基于STM32F767通过STM32CubeMX实现ModbusTCP

1万 · 2021-8-4 16:47

文件解析

按照一下方式加入文件（大神可按自己的习惯操作）

文件导入后不要忘记加入相应头文件：点击魔法棒 > 进入C/C++选项卡，点击Include Paths后的 … 按钮，将下图的Modbus相关目录加入

1万 · 2021-8-4 16:48

接收到的数据位置解析
本次主要讲读保持寄存器功能，所以主要解释的文件为上图middlewares/Modbus目录下的mbfuncholding.c文件，以下附上该文件代码

/* ----------------------- 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"

/* ----------------------- Defines ------------------------------------------*/
#define MB_PDU_FUNC_READ_ADDR_OFF             ( MB_PDU_DATA_OFF + 0)
#define MB_PDU_FUNC_READ_REGCNT_OFF          ( MB_PDU_DATA_OFF + 2 )
#define MB_PDU_FUNC_READ_SIZE                ( 4 )
#define MB_PDU_FUNC_READ_REGCNT_MAX          ( 0x007D )

#define MB_PDU_FUNC_WRITE_ADDR_OFF             ( MB_PDU_DATA_OFF + 0)
#define MB_PDU_FUNC_WRITE_VALUE_OFF          ( MB_PDU_DATA_OFF + 2 )
#define MB_PDU_FUNC_WRITE_SIZE                ( 4 )

#define MB_PDU_FUNC_WRITE_MUL_ADDR_OFF       ( MB_PDU_DATA_OFF + 0 )
#define MB_PDU_FUNC_WRITE_MUL_REGCNT_OFF       ( MB_PDU_DATA_OFF + 2 )
#define MB_PDU_FUNC_WRITE_MUL_BYTECNT_OFF    ( MB_PDU_DATA_OFF + 4 )
#define MB_PDU_FUNC_WRITE_MUL_VALUES_OFF       ( MB_PDU_DATA_OFF + 5 )
#define MB_PDU_FUNC_WRITE_MUL_SIZE_MIN       ( 5 )
#define MB_PDU_FUNC_WRITE_MUL_REGCNT_MAX       ( 0x0078 )

#define MB_PDU_FUNC_READWRITE_READ_ADDR_OFF    ( MB_PDU_DATA_OFF + 0 )
#define MB_PDU_FUNC_READWRITE_READ_REGCNT_OFF ( MB_PDU_DATA_OFF + 2 )
#define MB_PDU_FUNC_READWRITE_WRITE_ADDR_OFF ( MB_PDU_DATA_OFF + 4 )
#define MB_PDU_FUNC_READWRITE_WRITE_REGCNT_OFF  ( MB_PDU_DATA_OFF + 6 )
#define MB_PDU_FUNC_READWRITE_BYTECNT_OFF    ( MB_PDU_DATA_OFF + 8 )
#define MB_PDU_FUNC_READWRITE_WRITE_VALUES_OFF  ( MB_PDU_DATA_OFF + 9 )
#define MB_PDU_FUNC_READWRITE_SIZE_MIN       ( 9 )

/* ----------------------- Static functions ---------------------------------*/
eMBException prveMBError2Exception( eMBErrorCode eErrorCode );

/* ----------------------- Start implementation -----------------------------*/

以上为ModbusTCP关于操作保持寄存器对收到代码的对应位置的代码作用记录；

1万 · 2021-8-4 16:48

写一位保持寄存器
#if MB_FUNC_WRITE_HOLDING_ENABLED > 0

eMBException
eMBFuncWriteHoldingRegister( UCHAR * pucFrame, USHORT * usLen )
{
USHORT       usRegAddress;
eMBException eStatus = MB_EX_NONE;
eMBErrorCode eRegStatus;

if( *usLen == ( MB_PDU_FUNC_WRITE_SIZE + MB_PDU_SIZE_MIN ) )
{
      usRegAddress = ( USHORT )( pucFrame[MB_PDU_FUNC_WRITE_ADDR_OFF] << 8 );
      usRegAddress |= ( USHORT )( pucFrame[MB_PDU_FUNC_WRITE_ADDR_OFF + 1] );
      usRegAddress++;

      /* Make callback to update the value. */
      eRegStatus = eMBRegHoldingCB( &pucFrame[MB_PDU_FUNC_WRITE_VALUE_OFF],
                                    usRegAddress, 1, MB_REG_WRITE );

