在没有操作系统的标准库中将FreeModbus移植到STM32

添加FreeModbus代码

首先准备一个空白的标准库项目。

下载FreeModbus源码。

将源码中的modbus文件夹复制到项目路径下,并把demo->BARE->port文件夹的内容也添加进来。

新建一个文件port.c备用。然后打开项目,将上述文件添加至项目,最好是按照文件夹建立不同分组。

完成后的项目结构如下:

然后添加头文件路径,将modbus与port文件夹的内容包含。

修改代码

portserial.c

首先是串口文件portserial.c

void
vMBPortSerialEnable( BOOL xRxEnable, BOOL xTxEnable )
{
}

BOOL
xMBPortSerialInit( UCHAR ucPORT, ULONG ulBaudRate, UCHAR ucDataBits, eMBParity eParity )
{
    return FALSE;
}

BOOL
xMBPortSerialPutByte( CHAR ucByte )
{
    return TRUE;
}

BOOL
xMBPortSerialGetByte( CHAR * pucByte )
{
    return TRUE;
}

static void prvvUARTTxReadyISR( void )
{
    pxMBFrameCBTransmitterEmpty(  );
}

static void prvvUARTRxISR( void )
{
    pxMBFrameCBByteReceived(  );
}

我们进行以下修改

在vMBPortSerialEnable函数进行串口中断的使能与失能,其实是切换发送或者接收。FreeModbus使用中断来进行数据的收发,但是由于Modbus协议特性,同时只能开启一种中断,即不能进行同时收发。

根据参数xRxEnable与xTxEnable的值,开启或关闭对应中断。这里发送中断选择TC、接收中断选择RXNE。

void
vMBPortSerialEnable( BOOL xRxEnable, BOOL xTxEnable )
{
	if (xTxEnable)
	{
		USART_ITConfig(USART3,USART_IT_TC,ENABLE);
	}
	else
	{
		USART_ITConfig(USART3,USART_IT_TC,DISABLE);
	}
	if (xRxEnable)
	{
		USART_ITConfig(USART3,USART_IT_RXNE,ENABLE);
	}
	else
	{
		USART_ITConfig(USART3,USART_IT_RXNE,DISABLE);
	}
}

xMBPortSerialInit函数进行串口初始化。传入的参数是串口、波特率、数据位与校验位。根据传入的参数对串口初始化,初始化成功返回TRUE,否则返回FALSE。

可以通过传入的参数进行灵活初始化,也可以不管参数,将初始化写死。这里使用UART3,波特率与参数一致,停止位1位,无校验位

BOOL
xMBPortSerialInit( UCHAR ucPORT, ULONG ulBaudRate, UCHAR ucDataBits, eMBParity eParity )
{
	RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB,ENABLE);//打开串口3的GPIO时钟
	RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART3,ENABLE);//打开串口3时钟
	
	
	//配置USART3的RX,TX的GPIO口
	GPIO_InitTypeDef GPIO_InitStruct;
	GPIO_InitStruct.GPIO_Pin = GPIO_Pin_10; //将USART3_TX配置为复用推挽输出模式
	GPIO_InitStruct.GPIO_Mode = GPIO_Mode_AF_PP;
	GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz;
	GPIO_Init(GPIOB,&GPIO_InitStruct);
	GPIO_InitStruct.GPIO_Pin = GPIO_Pin_11; //将USART3_RX配置为浮空输入模式
	GPIO_InitStruct.GPIO_Mode = GPIO_Mode_IN_FLOATING;
	GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz;
	GPIO_Init(GPIOB,&GPIO_InitStruct);
	
	//配置USART3
	USART_InitTypeDef USART_InitStruct;
	USART_InitStruct.USART_WordLength = USART_WordLength_8b;
	USART_InitStruct.USART_StopBits = USART_StopBits_1;
	USART_InitStruct.USART_BaudRate = ulBaudRate;
	USART_InitStruct.USART_Parity = USART_Parity_No;
	USART_InitStruct.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
	USART_InitStruct.USART_Mode = USART_Mode_Rx|USART_Mode_Tx;
	USART_Init(USART3,&USART_InitStruct);
	USART_Cmd(USART3,ENABLE);
	
