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esp-idf/components/freemodbus/modbus/ascii/mbascii.c

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/*
* FreeModbus Libary: A portable Modbus implementation for Modbus ASCII/RTU.
* Copyright (c) 2006 Christian Walter <wolti@sil.at>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* File: $Id: mbascii.c,v 1.17 2010/06/06 13:47:07 wolti Exp $
*/
/* ----------------------- System includes ----------------------------------*/
#include "stdlib.h"
#include "string.h"
/* ----------------------- Platform includes --------------------------------*/
#include "port.h"
/* ----------------------- Modbus includes ----------------------------------*/
#include "mb.h"
#include "mbconfig.h"
#include "mbascii.h"
#include "mbframe.h"
#include "mbcrc.h"
#include "mbport.h"
#if MB_SLAVE_ASCII_ENABLED > 0
/* ----------------------- Defines ------------------------------------------*/
#define MB_ASCII_DEFAULT_CR '\r' /*!< Default CR character for Modbus ASCII. */
#define MB_ASCII_DEFAULT_LF '\n' /*!< Default LF character for Modbus ASCII. */
#define MB_SER_PDU_SIZE_MIN 3 /*!< Minimum size of a Modbus ASCII frame. */
#define MB_SER_PDU_SIZE_MAX 256 /*!< Maximum size of a Modbus ASCII frame. */
#define MB_SER_PDU_SIZE_LRC 1 /*!< Size of LRC field in PDU. */
#define MB_SER_PDU_ADDR_OFF 0 /*!< Offset of slave address in Ser-PDU. */
#define MB_SER_PDU_PDU_OFF 1 /*!< Offset of Modbus-PDU in Ser-PDU. */
/* ----------------------- Type definitions ---------------------------------*/
typedef enum
{
STATE_RX_IDLE, /*!< Receiver is in idle state. */
STATE_RX_RCV, /*!< Frame is beeing received. */
STATE_RX_WAIT_EOF /*!< Wait for End of Frame. */
} eMBRcvState;
typedef enum
{
STATE_TX_IDLE, /*!< Transmitter is in idle state. */
STATE_TX_START, /*!< Starting transmission (':' sent). */
STATE_TX_DATA, /*!< Sending of data (Address, Data, LRC). */
STATE_TX_END, /*!< End of transmission. */
STATE_TX_NOTIFY /*!< Notify sender that the frame has been sent. */
} eMBSndState;
typedef enum
{
BYTE_HIGH_NIBBLE, /*!< Character for high nibble of byte. */
BYTE_LOW_NIBBLE /*!< Character for low nibble of byte. */
} eMBBytePos;
/* ----------------------- Static functions ---------------------------------*/
static UCHAR prvucMBCHAR2BIN( UCHAR ucCharacter );
static UCHAR prvucMBBIN2CHAR( UCHAR ucByte );
static UCHAR prvucMBLRC( UCHAR * pucFrame, USHORT usLen );
/* ----------------------- Static variables ---------------------------------*/
static volatile eMBSndState eSndState;
static volatile eMBRcvState eRcvState;
/* We reuse the Modbus RTU buffer because only one buffer is needed and the
* RTU buffer is bigger. */
extern volatile UCHAR ucRTUBuf[];
static volatile UCHAR *ucASCIIBuf = ucRTUBuf;
static volatile USHORT usRcvBufferPos;
static volatile eMBBytePos eBytePos;
static volatile UCHAR *pucSndBufferCur;
static volatile USHORT usSndBufferCount;
static volatile UCHAR ucLRC;
static volatile UCHAR ucMBLFCharacter;
/* ----------------------- Start implementation -----------------------------*/
eMBErrorCode
eMBASCIIInit( UCHAR ucSlaveAddress, UCHAR ucPort, ULONG ulBaudRate, eMBParity eParity )
{
eMBErrorCode eStatus = MB_ENOERR;
( void )ucSlaveAddress;
ENTER_CRITICAL_SECTION( );
ucMBLFCharacter = MB_ASCII_DEFAULT_LF;
if( xMBPortSerialInit( ucPort, ulBaudRate, 7, eParity ) != TRUE )
{
eStatus = MB_EPORTERR;
}
else if( xMBPortTimersInit( MB_ASCII_TIMEOUT_SEC * 20000UL ) != TRUE )
{
eStatus = MB_EPORTERR;
}
EXIT_CRITICAL_SECTION( );
return eStatus;
}
void
eMBASCIIStart( void )
{
ENTER_CRITICAL_SECTION( );
vMBPortSerialEnable( TRUE, FALSE );
eRcvState = STATE_RX_IDLE;
EXIT_CRITICAL_SECTION( );
/* No special startup required for ASCII. */
( void )xMBPortEventPost( EV_READY );
}
void
eMBASCIIStop( void )
{
ENTER_CRITICAL_SECTION( );
vMBPortSerialEnable( FALSE, FALSE );
vMBPortTimersDisable( );
EXIT_CRITICAL_SECTION( );
}
eMBErrorCode
eMBASCIIReceive( UCHAR * pucRcvAddress, UCHAR ** pucFrame, USHORT * pusLength )
{
eMBErrorCode eStatus = MB_ENOERR;
ENTER_CRITICAL_SECTION( );
assert( usRcvBufferPos < MB_SER_PDU_SIZE_MAX );
/* Length and CRC check */
if( ( usRcvBufferPos >= MB_SER_PDU_SIZE_MIN )
&& ( prvucMBLRC( ( UCHAR * ) ucASCIIBuf, usRcvBufferPos ) == 0 ) )
{
/* Save the address field. All frames are passed to the upper layed
* and the decision if a frame is used is done there.
