text:  /*
    * FreeRTOS Modbus Libary: A Modbus serial implementation for FreeRTOS
    * Copyright (C) 2006 Christian Walter <wolti@sil.at>
    *
    * 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"
  
  /* if  MB_DEVICE_USE_TYPE == MB_DEVICE_MASTER  */
  
  
  /* ----------------------- Defines ------------------------------------------*/
  #define MB_PDU_REQ_READ_ADDR_OFF            ( MB_PDU_DATA_OFF + 0 )
  #define MB_PDU_REQ_READ_DISCCNT_OFF         ( MB_PDU_DATA_OFF + 2 )
  #define MB_PDU_REQ_READ_SIZE                ( 4 )
  #define MB_PDU_FUNC_READ_DISCCNT_OFF        ( MB_PDU_DATA_OFF + 0 )
  #define MB_PDU_FUNC_READ_VALUES_OFF         ( MB_PDU_DATA_OFF + 1 )
  #define MB_PDU_FUNC_READ_SIZE_MIN           ( 1 )
  
  /* ----------------------- Static functions ---------------------------------*/
  eMBException    prveMBError2Exception( eMBErrorCode eErrorCode );
  
  /* ----------------------- Start implementation -----------------------------*/
  #if MB_ASCII_ENABLED > 0 || MB_RTU_ENABLED > 0
  #if MB_FUNC_READ_DISCRETE_INPUTS_ENABLED > 0
  
  /**
   * This function will request read discrete inputs.
   *
   * @param ucSndAddr salve address
   * @param usDiscreteAddr discrete start address
   * @param usNDiscreteIn discrete total number
   * @param lTimeOut timeout (-1 will waiting forever)
   *
   * @return error code
   */
  eMBMasterReqErrCode
  eMBMasterReqReadDiscreteInputs( UCHAR ucSndAddr, USHORT usDiscreteAddr, USHORT usNDiscreteIn, LONG lTimeOut )
  {
      UCHAR                 *ucMBFrame;
      eMBMasterReqErrCode    eErrStatus = MB_MRE_NO_ERR;
  
      if ( ucSndAddr > MB_MASTER_TOTAL_SLAVE_NUM ) eErrStatus = MB_MRE_ILL_ARG;
      else if ( xMBMasterRunResTake( lTimeOut ) == FALSE ) eErrStatus = MB_MRE_MASTER_BUSY;
      else
      {
  		vMBMasterGetPDUSndBuf(&ucMBFrame);
  		vMBMasterSetDestAddress(ucSndAddr);
  		ucMBFrame[MB_PDU_FUNC_OFF]                 = MB_FUNC_READ_DISCRETE_INPUTS;
  		ucMBFrame[MB_PDU_REQ_READ_ADDR_OFF]        = usDiscreteAddr >> 8;
  		ucMBFrame[MB_PDU_REQ_READ_ADDR_OFF + 1]    = usDiscreteAddr;
  		ucMBFrame[MB_PDU_REQ_READ_DISCCNT_OFF ]    = usNDiscreteIn >> 8;
  		ucMBFrame[MB_PDU_REQ_READ_DISCCNT_OFF + 1] = usNDiscreteIn;
  		vMBMasterSetPDUSndLength( MB_PDU_SIZE_MIN + MB_PDU_REQ_READ_SIZE );
  		( void ) xMBMasterPortEventPost( EV_MASTER_FRAME_SENT );
  		eErrStatus = eMBMasterWaitRequestFinish( );
      }
      return eErrStatus;
  }
  
  eMBException
  eMBMasterFuncReadDiscreteInputs( UCHAR * pucFrame, USHORT * usLen )
  {
      USHORT          usRegAddress;
      USHORT          usDiscreteCnt;
      UCHAR           ucNBytes;
      UCHAR          *ucMBFrame;
  
      eMBException    eStatus = MB_EX_NONE;
      eMBErrorCode    eRegStatus;
  
      /* If this request is broadcast, and it's read mode. This request don't need execute. */
      if ( xMBMasterRequestIsBroadcast() )
      {
      	eStatus = MB_EX_NONE;
      }
      else if( *usLen >= MB_PDU_SIZE_MIN + MB_PDU_FUNC_READ_SIZE_MIN )
      {
      	vMBMasterGetPDUSndBuf(&ucMBFrame);
          usRegAddress = ( USHORT )( ucMBFrame[MB_PDU_REQ_READ_ADDR_OFF] << 8 );
          usRegAddress |= ( USHORT )( ucMBFrame[MB_PDU_REQ_READ_ADDR_OFF + 1] );
          usRegAddress++;
  
          usDiscreteCnt = ( USHORT )( ucMBFrame[MB_PDU_REQ_READ_DISCCNT_OFF] << 8 );
          usDiscreteCnt |= ( USHORT )( ucMBFrame[MB_PDU_REQ_READ_DISCCNT_OFF + 1] );
  
          /* Test if the quantity of coils is a multiple of 8. If not last
           * byte is only partially field with unused coils set to zero. */
          if( ( usDiscreteCnt & 0x0007 ) != 0 )
          {
          	ucNBytes = ( UCHAR )( usDiscreteCnt / 8 + 1 );
          }
          else
          {
          	ucNBytes = ( UCHAR )( usDiscreteCnt / 8 );
          }
  
          /* Check if the number of registers to read is valid. If not
           * return Modbus illegal data value exception. 
           */
  		if ((usDiscreteCnt >= 1) && ucNBytes == pucFrame[MB_PDU_FUNC_READ_DISCCNT_OFF])
          {
  	       	/* Make callback to fill the buffer. */
  			eRegStatus = eMBMasterRegDiscreteCB( &pucFrame[MB_PDU_FUNC_READ_VALUES_OFF], usRegAddress, usDiscreteCnt );
  
  			/* If an error occured convert it into a Modbus exception. */
  			if( eRegStatus != MB_ENOERR )
  			{
  				eStatus = prveMBError2Exception( eRegStatus );
  			}
          }
          else
          {
              eStatus = MB_EX_ILLEGAL_DATA_VALUE;
          }
      }
      else
      {
          /* Can't be a valid read coil register request because the length
           * is incorrect. */
          eStatus = MB_EX_ILLEGAL_DATA_VALUE;
      }
      return eStatus;
  }
  
  #endif
  #endif
  