	//配置中断
	NVIC_InitTypeDef NVIC_InitStruct;
	NVIC_InitStruct.NVIC_IRQChannelCmd = ENABLE;
	NVIC_InitStruct.NVIC_IRQChannelPreemptionPriority = 1;
	NVIC_InitStruct.NVIC_IRQChannelSubPriority = 1;
	NVIC_InitStruct.NVIC_IRQChannel = USART3_IRQn;
	NVIC_Init(&NVIC_InitStruct);
  return TRUE;
}

xMBPortSerialPutByte与xMBPortSerialGetByte实现单字节收发

BOOL
xMBPortSerialPutByte( CHAR ucByte )
{
    USART_SendData(USART3,ucByte);
    return TRUE;
}

BOOL
xMBPortSerialGetByte( CHAR * pucByte )
{
    *pucByte = USART_ReceiveData(USART3);
    return TRUE;
}

实现串口的中断函数。要求是发生发送与接收中断时,调用对应的函数。

void USART3_IRQHandler(void)
{
	if(USART_GetITStatus(USART3, USART_IT_RXNE) == SET)
	{
		prvvUARTRxISR();  
		USART_ClearITPendingBit(USART3, USART_IT_RXNE);   
	}
	if(USART_GetITStatus(USART3, USART_IT_TC) == SET)
	{
		prvvUARTTxReadyISR();
		USART_ClearITPendingBit(USART3, USART_IT_TC);
	}
}

完整的portserial.c函数如下:

#include "port.h"
#include "stm32f10x.h"
/* ----------------------- Modbus includes ----------------------------------*/
#include "mb.h"
#include "mbport.h"

/* ----------------------- static functions ---------------------------------*/
static void prvvUARTTxReadyISR( void );
static void prvvUARTRxISR( void );

/* ----------------------- Start implementation -----------------------------*/
void
vMBPortSerialEnable( BOOL xRxEnable, BOOL xTxEnable )
{
	if (xTxEnable)
	{
		USART_ITConfig(USART3,USART_IT_TC,ENABLE);
	}
	else
	{
		USART_ITConfig(USART3,USART_IT_TC,DISABLE);
	}
	if (xRxEnable)
	{
		USART_ITConfig(USART3,USART_IT_RXNE,ENABLE);
	}
	else
	{
		USART_ITConfig(USART3,USART_IT_RXNE,DISABLE);
	}
}

BOOL
xMBPortSerialInit( UCHAR ucPORT, ULONG ulBaudRate, UCHAR ucDataBits, eMBParity eParity )
{
	RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB,ENABLE);//打开串口3的GPIO时钟
	RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART3,ENABLE);//打开串口3时钟
	
	
	//配置USART3的RX,TX的GPIO口
	GPIO_InitTypeDef GPIO_InitStruct;
	GPIO_InitStruct.GPIO_Pin = GPIO_Pin_10; //将USART3_TX配置为复用推挽输出模式
	GPIO_InitStruct.GPIO_Mode = GPIO_Mode_AF_PP;
	GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz;
	GPIO_Init(GPIOB,&GPIO_InitStruct);
	GPIO_InitStruct.GPIO_Pin = GPIO_Pin_11; //将USART3_RX配置为浮空输入模式
	GPIO_InitStruct.GPIO_Mode = GPIO_Mode_IN_FLOATING;
	GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz;
	GPIO_Init(GPIOB,&GPIO_InitStruct);
	
