361 lines
11 KiB
C
361 lines
11 KiB
C
/*
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* FreeModbus Libary: A portable Modbus implementation for Modbus ASCII/RTU.
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* Copyright (c) 2006 Christian Walter <wolti@sil.at>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* File: $Id: mbrtu.c,v 1.18 2007/09/12 10:15:56 wolti Exp $
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*/
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/* ----------------------- System includes ----------------------------------*/
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#include <nuttx/config.h>
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#include <stdlib.h>
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#include <string.h>
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#include <assert.h>
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/* ----------------------- Platform includes --------------------------------*/
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#include "port.h"
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/* ----------------------- Modbus includes ----------------------------------*/
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#include <apps/modbus/mb.h>
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#include <apps/modbus/mbframe.h>
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#include <apps/modbus/mbport.h>
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#include "mbrtu.h"
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#include "mbcrc.h"
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/* ----------------------- Defines ------------------------------------------*/
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#define MB_SER_PDU_SIZE_MIN 4 /*!< Minimum size of a Modbus RTU frame. */
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#define MB_SER_PDU_SIZE_MAX 256 /*!< Maximum size of a Modbus RTU frame. */
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#define MB_SER_PDU_SIZE_CRC 2 /*!< Size of CRC field in PDU. */
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#define MB_SER_PDU_ADDR_OFF 0 /*!< Offset of slave address in Ser-PDU. */
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#define MB_SER_PDU_PDU_OFF 1 /*!< Offset of Modbus-PDU in Ser-PDU. */
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/* ----------------------- Type definitions ---------------------------------*/
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typedef enum
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{
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STATE_RX_INIT, /*!< Receiver is in initial state. */
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STATE_RX_IDLE, /*!< Receiver is in idle state. */
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STATE_RX_RCV, /*!< Frame is beeing received. */
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STATE_RX_ERROR /*!< If the frame is invalid. */
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} eMBRcvState;
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typedef enum
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{
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STATE_TX_IDLE, /*!< Transmitter is in idle state. */
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STATE_TX_XMIT /*!< Transmitter is in transfer state. */
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} eMBSndState;
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/* ----------------------- Static variables ---------------------------------*/
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static volatile eMBSndState eSndState;
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static volatile eMBRcvState eRcvState;
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volatile uint8_t ucRTUBuf[MB_SER_PDU_SIZE_MAX];
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static volatile uint8_t *pucSndBufferCur;
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static volatile uint16_t usSndBufferCount;
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static volatile uint16_t usRcvBufferPos;
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/* ----------------------- Start implementation -----------------------------*/
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eMBErrorCode
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eMBRTUInit(uint8_t ucSlaveAddress, uint8_t ucPort, speed_t ulBaudRate, eMBParity eParity)
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{
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eMBErrorCode eStatus = MB_ENOERR;
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uint32_t usTimerT35_50us;
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(void)ucSlaveAddress;
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ENTER_CRITICAL_SECTION();
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/* Modbus RTU uses 8 Databits. */
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if (xMBPortSerialInit(ucPort, ulBaudRate, 8, eParity) != true)
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{
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eStatus = MB_EPORTERR;
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}
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else
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{
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/* If baudrate > 19200 then we should use the fixed timer values
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* t35 = 1750us. Otherwise t35 must be 3.5 times the character time.
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*/
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if (ulBaudRate > 19200)
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{
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usTimerT35_50us = 35; /* 1800us. */
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}
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else
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{
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/* The timer reload value for a character is given by:
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*
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* ChTimeValue = Ticks_per_1s / (Baudrate / 11)
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* = 11 * Ticks_per_1s / Baudrate
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* = 220000 / Baudrate
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* The reload for t3.5 is 1.5 times this value and similary
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* for t3.5.
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*/
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usTimerT35_50us = (7UL * 220000UL) / (2UL * ulBaudRate);
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}
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if (xMBPortTimersInit((uint16_t) usTimerT35_50us) != true)
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{
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eStatus = MB_EPORTERR;
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}
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}
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EXIT_CRITICAL_SECTION();
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return eStatus;
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}
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void
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eMBRTUStart(void)
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{
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ENTER_CRITICAL_SECTION();
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/* Initially the receiver is in the state STATE_RX_INIT. we start
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* the timer and if no character is received within t3.5 we change
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* to STATE_RX_IDLE. This makes sure that we delay startup of the
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* modbus protocol stack until the bus is free.
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*/
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eRcvState = STATE_RX_INIT;
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vMBPortSerialEnable(true, false);
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vMBPortTimersEnable();
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EXIT_CRITICAL_SECTION();
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}
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void
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eMBRTUStop(void)
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{
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ENTER_CRITICAL_SECTION();
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vMBPortSerialEnable(false, false);
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vMBPortTimersDisable();
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EXIT_CRITICAL_SECTION();
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}
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eMBErrorCode
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eMBRTUReceive(uint8_t * pucRcvAddress, uint8_t ** pucFrame, uint16_t * pusLength)
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{
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eMBErrorCode eStatus = MB_ENOERR;
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ENTER_CRITICAL_SECTION();
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ASSERT(usRcvBufferPos < MB_SER_PDU_SIZE_MAX);
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/* Length and CRC check */
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if ((usRcvBufferPos >= MB_SER_PDU_SIZE_MIN)
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&& (usMBCRC16((uint8_t *) ucRTUBuf, usRcvBufferPos) == 0))
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{
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/* Save the address field. All frames are passed to the upper layed
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* and the decision if a frame is used is done there.
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*/
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*pucRcvAddress = ucRTUBuf[MB_SER_PDU_ADDR_OFF];
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/* Total length of Modbus-PDU is Modbus-Serial-Line-PDU minus
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* size of address field and CRC checksum.