      /* If an error occured convert it into a Modbus exception. */
      if( eRegStatus != MB_ENOERR )
      {
         eStatus = prveMBError2Exception( eRegStatus );
      }
}
else
{
      /* Can't be a valid request because the length is incorrect. */
      eStatus = MB_EX_ILLEGAL_DATA_VALUE;
}
return eStatus;
}
#endif

该段是写一位保持寄存器的具体代码；

1万 · 2021-8-4 16:48

写多位保持寄存器代码
#if MB_FUNC_WRITE_MULTIPLE_HOLDING_ENABLED > 0
eMBException
eMBFuncWriteMultipleHoldingRegister( UCHAR * pucFrame, USHORT * usLen )
{
USHORT       usRegAddress;
USHORT       usRegCount;
UCHAR          ucRegByteCount;

eMBException eStatus = MB_EX_NONE;
eMBErrorCode eRegStatus;

if( *usLen >= ( MB_PDU_FUNC_WRITE_MUL_SIZE_MIN + MB_PDU_SIZE_MIN ) )
{
      usRegAddress = ( USHORT )( pucFrame[MB_PDU_FUNC_WRITE_MUL_ADDR_OFF] << 8 );
      usRegAddress |= ( USHORT )( pucFrame[MB_PDU_FUNC_WRITE_MUL_ADDR_OFF + 1] );
      usRegAddress++;

      usRegCount = ( USHORT )( pucFrame[MB_PDU_FUNC_WRITE_MUL_REGCNT_OFF] << 8 );
      usRegCount |= ( USHORT )( pucFrame[MB_PDU_FUNC_WRITE_MUL_REGCNT_OFF + 1] );

      ucRegByteCount = pucFrame[MB_PDU_FUNC_WRITE_MUL_BYTECNT_OFF];

      if( ( usRegCount >= 1 ) &&
         ( usRegCount <= MB_PDU_FUNC_WRITE_MUL_REGCNT_MAX ) &&
         ( ucRegByteCount == ( UCHAR ) ( 2 * usRegCount ) ) )
      {
         /* Make callback to update the register values. */
         eRegStatus =
            eMBRegHoldingCB( &pucFrame[MB_PDU_FUNC_WRITE_MUL_VALUES_OFF],
                              usRegAddress, usRegCount, MB_REG_WRITE );

         /* If an error occured convert it into a Modbus exception. */
         if( eRegStatus != MB_ENOERR )
         {
            eStatus = prveMBError2Exception( eRegStatus );
         }
         else
         {
            /* The response contains the function code, the starting
               * address and the quantity of registers. We reuse the
               * old values in the buffer because they are still valid.
               */
            *usLen = MB_PDU_FUNC_WRITE_MUL_BYTECNT_OFF;
         }
      }
      else
      {
         eStatus = MB_EX_ILLEGAL_DATA_VALUE;
      }
}
else
{
      /* Can't be a valid request because the length is incorrect. */
      eStatus = MB_EX_ILLEGAL_DATA_VALUE;
}
return eStatus;
}
#endif

1万 · 2021-8-4 16:49

TCP服务器建立
由于ModbusTCP是以TCP协议为基础的Modbus协议，所以接收到的数据是以TCP协议包内嵌Modbus协议包来完成的，所以就需要对包进行分层解析，首先解析了TCP层相应数据后再解析Modbus层数据，所以首先我们的代码中会有一段建立TCP服务器的代码，其代码在middlewares/Modbus/port目录下的porttcp.c文件，代码如下

xMBTCPPortInit( USHORT usTCPPort )
{
struct tcp_pcb *pxPCBListenNew, *pxPCBListenOld;
BOOL          bOkay = FALSE;
USHORT       usPort;

if( usTCPPort == 0 )
{
      usPort = MB_TCP_DEFAULT_PORT;
}
else
{
      usPort = ( USHORT ) usTCPPort;
}

if( ( pxPCBListenNew = pxPCBListenOld = tcp_new(  ) ) == NULL ) //建立TCP服务器
{
      /* Can't create TCP socket. */
      bOkay = FALSE;
}
else if( tcp_bind( pxPCBListenNew, IP_ADDR_ANY, ( u16_t ) usPort ) != ERR_OK )//TCP服务器建立成功后进入监听状态
{
      /* Bind failed - Maybe illegal port value or in use. */
      ( void )tcp_close( pxPCBListenOld );
      bOkay = FALSE;
}
else if( ( pxPCBListenNew = tcp_listen( pxPCBListenNew ) ) == NULL )
{
      ( void )tcp_close( pxPCBListenOld );
      bOkay = FALSE;
}
else
{
      /* Register callback function for new clients. */
      tcp_accept( pxPCBListenNew, prvxMBTCPPortAccept );