	//配置USART3
	USART_InitTypeDef USART_InitStruct;
	USART_InitStruct.USART_WordLength = USART_WordLength_8b;
	USART_InitStruct.USART_StopBits = USART_StopBits_1;
	USART_InitStruct.USART_BaudRate = ulBaudRate;
	USART_InitStruct.USART_Parity = USART_Parity_No;
	USART_InitStruct.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
	USART_InitStruct.USART_Mode = USART_Mode_Rx|USART_Mode_Tx;
	USART_Init(USART3,&USART_InitStruct);
	USART_Cmd(USART3,ENABLE);
	
	//配置中断
	NVIC_InitTypeDef NVIC_InitStruct;
	NVIC_InitStruct.NVIC_IRQChannelCmd = ENABLE;
	NVIC_InitStruct.NVIC_IRQChannelPreemptionPriority = 1;
	NVIC_InitStruct.NVIC_IRQChannelSubPriority = 1;
	NVIC_InitStruct.NVIC_IRQChannel = USART3_IRQn;
	NVIC_Init(&NVIC_InitStruct);
  return TRUE;
}

BOOL
xMBPortSerialPutByte( CHAR ucByte )
{
    USART_SendData(USART3,ucByte);
    return TRUE;
}

BOOL
xMBPortSerialGetByte( CHAR * pucByte )
{
    *pucByte = USART_ReceiveData(USART3);
    return TRUE;
}

/* Create an interrupt handler for the transmit buffer empty interrupt
 * (or an equivalent) for your target processor. This function should then
 * call pxMBFrameCBTransmitterEmpty( ) which tells the protocol stack that
 * a new character can be sent. The protocol stack will then call 
 * xMBPortSerialPutByte( ) to send the character.
 */
static void prvvUARTTxReadyISR( void )
{
    pxMBFrameCBTransmitterEmpty(  );
}

/* Create an interrupt handler for the receive interrupt for your target
 * processor. This function should then call pxMBFrameCBByteReceived( ). The
 * protocol stack will then call xMBPortSerialGetByte( ) to retrieve the
 * character.
 */
static void prvvUARTRxISR( void )
{
    pxMBFrameCBByteReceived(  );
}

void USART3_IRQHandler(void)
{
	if(USART_GetITStatus(USART3, USART_IT_RXNE) == SET)
	{
		prvvUARTRxISR();  
		USART_ClearITPendingBit(USART3, USART_IT_RXNE);   
	}
	if(USART_GetITStatus(USART3, USART_IT_TC) == SET)
	{
		prvvUARTTxReadyISR();
		USART_ClearITPendingBit(USART3, USART_IT_TC);
	}
}

porttimer.c

本文件夹是初始化定时器,实现帧结束的截取。

xMBPortTimersInit初始化定时器,需要将计数间隔设定为50us(设时钟72MHz,这里将分频系数设置到3600-1,实现50us计时),定时周期按参数设置,并使能更新中断。这里我使用TIM1。

BOOL
xMBPortTimersInit( USHORT usTim1Timerout50us )
{
	RCC_APB2PeriphClockCmd(RCC_APB2ENR_TIM1EN,ENABLE);
	TIM_TimeBaseInitTypeDef tbit;
	tbit.TIM_Prescaler = 3600-1;
	tbit.TIM_Period = usTim1Timerout50us;
	tbit.TIM_ClockDivision = TIM_CKD_DIV1;
	tbit.TIM_CounterMode = TIM_CounterMode_Up;
	tbit.TIM_RepetitionCounter = 0;
	TIM_TimeBaseInit(TIM1,&tbit);
	TIM_ClearFlag(TIM1,TIM_IT_Update);
	