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*/
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*pusLength = (uint16_t)(usRcvBufferPos - MB_SER_PDU_PDU_OFF - MB_SER_PDU_SIZE_CRC);
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/* Return the start of the Modbus PDU to the caller. */
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*pucFrame = (uint8_t *) & ucRTUBuf[MB_SER_PDU_PDU_OFF];
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}
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else
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{
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eStatus = MB_EIO;
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}
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EXIT_CRITICAL_SECTION();
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return eStatus;
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}
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eMBErrorCode
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eMBRTUSend(uint8_t ucSlaveAddress, const uint8_t * pucFrame, uint16_t usLength)
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{
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eMBErrorCode eStatus = MB_ENOERR;
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uint16_t usCRC16;
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ENTER_CRITICAL_SECTION();
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/* Check if the receiver is still in idle state. If not we where to
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* slow with processing the received frame and the master sent another
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* frame on the network. We have to abort sending the frame.
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*/
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if (eRcvState == STATE_RX_IDLE)
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{
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/* First byte before the Modbus-PDU is the slave address. */
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pucSndBufferCur = (uint8_t *) pucFrame - 1;
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usSndBufferCount = 1;
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/* Now copy the Modbus-PDU into the Modbus-Serial-Line-PDU. */
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pucSndBufferCur[MB_SER_PDU_ADDR_OFF] = ucSlaveAddress;
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usSndBufferCount += usLength;
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/* Calculate CRC16 checksum for Modbus-Serial-Line-PDU. */
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usCRC16 = usMBCRC16((uint8_t *) pucSndBufferCur, usSndBufferCount);
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ucRTUBuf[usSndBufferCount++] = (uint8_t)(usCRC16 & 0xFF);
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ucRTUBuf[usSndBufferCount++] = (uint8_t)(usCRC16 >> 8);
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/* Activate the transmitter. */
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eSndState = STATE_TX_XMIT;
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vMBPortSerialEnable(false, true);
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}
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else
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{
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eStatus = MB_EIO;
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}
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EXIT_CRITICAL_SECTION();
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return eStatus;
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}
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bool
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xMBRTUReceiveFSM(void)
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{
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bool xTaskNeedSwitch = false;
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uint8_t ucByte;
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ASSERT(eSndState == STATE_TX_IDLE);
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/* Always read the character. */
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(void)xMBPortSerialGetByte((int8_t *) & ucByte);
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switch (eRcvState)
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{
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/* If we have received a character in the init state we have to
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* wait until the frame is finished.
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*/
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case STATE_RX_INIT:
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vMBPortTimersEnable();
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break;
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/* In the error state we wait until all characters in the
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* damaged frame are transmitted.
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*/
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case STATE_RX_ERROR:
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vMBPortTimersEnable();
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break;
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/* In the idle state we wait for a new character. If a character
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* is received the t1.5 and t3.5 timers are started and the
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* receiver is in the state STATE_RX_RECEIVCE.
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*/
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case STATE_RX_IDLE:
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usRcvBufferPos = 0;
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ucRTUBuf[usRcvBufferPos++] = ucByte;
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eRcvState = STATE_RX_RCV;
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/* Enable t3.5 timers. */
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vMBPortTimersEnable();
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break;
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/* We are currently receiving a frame. Reset the timer after
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* every character received. If more than the maximum possible
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* number of bytes in a modbus frame is received the frame is
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* ignored.
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*/
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case STATE_RX_RCV:
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if (usRcvBufferPos < MB_SER_PDU_SIZE_MAX)
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{
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ucRTUBuf[usRcvBufferPos++] = ucByte;
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}
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else
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{
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eRcvState = STATE_RX_ERROR;
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}
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vMBPortTimersEnable();
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break;
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}
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return xTaskNeedSwitch;
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}
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bool
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xMBRTUTransmitFSM(void)
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{
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bool xNeedPoll = false;
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ASSERT(eRcvState == STATE_RX_IDLE);
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switch (eSndState)
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{
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/* We should not get a transmitter event if the transmitter is in
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* idle state. */
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case STATE_TX_IDLE:
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/* enable receiver/disable transmitter. */
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vMBPortSerialEnable(true, false);
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break;
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case STATE_TX_XMIT:
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/* check if we are finished. */
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if (usSndBufferCount != 0)
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{
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xMBPortSerialPutByte((int8_t)*pucSndBufferCur);
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pucSndBufferCur++; /* next byte in sendbuffer. */
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usSndBufferCount--;
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}
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else
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{
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xNeedPoll = xMBPortEventPost(EV_FRAME_SENT);
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/* Disable transmitter. This prevents another transmit buffer
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* empty interrupt. */
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vMBPortSerialEnable(true, false);
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eSndState = STATE_TX_IDLE;
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}
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break;
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}
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return xNeedPoll;
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}
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bool
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xMBRTUTimerT35Expired(void)
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{
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bool xNeedPoll = false;
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switch (eRcvState)
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{
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/* Timer t35 expired. Startup phase is finished. */
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case STATE_RX_INIT:
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xNeedPoll = xMBPortEventPost(EV_READY);
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break;
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/* A frame was received and t35 expired. Notify the listener that
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* a new frame was received. */
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case STATE_RX_RCV:
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xNeedPoll = xMBPortEventPost(EV_FRAME_RECEIVED);
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break;
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/* An error occured while receiving the frame. */
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case STATE_RX_ERROR:
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break;
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/* Function called in an illegal state. */
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default:
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ASSERT((eRcvState == STATE_RX_INIT) ||
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(eRcvState == STATE_RX_RCV) || (eRcvState == STATE_RX_ERROR));
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}
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vMBPortTimersDisable();
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eRcvState = STATE_RX_IDLE;
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return xNeedPoll;
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}
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