日志

FreeModbus Slave 改进的eMbPoll()【worldsing 笔记】

热度 3已有 4483 次阅读2013-8-14 12:35 |个人分类:Modbus|系统分类:单片机| 通信, 主机

eMbPoll()的作用是FreeMod协议通信过程中不断查询事件对列有无完速数据桢，并进行地址和CRD验证，最后运行和回复主机。

为了减小代码尺寸对eMbPoll进行改进：

原版：

eMBErrorCode

eMBPoll( void )

{

static UCHAR *ucMBFrame;

static UCHAR ucRcvAddress;

static UCHAR ucFunctionCode;

static USHORT usLength;

static eMBException eException;

int i;

eMBErrorCode eStatus = MB_ENOERR;

eMBEventType eEvent;

/* Check if the protocol stack is ready. */

if( eMBState != STATE_ENABLED )

{

return MB_EILLSTATE;

}

/* Check if there is a event available. If not return control to caller.

* Otherwise we will handle the event. */

//查询事件

if( xMBPortEventGet( &eEvent ) == TRUE )

{

switch ( eEvent )

{

case EV_READY:

break;

case EV_FRAME_RECEIVED:

//接收报文函数，传入参数从机地址，报文指针，长度

//实际上调用了eMBRTUReceive 位于mbrtu.c

eStatus = peMBFrameReceiveCur( &ucRcvAddress, &ucMBFrame, &usLength );

if( eStatus == MB_ENOERR )

{

/* Check if the frame is for us. If not ignore the frame. */

//验证报文从机地址

if( ( ucRcvAddress == ucMBAddress ) || ( ucRcvAddress == MB_ADDRESS_BROADCAST ) )

{

//发送事件，报文到达，可以进行处理

( void )xMBPortEventPost( EV_EXECUTE );

}

break;

case EV_EXECUTE:

ucFunctionCode = ucMBFrame[MB_PDU_FUNC_OFF];

eException = MB_EX_ILLEGAL_FUNCTION;

for( i = 0; i < MB_FUNC_HANDLERS_MAX; i++ )

{

/* No more function handlers registered. Abort. */

if( xFuncHandlers[i].ucFunctionCode == 0 )

{

break;

}

else if( xFuncHandlers[i].ucFunctionCode == ucFunctionCode )

{

eException = xFuncHandlers[i].pxHandler( ucMBFrame, &usLength );

break;

}

/* If the request was not sent to the broadcast address we

* return a reply. */

if( ucRcvAddress != MB_ADDRESS_BROADCAST )

{

if( eException != MB_EX_NONE )

{

/* An exception occured. Build an error frame. */

usLength = 0;

ucMBFrame[usLength++] = ( UCHAR )( ucFunctionCode | MB_FUNC_ERROR );

ucMBFrame[usLength++] = eException;

}

if( ( eMBCurrentMode == MB_ASCII ) && MB_ASCII_TIMEOUT_WAIT_BEFORE_SEND_MS )

{

vMBPortTimersDelay( MB_ASCII_TIMEOUT_WAIT_BEFORE_SEND_MS );

}

eStatus = peMBFrameSendCur( ucMBAddress, ucMBFrame, usLength );

}

break;

case EV_FRAME_SENT:

break;

}

return MB_ENOERR;

}

改进后的eMbPoll():

void eMBPoll( void ){
  
  static UCHAR   *ucMBFrame;
  static UCHAR    ucFunctionCode;
  static USHORT   usLength;
  static eMBException eException;
  eMBEventType    eEvent;
  UCHAR i;
  USHORT usCRC16;
  if(xMBPortEventGet( &eEvent) == TRUE ){                             //桢事件判断
    if(eEvent == EV_FRAME_RECEIVED){    
      if(usRcvBufferPos < MB_SER_PDU_SIZE_MIN)                        //最小桢判断
        return;
      if(usMBCRC16((UCHAR *)ucRTUBuf, usRcvBufferPos ) != 0)          //CRC判断
        return;
      if(IS_VALID_ADD){                                               //地址        
        ucMBFrame = (UCHAR *) &ucRTUBuf[MB_SER_PDU_PDU_OFF];        
        usLength = (USHORT)( usRcvBufferPos - MB_SER_PDU_PDU_OFF - MB_SER_PDU_SIZE_CRC);
        ucFunctionCode = ucMBFrame[MB_PDU_FUNC_OFF];
        eException = MB_EX_ILLEGAL_FUNCTION;
        for(i = 0; i < MB_FUNC_HANDLERS_MAX; i++ ){                  //执行功能码
          if( xFuncHandlers[i].ucFunctionCode == 0 ){
            return;
          }
          else if( xFuncHandlers[i].ucFunctionCode == ucFunctionCode ){
            eException = xFuncHandlers[i].pxHandler( ucMBFrame, &usLength );
            break;                               
          }
      }
      if(IS_NOT_BROADCAST){                                        //回复主机
        if( eException != MB_EX_NONE ){                            //错误码         
          usLength = 0;
          ucMBFrame[usLength++] = ( UCHAR )( ucFunctionCode | MB_FUNC_ERROR );
          ucMBFrame[usLength++] = eException;
        } 
        if(eRcvState == STATE_RX_IDLE){                            //发送
          pucSndBufferCur = ( UCHAR * ) ucMBFrame - 1;
          pucSndBufferCur[MB_SER_PDU_ADDR_OFF] = ucMBAddress;
          usSndBufferCount = usLength + 1;      
          usCRC16 = usMBCRC16( ( UCHAR * ) pucSndBufferCur, usSndBufferCount );
          ucRTUBuf[usSndBufferCount++] = ( UCHAR )( usCRC16 & 0xFF );
          ucRTUBuf[usSndBufferCount++] = ( UCHAR )( usCRC16 >> 8 );    
          eSndState = STATE_TX_XMIT;
          vMBPortSerialEnable( FALSE, TRUE );
          }//发送结束
        }//回复结束
      }//地址判断
    }//桢事件判断
  }
}