mbfuncinput.c

modbus的例程,非常不错,大家可以

 /*
  * FreeRTOS Modbus Libary: A Modbus serial implementation for FreeRTOS
  * 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
  */

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

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

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

/* ----------------------- Defines ------------------------------------------*/
#define MB_PDU_FUNC_READ_ADDR_OFF           ( MB_PDU_DATA_OFF )
#define MB_PDU_FUNC_READ_REGCNT_OFF         ( MB_PDU_DATA_OFF + 2 )
#define MB_PDU_FUNC_READ_SIZE               ( 4 )
#define MB_PDU_FUNC_READ_REGCNT_MAX         ( 0x007D )

#define MB_PDU_FUNC_READ_RSP_BYTECNT_OFF    ( MB_PDU_DATA_OFF )

/* ----------------------- Static functions ---------------------------------*/
eMBException    prveMBError2Exception( eMBErrorCode eErrorCode );

/* ----------------------- Start implementation -----------------------------*/
#if MB_FUNC_READ_INPUT_ENABLED > 0

eMBException
eMBFuncReadInputRegister( UCHAR * pucFrame, USHORT * usLen )
{
    USHORT          usRegAddress;
    USHORT          usRegCount;
    UCHAR          *pucFrameCur;

    eMBException    eStatus = MB_EX_NONE;
    eMBErrorCode    eRegStatus;

    if( *usLen == ( MB_PDU_FUNC_READ_SIZE + MB_PDU_SIZE_MIN ) )
    {
        usRegAddress = pucFrame[MB_PDU_FUNC_READ_ADDR_OFF] << 8;
        usRegAddress |= pucFrame[MB_PDU_FUNC_READ_ADDR_OFF + 1];
        usRegAddress++;

        usRegCount = pucFrame[MB_PDU_FUNC_READ_REGCNT_OFF] << 8;
        usRegCount = pucFrame[MB_PDU_FUNC_READ_REGCNT_OFF + 1];

        /* Check if the number of registers to read is valid. If not
         * return Modbus illegal data value exception. 
         */
        if( ( usRegCount >= 1 )
            && ( usRegCount < MB_PDU_FUNC_READ_REGCNT_MAX ) )
        {
            /* Set the current PDU data pointer to the beginning. */
            pucFrameCur = &pucFrame[MB_PDU_FUNC_OFF];
            *usLen = MB_PDU_FUNC_OFF;

            /* First byte contains the function code. */
            *pucFrameCur++ = MB_FUNC_READ_INPUT_REGISTER;
            *usLen += 1;

            /* Second byte in the response contain the number of bytes. */
            *pucFrameCur++ = ( UCHAR )( usRegCount * 2 );
            *usLen += 1;

            eRegStatus =
                eMBRegInputCB( pucFrameCur, usRegAddress, usRegCount );

            /* If an error occured convert it into a Modbus exception. */
            if( eRegStatus != MB_ENOERR )
            {
                eStatus = prveMBError2Exception( eRegStatus );
            }
            else
            {
                *usLen += usRegCount * 2;
            }
        }
        else
        {
            eStatus = MB_EX_ILLEGAL_DATA_VALUE;
        }
    }
    else
    {
        /* Can't be a valid read input register request because the length
         * is incorrect. */
        eStatus = MB_EX_ILLEGAL_DATA_VALUE;
    }
    return eStatus;
}

#endif