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nuttx-apps/modbus/rtu/mbrtu.c

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/****************************************************************************
* apps/modbus/rtu/mbrtu.c
*
* FreeModbus Library: 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.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include "port.h"
#include "modbus/mb.h"
#include "modbus/mbframe.h"
#include "modbus/mbport.h"
#include "mbrtu.h"
#include "mbcrc.h"
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
#define MB_SER_PDU_SIZE_MIN 4 /* Minimum size of a Modbus RTU frame. */
#define MB_SER_PDU_SIZE_MAX 256 /* Maximum size of a Modbus RTU frame. */
#define MB_SER_PDU_SIZE_CRC 2 /* Size of CRC 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. */
/****************************************************************************
* Private Type Definitions
****************************************************************************/
typedef enum
{
STATE_RX_INIT, /* Receiver is in initial state. */
STATE_RX_IDLE, /* Receiver is in idle state. */
STATE_RX_RCV, /* Frame is being received. */
STATE_RX_ERROR /* If the frame is invalid. */
} eMBRcvState;
typedef enum
{
STATE_TX_IDLE, /* Transmitter is in idle state. */
STATE_TX_XMIT /* Transmitter is in transfer state. */
} eMBSndState;
/****************************************************************************
* Private Data
****************************************************************************/
static volatile eMBSndState eSndState;
static volatile eMBRcvState eRcvState;
volatile uint8_t ucRTUBuf[MB_SER_PDU_SIZE_MAX];
static volatile uint8_t *pucSndBufferCur;
static volatile uint16_t usSndBufferCount;
static volatile uint16_t usRcvBufferPos;
/****************************************************************************
* Public Functions
****************************************************************************/
eMBErrorCode eMBRTUInit(uint8_t ucSlaveAddress, uint8_t ucPort,
speed_t ulBaudRate, eMBParity eParity)
{
eMBErrorCode eStatus = MB_ENOERR;
uint32_t usTimerT35_50us;
ENTER_CRITICAL_SECTION();
/* Modbus RTU uses 8 Databits. */
if (xMBPortSerialInit(ucPort, ulBaudRate, 8, eParity) != true)
{
eStatus = MB_EPORTERR;
}
else
{
/* If baudrate > 19200 then we should use the fixed timer values
* t35 = 1750us. Otherwise t35 must be 3.5 times the character time.
*/
if (ulBaudRate > 19200)
{
usTimerT35_50us = 35; /* 1800us. */
}
else
{
/* The timer reload value for a character is given by:
*
* ChTimeValue = Ticks_per_1s / (Baudrate / 11)
* = 11 * Ticks_per_1s / Baudrate
* = 220000 / Baudrate
* The reload for t3.5 is 1.5 times this value and similarly
* for t3.5.
*/
usTimerT35_50us = (7UL * 220000UL) / (2UL * ulBaudRate);
}
if (xMBPortTimersInit((uint16_t) usTimerT35_50us) != true)
{
eStatus = MB_EPORTERR;
}
}
EXIT_CRITICAL_SECTION();
return eStatus;
}
void eMBRTUStart(void)
{
ENTER_CRITICAL_SECTION();
/* Initially the receiver is in the state STATE_RX_INIT. we start
* the timer and if no character is received within t3.5 we change
* to STATE_RX_IDLE. This makes sure that we delay startup of the
* modbus protocol stack until the bus is free.
*/
eRcvState = STATE_RX_INIT;
vMBPortSerialEnable(true, false);
vMBPortTimersEnable();
EXIT_CRITICAL_SECTION();
}
void eMBRTUStop(void)
{
ENTER_CRITICAL_SECTION();
vMBPortSerialEnable(false, false);
vMBPortTimersDisable();
EXIT_CRITICAL_SECTION();
}
eMBErrorCode eMBRTUReceive(uint8_t *pucRcvAddress, uint8_t **pucFrame,
uint16_t *pusLength)
{
eMBErrorCode eStatus = MB_ENOERR;
ENTER_CRITICAL_SECTION();
DEBUGASSERT(usRcvBufferPos < MB_SER_PDU_SIZE_MAX);
/* Length and CRC check */
if ((usRcvBufferPos >= MB_SER_PDU_SIZE_MIN) &&
(usMBCRC16((uint8_t *) ucRTUBuf, usRcvBufferPos) == 0))
{
/* Save the address field. All frames are passed to the upper laid
* and the decision if a frame is used is done there.
*/
*pucRcvAddress = ucRTUBuf[MB_SER_PDU_ADDR_OFF];
/* Total length of Modbus-PDU is Modbus-Serial-Line-PDU minus
* size of address field and CRC checksum.
