freemodbus教程之freemodbus移植应用串口中断接收和数据解析

     freemodbus教程之freemodbus移植应用串口中断接收和数据解析                    本篇主要讲解从机数据的接收流程。接收流程分为两个阶段：串口中断接收和数据解析。第一阶段：中断接收函数prvvUARTRxISR（xMBRTUReceiveFSM）和定时器中断回调函数xMBRTUTImerT35Expired（），第二阶段：数据解析eMBPoll()。一、串口中断接收从机正常状态下，串口设置为接收中断模式，也不启动定时器。当检测到有数据时，中断函数调用xMBRTUReceiveFSM（）函数，通过该函数中的ucRTUBuf数组存储接收帧，用usRcvBufferPos存储数据帧长度。具体函数：1、中断接收函数。voidUART1_IRQ(void){IF(USART_GeTITStatus(USART1,USART_IT_TXE)){pxMBFrameCBTransmitterEmpty();}elseif(USART_GeTITStatus(USART1,USART_IT_RXNE))//接收中断{pxMBFrameCBByteReceived();//pxMBFrameCBByteReceived=xMBRTUReceiveFSM;}}2、xMBRTUReceiveFSM（）函数。RTU接收状态函数。只要进人该函数，就会启动定时器中断。从机的接收状态：（１）STATE_RX_INIT（栈初始化）；（2）STATE_RX_ERROR（接收错误）；（3）STATE_RX_IDLE（接收空闲，接收帧头，常用）；（4）STATE_RX_RCV（接收所有数据，常用）。注意：接收数据时，只要接收到数据，定时器就会清零，重新计数。BOOLxMBRTUReceiveFSM(void){BOOLxTaskNeedSwitch=FALSE;UCHARucByte;assert(eSndState==STATE_TX_IDLE);/*Alwaysreadthecharacter.*/(void)xMBPortSerialGetByte((CHAR*)&ucByte);switch(eRcvState){/*Ifwehavereceivedacharacterintheinitstatewehaveto*waitunTIltheframeisfinished.*/caseSTATE_RX_INIT:vMBPortTimersEnable();break;/*Intheerrorstatewewaituntilallcharactersinthe*damagedframearetransmitted.*/caseSTATE_RX_ERROR:vMBPortTimersEnable();break;/*Intheidlestatewewaitforanewcharacter.Ifacharacter*isreceivedthet1.5andt3.5timersarestartedandthe*receiverisinthestateSTATE_RX_RECEIVCE.*/caseSTATE_RX_IDLE:usRcvBufferPos=0;ucRTUBuf[usRcvBufferPos++]=ucByte;eRcvState=STATE_RX_RCV;/*Enablet3.5timers.*/vMBPortTimersEnable();break;/*Wearecurrentlyreceivingaframe.Resetthetimerafter*everycharacterreceived.Ifmorethanthemaximumpossible*numberofbytesinamodbusframeisreceivedtheframeis*ignored.*/caseSTATE_RX_RCV:if(usRcvBufferPos0{MB_FUNC_OTHER_REPORT_SLAVEID,eMBFuncReportSlaveID},#endif#ifMB_FUNC_READ_INPUT_ENABLED>0{MB_FUNC_READ_INPUT_REGISTER,eMBFuncReadInputRegister},#endif#ifMB_FUNC_READ_HOLDING_ENABLED>0{MB_FUNC_READ_HOLDING_REGISTER,eMBFuncReadHoldingRegister},#endif#ifMB_FUNC_WRITE_MULTIPLE_HOLDING_ENABLED>0{MB_FUNC_WRITE_MULTIPLE_REGISTERS,eMBFuncWriteMultipleHoldingRegister},#endif#ifMB_FUNC_WRITE_HOLDING_ENABLED>0{MB_FUNC_WRITE_REGISTER,eMBFuncWriteHoldingRegister},#endif#ifMB_FUNC_READWRITE_HOLDING_ENABLED>0{MB_FUNC_READWRITE_MULTIPLE_REGISTERS,eMBFuncReadWriteMultipleHoldingRegister},#endif#ifMB_FUNC_READ_COILS_ENABLED>0{MB_FUNC_READ_COILS,eMBFuncReadCoils},#endif#ifMB_FUNC_WRITE_COIL_ENABLED>0{MB_FUNC_WRITE_SINGLE_COIL,eMBFuncWriteCoil},#endif#ifMB_FUNC_WRITE_MULTIPLE_COILS_ENABLED>0{MB_FUNC_WRITE_MULTIPLE_COILS,eMBFuncWriteMultipleCoils},#endif#ifMB_FUNC_READ_DISCRETE_INPUTS_ENABLED>0{MB_FUNC_READ_DISCRETE_INPUTS,eMBFuncReadDiscreteInputs},#endif};以功能码04为例，读取输入寄存器。eMBExceptioneMBFuncReadInputRegister(UCHAR*pucFrame,USHORT*usLen){USHORTusRegAddress;USHORTusRegCount;UCHAR*pucFrameCur;eMBExceptioneStatus=MB_EX_NONE;eMBErrorCodeeRegStatus;if(*usLen==(MB_PDU_FUNC_READ_SIZE+MB_PDU_SIZE_MIN))//计算帧长度，除了地址位和两位的crc校验位{usRegAddress=(USHORT)(pucFrame[MB_PDU_FUNC_READ_ADDR_OFF]<<8);//读取寄存器的首地址usRegAddress|=(USHORT)(pucFrame[MB_PDU_FUNC_READ_ADDR_OFF+1]);usRegAddress++;usRegCount=(USHORT)(pucFrame[MB_PDU_FUNC_READ_REGCNT_OFF]<<8);//计算读取寄存器的长度usRegCount|=(USHORT)(pucFrame[MB_PDU_FUNC_READ_REGCNT_OFF+1]);/*Checkifthenumberofregisterstoreadisvalid.Ifnot*returnModbusillegaldatavalueexception.*/if((usRegCount>=1)&&(usRegCount=REG_INPUT_START)&&(usAddress+usNRegs<=REG_INPUT_START+REG_INPUT_NREGS)){iRegIndex=(int)(usAddress-REG_INPUT_START);while(usNRegs>0){*pucRegBuffer++=(unsignedchar)(usRegInputBuf[iRegIndex]>>8);*pucRegBuffer++=(unsignedchar)(usRegInputBuf[iRegIndex]&0xFF);iRegIndex++;usNRegs--;}}else{eStatus=MB_ENOREG;}returneStatus;}以上就是整个接收数据、解析数据的过程。来源：csdn博客萧年已逝；在此特别鸣谢！ -全文完-