Diff: mbrtu.cpp

Revision:

0:0453a0a7e500

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbrtu.cpp	Thu Apr 15 12:10:34 2010 +0000
@@ -0,0 +1,358 @@
+/* 
+ * 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: mbrtu.c,v 1.18 2007/09/12 10:15:56 wolti Exp $
+ */
+
+/* ----------------------- System includes ----------------------------------*/
+#include "stdlib.h"
+#include "string.h"
+
+/* ----------------------- Platform includes --------------------------------*/
+#include "port.h"
+
+/* ----------------------- Modbus includes ----------------------------------*/
+#include "mb.h"
+#include "mbrtu.h"
+#include "mbframe.h"
+
+#include "mbcrc.h"
+#include "mbport.h"
+
+/* ----------------------- Defines ------------------------------------------*/
+#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. */
+
+/* ----------------------- 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 beeing 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;
+
+/* ----------------------- Static variables ---------------------------------*/
+static volatile eMBSndState eSndState;
+static volatile eMBRcvState eRcvState;
+
+volatile UCHAR  ucRTUBuf[MB_SER_PDU_SIZE_MAX];
+
+static volatile UCHAR *pucSndBufferCur;
+static volatile USHORT usSndBufferCount;
+
+static volatile USHORT usRcvBufferPos;
+
+/* ----------------------- Start implementation -----------------------------*/
+eMBErrorCode
+eMBRTUInit( UCHAR ucSlaveAddress, UCHAR ucPort, ULONG ulBaudRate, eMBParity eParity )
+{
+    eMBErrorCode    eStatus = MB_ENOERR;
+    ULONG           usTimerT35_50us;
+
+    ( void )ucSlaveAddress;
+    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 similary
+             * for t3.5.
+             */
+            usTimerT35_50us = ( 7UL * 220000UL ) / ( 2UL * ulBaudRate );
+        }
+        if( xMBPortTimersInit( ( USHORT ) 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( UCHAR * pucRcvAddress, UCHAR ** pucFrame, USHORT * pusLength )
+{
+    BOOL            xFrameReceived = FALSE;
+    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 )
+        && ( usMBCRC16( ( UCHAR * ) ucRTUBuf, usRcvBufferPos ) == 0 ) )
+    {
+        /* Save the address field. All frames are passed to the upper layer
+         * 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 = ( USHORT )( usRcvBufferPos - MB_SER_PDU_PDU_OFF - MB_SER_PDU_SIZE_CRC );
+
+        /* Return the start of the Modbus PDU to the caller. */
+        *pucFrame = ( UCHAR * ) & ucRTUBuf[MB_SER_PDU_PDU_OFF];
+        xFrameReceived = TRUE;
+        
+        // Added by Cam
+        // Now that the poll routine knows about the received frame, 
+        // clear the receive buffer position ready for the next frame received
+        usRcvBufferPos = 0;
+
+    }
+    else
+    {
+        eStatus = MB_EIO;
+    }
+
+    EXIT_CRITICAL_SECTION(  );
+    return eStatus;
+}
+
+eMBErrorCode
+eMBRTUSend( UCHAR ucSlaveAddress, const UCHAR * pucFrame, USHORT usLength )
+{
+    eMBErrorCode    eStatus = MB_ENOERR;
+    USHORT          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 = ( 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 CRC16 checksum for Modbus-Serial-Line-PDU. */
+        usCRC16 = usMBCRC16( ( UCHAR * ) pucSndBufferCur, usSndBufferCount );
+        ucRTUBuf[usSndBufferCount++] = ( UCHAR )( usCRC16 & 0xFF );
+        ucRTUBuf[usSndBufferCount++] = ( UCHAR )( 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;
+    UCHAR           ucByte;
+
+    assert( eSndState == STATE_TX_IDLE );
+
+    /* Always read the character. */
+    ( void )xMBPortSerialGetByte( ( CHAR * ) & 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_RECEIVE.
+         */
+    case STATE_RX_IDLE:
+        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;
+
+    assert( 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( ( CHAR )*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. Startup 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 occured while receiving the frame. */
+    case STATE_RX_ERROR:
+        break;
+
+        /* Function called in an illegal state. */
+    default:
+        assert( ( eRcvState == STATE_RX_INIT ) ||
+                ( eRcvState == STATE_RX_RCV ) || ( eRcvState == STATE_RX_ERROR ) );
+    }
+
+    vMBPortTimersDisable(  );
+    eRcvState = STATE_RX_IDLE;
+
+    return xNeedPoll;
+}