*/
*pusLength = (uint16_t)(usRcvBufferPos - MB_SER_PDU_PDU_OFF - MB_SER_PDU_SIZE_CRC);
/* Return the start of the Modbus PDU to the caller. */
*pucFrame = (uint8_t *) & ucRTUBuf[MB_SER_PDU_PDU_OFF];
}
else
{
eStatus = MB_EIO;
}
EXIT_CRITICAL_SECTION();
return eStatus;
}
eMBErrorCode eMBRTUSend(uint8_t ucSlaveAddress, const uint8_t *pucFrame, uint16_t usLength)
{
eMBErrorCode eStatus = MB_ENOERR;
uint16_t 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 = (uint8_t *) 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((uint8_t *) pucSndBufferCur, usSndBufferCount);
ucRTUBuf[usSndBufferCount++] = (uint8_t)(usCRC16 & 0xFF);
ucRTUBuf[usSndBufferCount++] = (uint8_t)(usCRC16 >> 8);
/* Activate the transmitter. */
eSndState = STATE_TX_XMIT;
vMBPortSerialEnable(false, true);
}
else
{
eStatus = MB_EIO;
}
EXIT_CRITICAL_SECTION();
return eStatus;
}
bool xMBRTUReceiveFSM(void)
{
bool xTaskNeedSwitch = false;
uint8_t ucByte;
DEBUGASSERT(eSndState == STATE_TX_IDLE);
/* Always read the character. */
xMBPortSerialGetByte((int8_t *) & ucByte);
switch (eRcvState)
{
/* If we have received a character in the init state we have to
* wait until the frame is finished.
*/
case STATE_RX_INIT:
vMBPortTimersEnable();
break;
/* In the error state we wait until all characters in the
* damaged frame are transmitted.
*/
case STATE_RX_ERROR:
vMBPortTimersEnable();
break;
/* In the idle state we wait for a new character. If a character
* is received the t1.5 and t3.5 timers are started and the
* receiver is in the state STATE_RX_RECEIVCE.
*/
case STATE_RX_IDLE:
usRcvBufferPos = 0;
ucRTUBuf[usRcvBufferPos++] = ucByte;
eRcvState = STATE_RX_RCV;
/* Enable t3.5 timers. */
vMBPortTimersEnable();
break;
/* We are currently receiving a frame. Reset the timer after
* every character received. If more than the maximum possible
* number of bytes in a modbus frame is received the frame is
* ignored.
*/
case STATE_RX_RCV:
if (usRcvBufferPos < MB_SER_PDU_SIZE_MAX)
{
ucRTUBuf[usRcvBufferPos++] = ucByte;
}
else
{
eRcvState = STATE_RX_ERROR;
}
vMBPortTimersEnable();
break;
}
return xTaskNeedSwitch;
}
bool xMBRTUTransmitFSM(void)
{
bool xNeedPoll = false;
DEBUGASSERT(eRcvState == STATE_RX_IDLE);
switch (eSndState)
{
/* 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;
case STATE_TX_XMIT:
/* check if we are finished. */
if (usSndBufferCount != 0)
{
xMBPortSerialPutByte((int8_t)*pucSndBufferCur);
pucSndBufferCur++; /* next byte in sendbuffer. */
usSndBufferCount--;
}
else
{
xNeedPoll = xMBPortEventPost(EV_FRAME_SENT);
/* Disable transmitter. This prevents another transmit buffer
* empty interrupt.
*/
vMBPortSerialEnable(true, false);
eSndState = STATE_TX_IDLE;
}
break;
}
return xNeedPoll;
}
bool xMBRTUTimerT35Expired(void)
{
bool xNeedPoll = false;
switch (eRcvState)
{
/* Timer t35 expired. Start-up phase is finished. */
case STATE_RX_INIT:
xNeedPoll = xMBPortEventPost(EV_READY);
break;
/* A frame was received and t35 expired. Notify the listener that
* a new frame was received.
*/
case STATE_RX_RCV:
xNeedPoll = xMBPortEventPost(EV_FRAME_RECEIVED);
break;
/* An error occurred while receiving the frame. */
case STATE_RX_ERROR:
break;
/* Function called in an illegal state. */
default:
DEBUGASSERT((eRcvState == STATE_RX_INIT) ||
(eRcvState == STATE_RX_RCV) ||
(eRcvState == STATE_RX_ERROR));
}
vMBPortTimersDisable();
eRcvState = STATE_RX_IDLE;
return xNeedPoll;
}
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