IDLE;

        xNeedPoll = xMBPortEventPost( EV_FRAME_SENT );

        /* Disable transmitter. This prevents another transmit buffer

         * empty interrupt. */

        vMBPortSerialEnable( TRUE, FALSE );

        eSndState = STATE_TX_IDLE;

        break;

        /* We should not get a transmitter event if the transmitter is in

         * idle state.  */

    case STATE_TX_IDLE:

        /* enable receiver/disable transmitter. */

        vMBPortSerialEnable( TRUE, FALSE );

        break;

    }

    return xNeedPoll;

}

BOOL

xMBASCIITimerT1SExpired( void )

{

    switch ( eRcvState )

    {

        /* If we have a timeout we go back to the idle state and wait for

         * the next frame.

         */

    case STATE_RX_RCV:

    case STATE_RX_WAIT_EOF:

        eRcvState = STATE_RX_IDLE;

        break;

    default:

        assert( ( eRcvState == STATE_RX_RCV ) || ( eRcvState == STATE_RX_WAIT_EOF ) );

        break;

    }

    vMBPortTimersDisable(  );

    /* no context switch required. */

    return FALSE;

}

static          UCHAR

prvucMBCHAR2BIN( UCHAR ucCharacter )

{

    if( ( ucCharacter >= '0' ) && ( ucCharacter <= '9' ) )

    {

        return ( UCHAR )( ucCharacter - '0' );

    }

    else if( ( ucCharacter >= 'A' ) && ( ucCharacter <= 'F' ) )

    {

        return ( UCHAR )( ucCharacter - 'A' + 0x0A );

    }

    else

    {

        return 0xFF;

    }

}

static          UCHAR

prvucMBBIN2CHAR( UCHAR ucByte )

{

    if( ucByte <= 0x09 )

    {

        return ( UCHAR )( '0' + ucByte );

    }

    else if( ( ucByte >= 0x0A ) && ( ucByte <= 0x0F ) )

    {

        return ( UCHAR )( ucByte - 0x0A + 'A' );

    }

    else

    {

        /* Programming error. */

        assert( 0 );

    }

    return '0';

}

static          UCHAR

prvucMBLRC( UCHAR * pucFrame, USHORT usLen )

{

    UCHAR           ucLRC = 0;  /* LRC char initialized */

    while( usLen-- )

    {

        ucLRC += *pucFrame++;   /* Add buffer byte without carry */

    }

    /* Return twos complement */

    ucLRC = ( UCHAR ) ( -( ( CHAR ) ucLRC ) );

    return ucLRC;

}

#endif