*/
*pucRcvAddress = ucASCIIBuf[MB_SER_PDU_ADDR_OFF];
/* Total length of Modbus-PDU is Modbus-Serial-Line-PDU minus
* size of address field and CRC checksum.
*/
*pusLength = ( USHORT )( usRcvBufferPos - MB_SER_PDU_PDU_OFF - MB_SER_PDU_SIZE_LRC );
/* Return the start of the Modbus PDU to the caller. */
*pucFrame = ( UCHAR * ) & ucASCIIBuf[MB_SER_PDU_PDU_OFF];
}
else
{
eStatus = MB_EIO;
}
EXIT_CRITICAL_SECTION( );
return eStatus;
}
eMBErrorCode
eMBASCIISend( UCHAR ucSlaveAddress, const UCHAR * pucFrame, USHORT usLength )
{
eMBErrorCode eStatus = MB_ENOERR;
UCHAR usLRC;
ENTER_CRITICAL_SECTION( );
/* Check if the receiver is still in idle state. If not we where too
* 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 LRC checksum for Modbus-Serial-Line-PDU. */
usLRC = prvucMBLRC( ( UCHAR * ) pucSndBufferCur, usSndBufferCount );
ucASCIIBuf[usSndBufferCount++] = usLRC;
/* Activate the transmitter. */
eSndState = STATE_TX_START;
vMBPortSerialEnable( FALSE, TRUE );
}
else
{
eStatus = MB_EIO;
}
EXIT_CRITICAL_SECTION( );
return eStatus;
}
BOOL
xMBASCIIReceiveFSM( void )
{
BOOL xNeedPoll = FALSE;
UCHAR ucByte;
UCHAR ucResult;
assert( eSndState == STATE_TX_IDLE );
( void )xMBPortSerialGetByte( ( CHAR * ) & ucByte );
switch ( eRcvState )
{
/* A new character is received. If the character is a ':' the input
* buffer is cleared. A CR-character signals the end of the data
* block. Other characters are part of the data block and their
* ASCII value is converted back to a binary representation.
*/
case STATE_RX_RCV:
/* Enable timer for character timeout. */
vMBPortTimersEnable( );
if( ucByte == ':' )
{
/* Empty receive buffer. */
eBytePos = BYTE_HIGH_NIBBLE;
usRcvBufferPos = 0;
}
else if( ucByte == MB_ASCII_DEFAULT_CR )
{
eRcvState = STATE_RX_WAIT_EOF;
}
else
{
ucResult = prvucMBCHAR2BIN( ucByte );
switch ( eBytePos )
{
/* High nibble of the byte comes first. We check for
* a buffer overflow here. */
case BYTE_HIGH_NIBBLE:
if( usRcvBufferPos < MB_SER_PDU_SIZE_MAX )
{
ucASCIIBuf[usRcvBufferPos] = ( UCHAR )( ucResult << 4 );
eBytePos = BYTE_LOW_NIBBLE;
break;
}
else
{
/* not handled in Modbus specification but seems
* a resonable implementation. */
eRcvState = STATE_RX_IDLE;
/* Disable previously activated timer because of error state. */
vMBPortTimersDisable( );
}
break;
case BYTE_LOW_NIBBLE:
ucASCIIBuf[usRcvBufferPos] |= ucResult;
usRcvBufferPos++;
eBytePos = BYTE_HIGH_NIBBLE;
break;
}
}
break;
case STATE_RX_WAIT_EOF:
if( ucByte == ucMBLFCharacter )
{
/* Disable character timeout timer because all characters are
* received. */
vMBPortTimersDisable( );
/* Receiver is again in idle state. */
eRcvState = STATE_RX_IDLE;
/* Notify the caller of eMBASCIIReceive that a new frame
* was received. */
xNeedPoll = xMBPortEventPost( EV_FRAME_RECEIVED );
}
else if( ucByte == ':' )
{
/* Empty receive buffer and back to receive state. */
eBytePos = BYTE_HIGH_NIBBLE;
usRcvBufferPos = 0;
eRcvState = STATE_RX_RCV;
/* Enable timer for character timeout. */
vMBPortTimersEnable( );
}
else
{
/* Frame is not okay. Delete entire frame. */
eRcvState = STATE_RX_IDLE;
}
break;
case STATE_RX_IDLE:
if( ucByte == ':' )
{
/* Enable timer for character timeout. */
vMBPortTimersEnable( );
/* Reset the input buffers to store the frame. */
usRcvBufferPos = 0;;
