/* * FreeModbus Libary: A portable Modbus implementation for Modbus ASCII/RTU. * Copyright (c) 2006 Christian Walter * 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( ); } // The lines below are required to suppress GCC warnings about unused but set variable 'xFrameReceived' // This warning is treated as error during compilation. #pragma GCC diagnostic push // required for GCC #pragma GCC diagnostic ignored "-Wunused-but-set-variable" 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 layed * 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; } else { eStatus = MB_EIO; } EXIT_CRITICAL_SECTION( ); return eStatus; } #pragma GCC diagnostic pop // require GCC 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_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; 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; }