	NVIC_InitTypeDef nvic_inittypeddef;
	nvic_inittypeddef.NVIC_IRQChannel = TIM1_UP_IRQn;
	nvic_inittypeddef.NVIC_IRQChannelCmd = ENABLE;
	nvic_inittypeddef.NVIC_IRQChannelPreemptionPriority = 0;
	nvic_inittypeddef.NVIC_IRQChannelSubPriority = 3;
	NVIC_Init(&nvic_inittypeddef);
 	return TRUE;
}

vMBPortTimersEnable与vMBPortTimersDisable函数进行定时器的使能与失能(去掉inline)。并写对应的中断函数,当中断触发时调用FreeModbus写好的处理函数。

void
vMBPortTimersEnable(  )
{
		TIM_ClearITPendingBit(TIM1, TIM_IT_Update);
		TIM_ITConfig(TIM1, TIM_IT_Update, ENABLE);
		TIM_SetCounter(TIM1, 0);
		TIM_Cmd(TIM1, ENABLE);
    /* Enable the timer with the timeout passed to xMBPortTimersInit( ) */
}

void
vMBPortTimersDisable(  )
{
		TIM_ClearITPendingBit(TIM1, TIM_IT_Update);
		TIM_ITConfig(TIM1, TIM_IT_Update, DISABLE);
		TIM_SetCounter(TIM1, 0);
		TIM_Cmd(TIM1, DISABLE);
    /* Disable any pending timers. */
}

void TIM1_UP_IRQHandler(void)
{
	if (TIM_GetITStatus(TIM1, TIM_IT_Update) != RESET)
	{
		prvvTIMERExpiredISR();
		TIM_ClearITPendingBit(TIM1, TIM_IT_Update);
	}
}

以下是本文件全部内容:

/* ----------------------- Platform includes --------------------------------*/
#include "port.h"
#include "stm32f10x.h"
/* ----------------------- Modbus includes ----------------------------------*/
#include "mb.h"
#include "mbport.h"

/* ----------------------- static functions ---------------------------------*/
static void prvvTIMERExpiredISR( void );

/* ----------------------- Start implementation -----------------------------*/
BOOL
xMBPortTimersInit( USHORT usTim1Timerout50us )
{
	RCC_APB2PeriphClockCmd(RCC_APB2ENR_TIM1EN,ENABLE);
	TIM_TimeBaseInitTypeDef tbit;
	tbit.TIM_Prescaler = 3600-1;
	tbit.TIM_Period = usTim1Timerout50us;
	tbit.TIM_ClockDivision = TIM_CKD_DIV1;
	tbit.TIM_CounterMode = TIM_CounterMode_Up;
	tbit.TIM_RepetitionCounter = 0;
	TIM_TimeBaseInit(TIM1,&tbit);
	TIM_ClearFlag(TIM1,TIM_IT_Update);
	
	NVIC_InitTypeDef nvic_inittypeddef;
	nvic_inittypeddef.NVIC_IRQChannel = TIM1_UP_IRQn;
	nvic_inittypeddef.NVIC_IRQChannelCmd = ENABLE;
	nvic_inittypeddef.NVIC_IRQChannelPreemptionPriority = 0;
	nvic_inittypeddef.NVIC_IRQChannelSubPriority = 3;
	NVIC_Init(&nvic_inittypeddef);
 	return TRUE;
}


void
vMBPortTimersEnable(  )
{
		TIM_ClearITPendingBit(TIM1, TIM_IT_Update);
		TIM_ITConfig(TIM1, TIM_IT_Update, ENABLE);
		TIM_SetCounter(TIM1, 0);
		TIM_Cmd(TIM1, ENABLE);
    /* Enable the timer with the timeout passed to xMBPortTimersInit( ) */
}

void
vMBPortTimersDisable(  )
{
		TIM_ClearITPendingBit(TIM1, TIM_IT_Update);
		TIM_ITConfig(TIM1, TIM_IT_Update, DISABLE);
		TIM_SetCounter(TIM1, 0);
		TIM_Cmd(TIM1, DISABLE);
    /* Disable any pending timers. */
}