eBytePos = BYTE_HIGH_NIBBLE;
eRcvState = STATE_RX_RCV;
}
break;
}
return xNeedPoll;
}
BOOL
xMBASCIITransmitFSM( void )
{
BOOL xNeedPoll = FALSE;
UCHAR ucByte;
assert( eRcvState == STATE_RX_IDLE );
switch ( eSndState )
{
/* Start of transmission. The start of a frame is defined by sending
* the character ':'. */
case STATE_TX_START:
ucByte = ':';
xMBPortSerialPutByte( ( CHAR )ucByte );
eSndState = STATE_TX_DATA;
eBytePos = BYTE_HIGH_NIBBLE;
break;
/* Send the data block. Each data byte is encoded as a character hex
* stream with the high nibble sent first and the low nibble sent
* last. If all data bytes are exhausted we send a '\r' character
* to end the transmission. */
case STATE_TX_DATA:
if( usSndBufferCount > 0 )
{
switch ( eBytePos )
{
case BYTE_HIGH_NIBBLE:
ucByte = prvucMBBIN2CHAR( ( UCHAR )( *pucSndBufferCur >> 4 ) );
xMBPortSerialPutByte( ( CHAR ) ucByte );
eBytePos = BYTE_LOW_NIBBLE;
break;
case BYTE_LOW_NIBBLE:
ucByte = prvucMBBIN2CHAR( ( UCHAR )( *pucSndBufferCur & 0x0F ) );
xMBPortSerialPutByte( ( CHAR )ucByte );
pucSndBufferCur++;
eBytePos = BYTE_HIGH_NIBBLE;
usSndBufferCount--;
break;
}
}
else
{
xMBPortSerialPutByte( MB_ASCII_DEFAULT_CR );
eSndState = STATE_TX_END;
}
break;
/* Finish the frame by sending a LF character. */
case STATE_TX_END:
xMBPortSerialPutByte( ( CHAR )ucMBLFCharacter );
/* We need another state to make sure that the CR character has
* been sent. */
eSndState = STATE_TX_NOTIFY;
break;
/* Notify the task which called eMBASCIISend that the frame has
* been sent. */
case STATE_TX_NOTIFY:
eSndState = STATE_TX_IDLE;
xNeedPoll = xMBPortEventPost( EV_FRAME_SENT );
/* Disable transmitter. This prevents another transmit buffer
* empty interrupt. */
vMBPortSerialEnable( TRUE, FALSE );
eSndState = STATE_TX_IDLE;
break;
/* We should not get a transmitter event if the transmitter is in
* idle state. */
case STATE_TX_IDLE:
/* enable receiver/disable transmitter. */
vMBPortSerialEnable( TRUE, FALSE );
break;
}
return xNeedPoll;
}
BOOL
xMBASCIITimerT1SExpired( void )
{
switch ( eRcvState )
{
/* If we have a timeout we go back to the idle state and wait for
* the next frame.
*/
case STATE_RX_RCV:
case STATE_RX_WAIT_EOF:
eRcvState = STATE_RX_IDLE;
break;
default:
assert( ( eRcvState == STATE_RX_RCV ) || ( eRcvState == STATE_RX_WAIT_EOF ) );
break;
}
vMBPortTimersDisable( );
/* no context switch required. */
return FALSE;
}
static UCHAR
prvucMBCHAR2BIN( UCHAR ucCharacter )
{
if( ( ucCharacter >= '0' ) && ( ucCharacter <= '9' ) )
{
return ( UCHAR )( ucCharacter - '0' );
}
else if( ( ucCharacter >= 'A' ) && ( ucCharacter <= 'F' ) )
{
return ( UCHAR )( ucCharacter - 'A' + 0x0A );
}
else
{
return 0xFF;
}
}
static UCHAR
prvucMBBIN2CHAR( UCHAR ucByte )
{
if( ucByte <= 0x09 )
{
return ( UCHAR )( '0' + ucByte );
}
else if( ( ucByte >= 0x0A ) && ( ucByte <= 0x0F ) )
{
return ( UCHAR )( ucByte - 0x0A + 'A' );
}
else
{
/* Programming error. */
assert( 0 );
}
return '0';
}
static UCHAR
prvucMBLRC( UCHAR * pucFrame, USHORT usLen )
{
UCHAR ucLRC = 0; /* LRC char initialized */
while( usLen-- )
{
ucLRC += *pucFrame++; /* Add buffer byte without carry */
}
/* Return twos complement */
ucLRC = ( UCHAR ) ( -( ( CHAR ) ucLRC ) );
return ucLRC;
}
#endif
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