mbfuncinput.cpp

00001 /* 
00002  * FreeModbus Libary: A portable Modbus implementation for Modbus ASCII/RTU.
00003  * Copyright (c) 2006 Christian Walter <wolti@sil.at>
00004  * All rights reserved.
00005  *
00006  * Redistribution and use in source and binary forms, with or without
00007  * modification, are permitted provided that the following conditions
00008  * are met:
00009  * 1. Redistributions of source code must retain the above copyright
00010  *    notice, this list of conditions and the following disclaimer.
00011  * 2. Redistributions in binary form must reproduce the above copyright
00012  *    notice, this list of conditions and the following disclaimer in the
00013  *    documentation and/or other materials provided with the distribution.
00014  * 3. The name of the author may not be used to endorse or promote products
00015  *    derived from this software without specific prior written permission.
00016  *
00017  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
00018  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
00019  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
00020  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
00021  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
00022  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
00023  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
00024  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
00025  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
00026  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
00027  *
00028  * File: $Id: mbfuncinput.c,v 1.10 2007/09/12 10:15:56 wolti Exp $
00029  */
00030 
00031 /* ----------------------- System includes ----------------------------------*/
00032 #include "stdlib.h"
00033 #include "string.h"
00034 
00035 /* ----------------------- Platform includes --------------------------------*/
00036 #include "port.h"
00037 
00038 /* ----------------------- Modbus includes ----------------------------------*/
00039 #include "mb.h"
00040 #include "mbframe.h"
00041 #include "mbproto.h"
00042 #include "mbconfig.h"
00043 
00044 /* ----------------------- Defines ------------------------------------------*/
00045 #define MB_PDU_FUNC_READ_ADDR_OFF           ( MB_PDU_DATA_OFF )
00046 #define MB_PDU_FUNC_READ_REGCNT_OFF         ( MB_PDU_DATA_OFF + 2 )
00047 #define MB_PDU_FUNC_READ_SIZE               ( 4 )
00048 #define MB_PDU_FUNC_READ_REGCNT_MAX         ( 0x007D )
00049 
00050 #define MB_PDU_FUNC_READ_RSP_BYTECNT_OFF    ( MB_PDU_DATA_OFF )
00051 
00052 /* ----------------------- Static functions ---------------------------------*/
00053 eMBException    prveMBError2Exception( eMBErrorCode eErrorCode );
00054 
00055 /* ----------------------- Start implementation -----------------------------*/
00056 #if MB_FUNC_READ_INPUT_ENABLED > 0
00057 
00058 eMBException
00059 eMBFuncReadInputRegister( UCHAR * pucFrame, USHORT * usLen )
00060 {
00061     USHORT          usRegAddress;
00062     USHORT          usRegCount;
00063     UCHAR          *pucFrameCur;
00064 
00065     eMBException    eStatus = MB_EX_NONE;
00066     eMBErrorCode    eRegStatus;
00067 
00068     if( *usLen == ( MB_PDU_FUNC_READ_SIZE + MB_PDU_SIZE_MIN ) )
00069     {
00070         usRegAddress = ( USHORT )( pucFrame[MB_PDU_FUNC_READ_ADDR_OFF] << 8 );
00071         usRegAddress |= ( USHORT )( pucFrame[MB_PDU_FUNC_READ_ADDR_OFF + 1] );
00072         usRegAddress++;
00073 
00074         usRegCount = ( USHORT )( pucFrame[MB_PDU_FUNC_READ_REGCNT_OFF] << 8 );
00075         usRegCount |= ( USHORT )( pucFrame[MB_PDU_FUNC_READ_REGCNT_OFF + 1] );
00076 
00077         /* Check if the number of registers to read is valid. If not
00078          * return Modbus illegal data value exception. 
00079          */
00080         if( ( usRegCount >= 1 )
00081             && ( usRegCount < MB_PDU_FUNC_READ_REGCNT_MAX ) )
00082         {
00083             /* Set the current PDU data pointer to the beginning. */
00084             pucFrameCur = &pucFrame[MB_PDU_FUNC_OFF];
00085             *usLen = MB_PDU_FUNC_OFF;
00086 
00087             /* First byte contains the function code. */
00088             *pucFrameCur++ = MB_FUNC_READ_INPUT_REGISTER;
00089             *usLen += 1;
00090 
00091             /* Second byte in the response contain the number of bytes. */
00092             *pucFrameCur++ = ( UCHAR )( usRegCount * 2 );
00093             *usLen += 1;
00094 
00095             eRegStatus = eMBRegInputCB( pucFrameCur, usRegAddress, usRegCount );
00096 
00097             /* If an error occured convert it into a Modbus exception. */
00098             if( eRegStatus != MB_ENOERR  )
00099             {
00100                 eStatus = prveMBError2Exception( eRegStatus );
00101             }
00102             else
00103             {
00104                 *usLen += usRegCount * 2;
00105             }
00106         }
00107         else
00108         {
00109             eStatus = MB_EX_ILLEGAL_DATA_VALUE;
00110         }
00111     }
00112     else
00113     {
00114         /* Can't be a valid read input register request because the length
00115          * is incorrect. */
00116         eStatus = MB_EX_ILLEGAL_DATA_VALUE;
00117     }
00118     return eStatus;
00119 }
00120 
00121 #endif