hello.
i was try to implement modbusTCP on STM32F7
my STM32F7 is modbus slave and my PC is modbus master for simulation.
it was work but have one question:
my modbus slave will store data to all slave(1-248), in normally, i should be store data to own slave only.
How to fix that?
i use freeRTOS to listen TCP
void StartDefaultTask(void const * argument)
{
/* init code for LWIP */
MX_LWIP_Init();
/* USER CODE BEGIN StartDefaultTask */
eMBTCPInit(0);
eMBEnable();
/* Infinite loop */
for(;;)
{
eMBPoll();
osDelay(1);
__NOP();
}
/* USER CODE END StartDefaultTask */
}eMBErrorCode
eMBPoll( void )
{
/* Tx & Rx use same frame(ucMBFrame) as buffer
* the ucMBFrame is only PDU section, no MBAP information
* --------PBU--------
* ucMBFrame[0]: FunctionCode
* ucMBFrame[1]: Register address(MSB)
* ucMBFrame[2]: Register address(LSB)
* ucMBFrame[3]: Register number(MSB)
* ucMBFrame[4]: Register number(LSB)
*
* ex. receive frame from modbus_poll
* Tx:000128-E3 B5 00 00 00 06 0A 03 00 00 00 10 (hex)
* ucMBFrame[0]: 03 (dec)
* ucMBFrame[1]: 00
* ucMBFrame[2]: 00
* ucMBFrame[3]: 00
* ucMBFrame[4]: 16
*/
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. */
if( xMBPortEventGet( &eEvent ) == TRUE )
{
switch ( eEvent )
{
case EV_READY:
break;
case EV_FRAME_RECEIVED:
//receive frame at ucMBFrame
eStatus = peMBFrameReceiveCur( &ucRcvAddress, &ucMBFrame, &usLength );
if( eStatus == MB_ENOERR )
{
/* Check if the frame is for us. If not ignore the frame. */
if( ( ucRcvAddress == ucMBAddress ) || ( ucRcvAddress == MB_ADDRESS_BROADCAST ) )
{
( 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 )
{
//entry eMBFuncReadHoldingRegister function
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;
}
eStatus = peMBFrameSendCur( ucMBAddress, ucMBFrame, usLength );
}
break;
case EV_FRAME_SENT:
break;
}
}
return MB_ENOERR;
}eMBException
eMBFuncReadHoldingRegister( UCHAR * pucFrame, USHORT * usLen )
{
USHORT usRegAddress;
USHORT usRegCount;
UCHAR *pucFrameCur;
eMBException eStatus = MB_EX_NONE;
eMBErrorCode eRegStatus;
if( *usLen == ( MB_PDU_FUNC_READ_SIZE + MB_PDU_SIZE_MIN ) )
{
usRegAddress = ( USHORT )( pucFrame[MB_PDU_FUNC_READ_ADDR_OFF] << 8 );
usRegAddress |= ( USHORT )( pucFrame[MB_PDU_FUNC_READ_ADDR_OFF + 1] );
usRegAddress++;
//master query quantity
usRegCount = ( USHORT )( pucFrame[MB_PDU_FUNC_READ_REGCNT_OFF] << 8 );
usRegCount = ( USHORT )( pucFrame[MB_PDU_FUNC_READ_REGCNT_OFF + 1] );
__NOP();
/* Check if the number of registers to read is valid. If not
* return Modbus illegal data value exception.
*/
if( ( usRegCount >= 1 ) && ( usRegCount <= MB_PDU_FUNC_READ_REGCNT_MAX ) )
{
/* Set the current PDU data pointer to the beginning. */
pucFrameCur = &pucFrame[MB_PDU_FUNC_OFF];
*usLen = MB_PDU_FUNC_OFF;
/* First byte contains the function code. */
*pucFrameCur++ = MB_FUNC_READ_HOLDING_REGISTER;
*usLen += 1;
/* Second byte in the response contain the number of bytes. */
*pucFrameCur++ = ( UCHAR ) ( usRegCount * 2 );
*usLen += 1;
/* Make callback to fill the buffer. */
eRegStatus = eMBRegHoldingCB( pucFrameCur, usRegAddress, usRegCount, MB_REG_READ );
/* If an error occured convert it into a Modbus exception. */
if( eRegStatus != MB_ENOERR )
{
eStatus = prveMBError2Exception( eRegStatus );
}
else
{
*usLen += usRegCount * 2;
}
}
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;
}my project git: https://github.com/alien18331/ST_ModbusTCP