/* Create an ISR which is called whenever the timer has expired. This function
 * must then call pxMBPortCBTimerExpired( ) to notify the protocol stack that
 * the timer has expired.
 */
static void prvvTIMERExpiredISR( void )
{
    ( void )pxMBPortCBTimerExpired(  );
}

void TIM1_UP_IRQHandler(void)
{
	if (TIM_GetITStatus(TIM1, TIM_IT_Update) != RESET)
	{
		prvvTIMERExpiredISR();
		TIM_ClearITPendingBit(TIM1, TIM_IT_Update);
	}
}

mbconfig.h

第49行将宏MB_ASCII_ENABLED失能,因为我们这里只使用RTU。
这个文件可以选择使能Modbus功能码函数,实现功能裁剪。

此时进行编译,会发现会报以下错误:
四种数据类型(线圈、离散量、输入寄存器、保持寄存器)的操作函数与断言的定义没有实现,所以需要继续实现它们。

port.c

这个文件是自己新建的,我们在这个文件实现上述缺少的函数。

如何实现这些函数?同样可以参考Demo文件夹中的示例。例如Demo->MSP430->demo.c中的内容,这一部分可以复制到port.c中:

#include "mb.h"
#define REG_INPUT_START   0
#define REG_INPUT_NREGS   10
#define REG_HOLDING_START 0
#define REG_HOLDING_NREGS 10

static USHORT   usRegInputStart = REG_INPUT_START;
static USHORT   usRegInputBuf[REG_INPUT_NREGS];
static USHORT   usRegHoldingStart = REG_HOLDING_START;
static USHORT   usRegHoldingBuf[REG_HOLDING_NREGS];

eMBErrorCode
eMBRegInputCB( UCHAR * pucRegBuffer, USHORT usAddress, USHORT usNRegs )
{
    eMBErrorCode    eStatus = MB_ENOERR;
    int             iRegIndex;

    if( ( (int16_t)usAddress >= REG_INPUT_START )
        && ( usAddress + usNRegs <= REG_INPUT_START + REG_INPUT_NREGS ) )
    {
        iRegIndex = ( int )( usAddress - usRegInputStart );
        while( usNRegs > 0 )
        {
            *pucRegBuffer++ = ( unsigned char )( usRegInputBuf[iRegIndex] >> 8 );
            *pucRegBuffer++ = ( unsigned char )( usRegInputBuf[iRegIndex] & 0xFF );
            iRegIndex++;
            usNRegs--;
        }
    }
    else
    {
        eStatus = MB_ENOREG;
    }

    return eStatus;
}


eMBErrorCode
eMBRegHoldingCB( UCHAR * pucRegBuffer, USHORT usAddress, USHORT usNRegs, eMBRegisterMode eMode )
{
    eMBErrorCode    eStatus = MB_ENOERR;
    int             iRegIndex;

    if( ( (int16_t)usAddress >= REG_HOLDING_START ) &&
        ( usAddress + usNRegs <= REG_HOLDING_START + REG_HOLDING_NREGS ) )
    {
        iRegIndex = ( int )( usAddress - usRegHoldingStart );
        switch ( eMode )
        {
            /* Pass current register values to the protocol stack. */
        case MB_REG_READ:
            while( usNRegs > 0 )
            {
                *pucRegBuffer++ = ( unsigned char )( usRegHoldingBuf[iRegIndex] >> 8 );
                *pucRegBuffer++ = ( unsigned char )( usRegHoldingBuf[iRegIndex] & 0xFF );
                iRegIndex++;
                usNRegs--;
            }
            break;

            /* Update current register values with new values from the
             * protocol stack. */
        case MB_REG_WRITE:
            while( usNRegs > 0 )
            {
                usRegHoldingBuf[iRegIndex] = *pucRegBuffer++ << 8;
                usRegHoldingBuf[iRegIndex] |= *pucRegBuffer++;
                iRegIndex++;
                usNRegs--;
            }
        }
    }
    else
    {
        eStatus = MB_ENOREG;
    }
    return eStatus;
}

