126 lines
4.5 KiB
C
126 lines
4.5 KiB
C
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/*
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* FreeRTOS Modbus Libary: A Modbus serial implementation for FreeRTOS
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* Copyright (C) 2006 Christian Walter <wolti@sil.at>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/* ----------------------- System includes ----------------------------------*/
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#include "stdlib.h"
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#include "string.h"
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/* ----------------------- Platform includes --------------------------------*/
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#include "port.h"
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/* ----------------------- Modbus includes ----------------------------------*/
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#include "mb.h"
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#include "mbframe.h"
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#include "mbproto.h"
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#include "mbconfig.h"
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/* ----------------------- Defines ------------------------------------------*/
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#define MB_PDU_FUNC_READ_ADDR_OFF ( MB_PDU_DATA_OFF )
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#define MB_PDU_FUNC_READ_DISCCNT_OFF ( MB_PDU_DATA_OFF + 2 )
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#define MB_PDU_FUNC_READ_SIZE ( 4 )
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#define MB_PDU_FUNC_READ_DISCCNT_MAX ( 0x07D0 )
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/* ----------------------- Static functions ---------------------------------*/
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eMBException prveMBError2Exception( eMBErrorCode eErrorCode );
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/* ----------------------- Start implementation -----------------------------*/
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#if MB_FUNC_READ_COILS_ENABLED > 0
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eMBException
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eMBFuncReadDiscreteInputs( UCHAR * pucFrame, USHORT * usLen )
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{
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USHORT usRegAddress;
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USHORT usDiscreteCnt;
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UCHAR ucNBytes;
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UCHAR *pucFrameCur;
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eMBException eStatus = MB_EX_NONE;
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eMBErrorCode eRegStatus;
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if( *usLen == ( MB_PDU_FUNC_READ_SIZE + MB_PDU_SIZE_MIN ) )
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{
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usRegAddress = ( USHORT )( pucFrame[MB_PDU_FUNC_READ_ADDR_OFF] << 8 );
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usRegAddress |= ( USHORT )( pucFrame[MB_PDU_FUNC_READ_ADDR_OFF + 1] );
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usRegAddress++;
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usDiscreteCnt = ( USHORT )( pucFrame[MB_PDU_FUNC_READ_DISCCNT_OFF] << 8 );
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usDiscreteCnt |= ( USHORT )( pucFrame[MB_PDU_FUNC_READ_DISCCNT_OFF + 1] );
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/* Check if the number of registers to read is valid. If not
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* return Modbus illegal data value exception.
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*/
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if( ( usDiscreteCnt >= 1 ) &&
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( usDiscreteCnt < MB_PDU_FUNC_READ_DISCCNT_MAX ) )
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{
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/* Set the current PDU data pointer to the beginning. */
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pucFrameCur = &pucFrame[MB_PDU_FUNC_OFF];
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*usLen = MB_PDU_FUNC_OFF;
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/* First byte contains the function code. */
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*pucFrameCur++ = MB_FUNC_READ_DISCRETE_INPUTS;
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*usLen += 1;
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/* Test if the quantity of coils is a multiple of 8. If not last
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* byte is only partially field with unused coils set to zero. */
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if( ( usDiscreteCnt & 0x0007 ) != 0 )
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{
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ucNBytes = ( UCHAR ) ( usDiscreteCnt / 8 + 1 );
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}
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else
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{
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ucNBytes = ( UCHAR ) ( usDiscreteCnt / 8 );
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}
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*pucFrameCur++ = ucNBytes;
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*usLen += 1;
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eRegStatus =
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eMBRegDiscreteCB( pucFrameCur, usRegAddress, usDiscreteCnt );
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/* If an error occured convert it into a Modbus exception. */
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if( eRegStatus != MB_ENOERR )
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{
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eStatus = prveMBError2Exception( eRegStatus );
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}
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else
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{
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/* The response contains the function code, the starting address
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* and the quantity of registers. We reuse the old values in the
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* buffer because they are still valid. */
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*usLen += ucNBytes;;
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}
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}
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else
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{
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eStatus = MB_EX_ILLEGAL_DATA_VALUE;
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}
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}
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else
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{
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/* Can't be a valid read coil register request because the length
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* is incorrect. */
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eStatus = MB_EX_ILLEGAL_DATA_VALUE;
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}
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return eStatus;
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}
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#endif
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