      /* Everything okay. Set global variable. */
      pxPCBListen = pxPCBListenNew;

#ifdef MB_TCP_DEBUG
      vMBPortLog( MB_LOG_DEBUG, "MBTCP-ACCEPT", "Protocol stack ready.\r\n" );
#endif
}
bOkay = TRUE;
return bOkay;
}

以上代码为TCP服务器的建立过程，ModbusTCP默认端口为502端口，此处无需更改；

1万 · 2021-8-4 16:49

本帖最后由 wakayi 于 2021-8-4 16:51 编辑

收到数据需要做出的动作
以上讲述了ModbusTCP从建立TCP服务器到对收到的代码进行解析的过程，接下来就要进行收到数据的操作过程，其代码位于middlewares/Modbus目录下的modbusCB.c文件中，代码如下

uint16_t DB_R[88];                      //保持寄存器数值存储空间
uint16_t DB_C[88];                      //线圈寄存器数值存储空间
uint16_t DB_I[88];                      //输入流数值存储空间
uint16_t DB_D[88];                      //离散量数值存储空间
eMBErrorCode
eMBRegHoldingCB( UCHAR * pucRegBuffer, USHORT usAddress, USHORT usNRegs, eMBRegisterMode eMode )
{
      eMBErrorCode eStatus = MB_ENOERR;
      static uint8_t flag = 0;
      int i=0;
      flag ^= 1;
      /*the following code is just for the testing the function of reading register       */
      /**********************************读保持寄存器************************************/
      if(eMode==MB_REG_READ)
      {
            DB_R[0]=0x1001;
            DB_R[1]=0x2001;
            DB_R[2]=0x3001;
            DB_R[3]=0x4001;
            for(i=0;i<usNRegs;i++)
                     {
                              *pucRegBuffer=DB_R[i+usAddress-1]>>8;
                              pucRegBuffer++;
                              *pucRegBuffer=DB_R[i+usAddress-1]&0xff;
                              pucRegBuffer++;
                     }
      }
      /***************************************GAS********************************************/
      /*********************************写保持寄存器*************************************/
      if(eMode==MB_REG_WRITE)
      {
            for(i=0;i<usNRegs;i++)
                     {
                              DB_R[i+usAddress-1]=*pucRegBuffer>>8;
                              pucRegBuffer++;
                              DB_R[i+usAddress-1]=*pucRegBuffer&0xff;
                              pucRegBuffer++;
                     }
      }
      /**************************************GAS*****************************************/
return eStatus;
}

上述代码主要功能在读写保持寄存器，开辟了4个存储空间用于存放保持寄存器数值、线圈寄存器数值、输入量数值和离散量数值，为测试通讯正常，我提前将数值写入保持寄存器数值存储空间的0~3空间分别写入值，方便读取

在上述操作完成后，在主函数中加入:

eMBTCPInit( 0 ); eMBEnable();

之后再主函数的主循环加入：

eMBPoll();

即可不断运行Modbus的数据操作。

1万 · 2021-8-4 16:52

测试部分
在上述文件导入工程后编译下载到开发板，用网线连接开发版和计算机。在计算机下载安装ModbusTool工具（可在GITHUB上搜索下载），该代码实现的时从站（服务器）功能，所以打开ModbusTool工具的MBMaster (Active)，在确保可以ping通开发板的情况下按照下图所示设置，IP写为开发板地址，设置完成后点击Connect，在下方黑框提示连接成功即可；若链接失败，检查网络情况或重启开发板；

完成连接后点击Read holding即可在0~3所在空格读取到之前设置在DB_R数组中的值，如图

完成以上操作后说明ModbusTCP协议已打通，也可以读取到Modbus数据，接下来的工作就是通过接收到的数据控制硬件动作，由大家自由发挥，希望大家能多多指点。

基于STM32F767通过STM32CubeMX实现ModbusTCP

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