前面的数组usRegInputBuf与usRegHoldingBuf就是操作的输入寄存器与保持寄存器,而REG_INPUT_START与REG_HOLDING_START是这两类寄存器的起始地址。当从机收到特定的功能码时,会转为对这些数据变量的操作。

下面的eMBRegInputCB与eMBRegHoldingCB就是输入寄存器与保持寄存器对应的处理函数。在Modbus协议层面来讲就是实现了对应的功能码。虽然目前看不懂具体实现,但是只需要贴进来用即可。

下面打开源码Demo->STR71X->excolis.c与exdisc.c,线圈量与离散量的处理函数就在里面。与寄存器类似,将它们复制到port.c。

#include "mbutils.h"
#define REG_COILS_START     0
#define REG_COILS_SIZE      16
static unsigned char ucRegCoilsBuf[REG_COILS_SIZE / 8];


eMBErrorCode
eMBRegCoilsCB( UCHAR * pucRegBuffer, USHORT usAddress, USHORT usNCoils,
               eMBRegisterMode eMode )
{
    eMBErrorCode    eStatus = MB_ENOERR;
    int             iNCoils = ( int )usNCoils;
    unsigned short  usBitOffset;

    /* Check if we have registers mapped at this block. */
    if( ( (int16_t)usAddress >= REG_COILS_START ) &&
        ( usAddress + usNCoils <= REG_COILS_START + REG_COILS_SIZE ) )
    {
        usBitOffset = ( unsigned short )( usAddress - REG_COILS_START );
        switch ( eMode )
        {
                /* Read current values and pass to protocol stack. */
            case MB_REG_READ:
                while( iNCoils > 0 )
                {
                    *pucRegBuffer++ =
                        xMBUtilGetBits( ucRegCoilsBuf, usBitOffset,
                                        ( unsigned char )( iNCoils >
                                                           8 ? 8 :
                                                           iNCoils ) );
                    iNCoils -= 8;
                    usBitOffset += 8;
                }
                break;

                /* Update current register values. */
            case MB_REG_WRITE:
                while( iNCoils > 0 )
                {
                    xMBUtilSetBits( ucRegCoilsBuf, usBitOffset, 
                                    ( unsigned char )( iNCoils > 8 ? 8 : iNCoils ),
                                    *pucRegBuffer++ );
                    iNCoils -= 8;
                    usBitOffset += 8;
                }
                break;
        }

    }
    else
    {
        eStatus = MB_ENOREG;
    }
    return eStatus;
}


#define REG_DISC_START     0
#define REG_DISC_SIZE      16
static unsigned char ucRegDiscBuf[REG_DISC_SIZE / 8] = { 0, 0 };

eMBErrorCode
eMBRegDiscreteCB( UCHAR * pucRegBuffer, USHORT usAddress, USHORT usNDiscrete )
{
    eMBErrorCode    eStatus = MB_ENOERR;
    short           iNDiscrete = ( short )usNDiscrete;
    unsigned short  usBitOffset;

    /* Check if we have registers mapped at this block. */
    if( ( (int16_t)usAddress >= REG_DISC_START ) &&
        ( usAddress + usNDiscrete <= REG_DISC_START + REG_DISC_SIZE ) )
    {
        usBitOffset = ( unsigned short )( usAddress - REG_DISC_START );
        while( iNDiscrete > 0 )
        {
            *pucRegBuffer++ =
                xMBUtilGetBits( ucRegDiscBuf, usBitOffset,
                                ( unsigned char )( iNDiscrete >
                                                   8 ? 8 : iNDiscrete ) );
            iNDiscrete -= 8;
            usBitOffset += 8;
        }
    }
    else
    {
        eStatus = MB_ENOREG;
    }
    return eStatus;
}

