/**************************************************************************** * apps/modbus/rtu/mbrtu.c * * FreeModbus Library: 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. * ****************************************************************************/ /**************************************************************************** * Included Files ****************************************************************************/ #include #include #include #include #include "port.h" #include #include #include #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; (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((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(); ASSERT(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 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 = (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; ASSERT(eSndState == STATE_TX_IDLE); /* Always read the character. */ (void)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; 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((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: ASSERT((eRcvState == STATE_RX_INIT) || (eRcvState == STATE_RX_RCV) || (eRcvState == STATE_RX_ERROR)); } vMBPortTimersDisable(); eRcvState = STATE_RX_IDLE; return xNeedPoll; }