注意,开关量与离散量都是位数据,因此数组长度会除以8。

然后再给断言函数加上,整个port.c就写好了。

void __aeabi_assert(const char * x1, const char * x2, int x3)
{
	
}

实现上述函数与数据,就实现了Modbus绝大多数功能码。

mbrtu.c的eMBRTUSend函数

第213行后面添加代码:

xMBPortSerialPutByte( ( CHAR )*pucSndBufferCur );
pucSndBufferCur++;  /* next byte in sendbuffer. */
usSndBufferCount--;

更新后的eMBRTUSend函数:

eMBErrorCode
eMBRTUSend( UCHAR ucSlaveAddress, const UCHAR * pucFrame, USHORT usLength )
{
    eMBErrorCode    eStatus = MB_ENOERR;
    USHORT          usCRC16;

    ENTER_CRITICAL_SECTION(  );

    /* Check if the receiver is still in idle state. If not we where to
     * slow with processing the received frame and the master sent another
     * frame on the network. We have to abort sending the frame.
     */
    if( eRcvState == STATE_RX_IDLE )
    {
        /* First byte before the Modbus-PDU is the slave address. */
        pucSndBufferCur = ( UCHAR * ) pucFrame - 1;
        usSndBufferCount = 1;

        /* Now copy the Modbus-PDU into the Modbus-Serial-Line-PDU. */
        pucSndBufferCur[MB_SER_PDU_ADDR_OFF] = ucSlaveAddress;
        usSndBufferCount += usLength;

        /* Calculate CRC16 checksum for Modbus-Serial-Line-PDU. */
        usCRC16 = usMBCRC16( ( UCHAR * ) pucSndBufferCur, usSndBufferCount );
        ucRTUBuf[usSndBufferCount++] = ( UCHAR )( usCRC16 & 0xFF );
        ucRTUBuf[usSndBufferCount++] = ( UCHAR )( usCRC16 >> 8 );

        /* Activate the transmitter. */
        eSndState = STATE_TX_XMIT;
			
				xMBPortSerialPutByte((CHAR)*pucSndBufferCur);
        pucSndBufferCur++;
        usSndBufferCount--;
			
        vMBPortSerialEnable( FALSE, TRUE );
    }
    else
    {
        eStatus = MB_EIO;
    }
    EXIT_CRITICAL_SECTION(  );
    return eStatus;
}

mbfunccoils.c,mbfuncdisc.c,mbfuncholding.c,mbfuncinput.c

首先去掉所有的usRegAddress++,否则实际操作会比期望地址大一。

然后mbfuncholding.c第185行,添加一个或负号:

usRegCount |= ( USHORT )( pucFrame[MB_PDU_FUNC_READ_REGCNT_OFF + 1] );

至此,代码修改完成,编译应该没有error了。

测试

main文件

#include "stm32f10x.h"
#include "mb.h"
int main(void){
	eMBInit(MB_RTU, 0X01, 3, 9600, MB_PAR_NONE);//初始化FreeModbus
    eMBEnable();//FreeModbus使能
    while (1)
    {
        eMBPoll();//在while (1)循环调用eMBPoll()
    }
}

eMBInit进行初始化,其中第一个参数表示协议,第二个参数是从机地址,后面三个是初始化串口那个函数的参数,可以跳转到那里进行对照(这里配置为串口3,波特率9600,不校验)

eMBEnable()启动FreeModbus后,不断调用eMBPoll()即可。

port.c

这里我们修改一下各个位数据与寄存器的初始值,方便观察结果。

static USHORT   usRegInputBuf[REG_INPUT_NREGS] = {0,1,2,3,4,5,6,7,8,9};
static USHORT   usRegHoldingBuf[REG_HOLDING_NREGS] = {10,11,12,13,14,15,16,17,18,19};
static unsigned char ucRegCoilsBuf[REG_COILS_SIZE / 8] = {0x12,0x34};
static unsigned char ucRegDiscBuf[REG_DISC_SIZE / 8] = {0x56,0x78};

使用ModbusPoll连接,看到可以正常读出数据:

作者:终极末影龙

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