/* * Copyright © Stéphane Raimbault * * SPDX-License-Identifier: LGPL-2.1-or-later */ #include #include #include #include #include #ifndef _MSC_VER #include #endif #include "modbus-private.h" #include #include "modbus-rtu-private.h" #include "modbus-rtu.h" #if HAVE_DECL_TIOCSRS485 || HAVE_DECL_TIOCM_RTS #include #endif #if HAVE_DECL_TIOCSRS485 #include #endif /* Table of CRC values for high-order byte */ static const uint8_t table_crc_hi[] = { 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40}; /* Table of CRC values for low-order byte */ static const uint8_t table_crc_lo[] = { 0x00, 0xC0, 0xC1, 0x01, 0xC3, 0x03, 0x02, 0xC2, 0xC6, 0x06, 0x07, 0xC7, 0x05, 0xC5, 0xC4, 0x04, 0xCC, 0x0C, 0x0D, 0xCD, 0x0F, 0xCF, 0xCE, 0x0E, 0x0A, 0xCA, 0xCB, 0x0B, 0xC9, 0x09, 0x08, 0xC8, 0xD8, 0x18, 0x19, 0xD9, 0x1B, 0xDB, 0xDA, 0x1A, 0x1E, 0xDE, 0xDF, 0x1F, 0xDD, 0x1D, 0x1C, 0xDC, 0x14, 0xD4, 0xD5, 0x15, 0xD7, 0x17, 0x16, 0xD6, 0xD2, 0x12, 0x13, 0xD3, 0x11, 0xD1, 0xD0, 0x10, 0xF0, 0x30, 0x31, 0xF1, 0x33, 0xF3, 0xF2, 0x32, 0x36, 0xF6, 0xF7, 0x37, 0xF5, 0x35, 0x34, 0xF4, 0x3C, 0xFC, 0xFD, 0x3D, 0xFF, 0x3F, 0x3E, 0xFE, 0xFA, 0x3A, 0x3B, 0xFB, 0x39, 0xF9, 0xF8, 0x38, 0x28, 0xE8, 0xE9, 0x29, 0xEB, 0x2B, 0x2A, 0xEA, 0xEE, 0x2E, 0x2F, 0xEF, 0x2D, 0xED, 0xEC, 0x2C, 0xE4, 0x24, 0x25, 0xE5, 0x27, 0xE7, 0xE6, 0x26, 0x22, 0xE2, 0xE3, 0x23, 0xE1, 0x21, 0x20, 0xE0, 0xA0, 0x60, 0x61, 0xA1, 0x63, 0xA3, 0xA2, 0x62, 0x66, 0xA6, 0xA7, 0x67, 0xA5, 0x65, 0x64, 0xA4, 0x6C, 0xAC, 0xAD, 0x6D, 0xAF, 0x6F, 0x6E, 0xAE, 0xAA, 0x6A, 0x6B, 0xAB, 0x69, 0xA9, 0xA8, 0x68, 0x78, 0xB8, 0xB9, 0x79, 0xBB, 0x7B, 0x7A, 0xBA, 0xBE, 0x7E, 0x7F, 0xBF, 0x7D, 0xBD, 0xBC, 0x7C, 0xB4, 0x74, 0x75, 0xB5, 0x77, 0xB7, 0xB6, 0x76, 0x72, 0xB2, 0xB3, 0x73, 0xB1, 0x71, 0x70, 0xB0, 0x50, 0x90, 0x91, 0x51, 0x93, 0x53, 0x52, 0x92, 0x96, 0x56, 0x57, 0x97, 0x55, 0x95, 0x94, 0x54, 0x9C, 0x5C, 0x5D, 0x9D, 0x5F, 0x9F, 0x9E, 0x5E, 0x5A, 0x9A, 0x9B, 0x5B, 0x99, 0x59, 0x58, 0x98, 0x88, 0x48, 0x49, 0x89, 0x4B, 0x8B, 0x8A, 0x4A, 0x4E, 0x8E, 0x8F, 0x4F, 0x8D, 0x4D, 0x4C, 0x8C, 0x44, 0x84, 0x85, 0x45, 0x87, 0x47, 0x46, 0x86, 0x82, 0x42, 0x43, 0x83, 0x41, 0x81, 0x80, 0x40}; /* Define the slave ID of the remote device to talk in master mode or set the * internal slave ID in slave mode */ static int _modbus_set_slave(modbus_t *ctx, int slave) { int max_slave = (ctx->quirks & MODBUS_QUIRK_MAX_SLAVE) ? 255 : 247; /* Broadcast address is 0 (MODBUS_BROADCAST_ADDRESS) */ if (slave >= 0 && slave <= max_slave) { ctx->slave = slave; } else { errno = EINVAL; return -1; } return 0; } /* Builds a RTU request header */ static int _modbus_rtu_build_request_basis( modbus_t *ctx, int function, int addr, int nb, uint8_t *req) { assert(ctx->slave != -1); req[0] = ctx->slave; req[1] = function; req[2] = addr >> 8; req[3] = addr & 0x00ff; req[4] = nb >> 8; req[5] = nb & 0x00ff; return _MODBUS_RTU_PRESET_REQ_LENGTH; } /* Builds a RTU response header */ static int _modbus_rtu_build_response_basis(sft_t *sft, uint8_t *rsp) { /* In this case, the slave is certainly valid because a check is already * done in _modbus_rtu_listen */ rsp[0] = sft->slave; rsp[1] = sft->function; return _MODBUS_RTU_PRESET_RSP_LENGTH; } static uint16_t crc16(uint8_t *buffer, uint16_t buffer_length) { uint8_t crc_hi = 0xFF; /* high CRC byte initialized */ uint8_t crc_lo = 0xFF; /* low CRC byte initialized */ unsigned int i; /* will index into CRC lookup */ /* pass through message buffer */ while (buffer_length--) { i = crc_lo ^ *buffer++; /* calculate the CRC */ crc_lo = crc_hi ^ table_crc_hi[i]; crc_hi = table_crc_lo[i]; } return (crc_hi << 8 | crc_lo); } static int _modbus_rtu_prepare_response_tid(const uint8_t *req, int *req_length) { (*req_length) -= _MODBUS_RTU_CHECKSUM_LENGTH; /* No TID */ return 0; } static int _modbus_rtu_send_msg_pre(uint8_t *req, int req_length) { uint16_t crc = crc16(req, req_length); /* According to the MODBUS specs (p. 14), the low order byte of the CRC comes * first in the RTU message */ req[req_length++] = crc & 0x00FF; req[req_length++] = crc >> 8; return req_length; } #if defined(_WIN32) /* This simple implementation is sort of a substitute of the select() call, * working this way: the win32_ser_select() call tries to read some data from * the serial port, setting the timeout as the select() call would. Data read is * stored into the receive buffer, that is then consumed by the win32_ser_read() * call. So win32_ser_select() does both the event waiting and the reading, * while win32_ser_read() only consumes the receive buffer. */ static void win32_ser_init(struct win32_ser *ws) { /* Clear everything */ memset(ws, 0x00, sizeof(struct win32_ser)); /* Set file handle to invalid */ ws->fd = INVALID_HANDLE_VALUE; } /* FIXME Try to remove length_to_read -> max_len argument, only used by win32 */ static int win32_ser_select(struct win32_ser *ws, int max_len, const struct timeval *tv) { COMMTIMEOUTS comm_to; unsigned int msec = 0; /* Check if some data still in the buffer to be consumed */ if (ws->n_bytes > 0) { return 1; } /* Setup timeouts like select() would do. FIXME Please someone on Windows can look at this? Does it possible to use WaitCommEvent? When tv is NULL, MAXDWORD isn't infinite! */ if (tv == NULL) { msec = MAXDWORD; } else { msec = tv->tv_sec * 1000 + tv->tv_usec / 1000; if (msec < 1) msec = 1; } comm_to.ReadIntervalTimeout = msec; comm_to.ReadTotalTimeoutMultiplier = 0; comm_to.ReadTotalTimeoutConstant = msec; comm_to.WriteTotalTimeoutMultiplier = 0; comm_to.WriteTotalTimeoutConstant = 1000; SetCommTimeouts(ws->fd, &comm_to); /* Read some bytes */ if ((max_len > PY_BUF_SIZE) || (max_len < 0)) { max_len = PY_BUF_SIZE; } if (ReadFile(ws->fd, &ws->buf, max_len, &ws->n_bytes, NULL)) { /* Check if some bytes available */ if (ws->n_bytes > 0) { /* Some bytes read */ return 1; } else { /* Just timed out */ return 0; } } else { /* Some kind of error */ return -1; } } static int win32_ser_read(struct win32_ser *ws, uint8_t *p_msg, unsigned int max_len) { unsigned int n = ws->n_bytes; if (max_len < n) { n = max_len; } if (n > 0) { memcpy(p_msg, ws->buf, n); } ws->n_bytes -= n; return n; } #endif #if HAVE_DECL_TIOCM_RTS static void _modbus_rtu_ioctl_rts(modbus_t *ctx, int on) { int fd = ctx->s; int flags; ioctl(fd, TIOCMGET, &flags); if (on) { flags |= TIOCM_RTS; } else { flags &= ~TIOCM_RTS; } ioctl(fd, TIOCMSET, &flags); } #endif static ssize_t _modbus_rtu_send(modbus_t *ctx, const uint8_t *req, int req_length) { #if defined(_WIN32) modbus_rtu_t *ctx_rtu = ctx->backend_data; DWORD n_bytes = 0; return (WriteFile(ctx_rtu->w_ser.fd, req, req_length, &n_bytes, NULL)) ? (ssize_t) n_bytes : -1; #else #if HAVE_DECL_TIOCM_RTS modbus_rtu_t *ctx_rtu = ctx->backend_data; if (ctx_rtu->rts != MODBUS_RTU_RTS_NONE) { ssize_t size; if (ctx->debug) { fprintf(stderr, "Sending request using RTS signal\n"); } ctx_rtu->set_rts(ctx, ctx_rtu->rts == MODBUS_RTU_RTS_UP); usleep(ctx_rtu->rts_delay); size = write(ctx->s, req, req_length); usleep(ctx_rtu->onebyte_time * req_length + ctx_rtu->rts_delay); ctx_rtu->set_rts(ctx, ctx_rtu->rts != MODBUS_RTU_RTS_UP); return size; } else { #endif return write(ctx->s, req, req_length); #if HAVE_DECL_TIOCM_RTS } #endif #endif } static int _modbus_rtu_receive(modbus_t *ctx, uint8_t *req) { int rc; modbus_rtu_t *ctx_rtu = ctx->backend_data; if (ctx_rtu->confirmation_to_ignore) { _modbus_receive_msg(ctx, req, MSG_CONFIRMATION); /* Ignore errors and reset the flag */ ctx_rtu->confirmation_to_ignore = FALSE; rc = 0; if (ctx->debug) { printf("Confirmation to ignore\n"); } } else { rc = _modbus_receive_msg(ctx, req, MSG_INDICATION); if (rc == 0) { /* The next expected message is a confirmation to ignore */ ctx_rtu->confirmation_to_ignore = TRUE; } } return rc; } static ssize_t _modbus_rtu_recv(modbus_t *ctx, uint8_t *rsp, int rsp_length) { #if defined(_WIN32) return win32_ser_read(&((modbus_rtu_t *) ctx->backend_data)->w_ser, rsp, rsp_length); #else return read(ctx->s, rsp, rsp_length); #endif } static int _modbus_rtu_flush(modbus_t *); static int _modbus_rtu_pre_check_confirmation(modbus_t *ctx, const uint8_t *req, const uint8_t *rsp, int rsp_length) { /* Check responding slave is the slave we requested (except for broacast * request) */ if (req[0] != rsp[0] && req[0] != MODBUS_BROADCAST_ADDRESS) { if (ctx->debug) { fprintf(stderr, "The responding slave %d isn't the requested slave %d\n", rsp[0], req[0]); } errno = EMBBADSLAVE; return -1; } else { return 0; } } /* The check_crc16 function shall return 0 if the message is ignored and the message length if the CRC is valid. Otherwise it shall return -1 and set errno to EMBBADCRC. */ static int _modbus_rtu_check_integrity(modbus_t *ctx, uint8_t *msg, const int msg_length) { uint16_t crc_calculated; uint16_t crc_received; int slave = msg[0]; /* Filter on the Modbus unit identifier (slave) in RTU mode to avoid useless * CRC computing. */ if (slave != ctx->slave && slave != MODBUS_BROADCAST_ADDRESS) { if (ctx->debug) { printf("Request for slave %d ignored (not %d)\n", slave, ctx->slave); } /* Following call to check_confirmation handles this error */ return 0; } crc_calculated = crc16(msg, msg_length - 2); crc_received = (msg[msg_length - 1] << 8) | msg[msg_length - 2]; /* Check CRC of msg */ if (crc_calculated == crc_received) { return msg_length; } else { if (ctx->debug) { fprintf(stderr, "ERROR CRC received 0x%0X != CRC calculated 0x%0X\n", crc_received, crc_calculated); } if (ctx->error_recovery & MODBUS_ERROR_RECOVERY_PROTOCOL) { _modbus_rtu_flush(ctx); } errno = EMBBADCRC; return -1; } } /* Sets up a serial port for RTU communications */ #if defined(_WIN32) static int _modbus_rtu_connect(modbus_t *ctx) { DCB dcb; modbus_rtu_t *ctx_rtu = ctx->backend_data; if (ctx->debug) { printf("Opening %s at %d bauds (%c, %d, %d)\n", ctx_rtu->device, ctx_rtu->baud, ctx_rtu->parity, ctx_rtu->data_bit, ctx_rtu->stop_bit); } /* Some references here: * http://msdn.microsoft.com/en-us/library/aa450602.aspx */ win32_ser_init(&ctx_rtu->w_ser); /* ctx_rtu->device should contain a string like "COMxx:" xx being a decimal * number */ ctx_rtu->w_ser.fd = CreateFileA( ctx_rtu->device, GENERIC_READ | GENERIC_WRITE, 0, NULL, OPEN_EXISTING, 0, NULL); /* Error checking */ if (ctx_rtu->w_ser.fd == INVALID_HANDLE_VALUE) { if (ctx->debug) { fprintf(stderr, "ERROR Can't open the device %s (LastError %d)\n", ctx_rtu->device, (int) GetLastError()); } return -1; } /* Save params */ ctx_rtu->old_dcb.DCBlength = sizeof(DCB); if (!GetCommState(ctx_rtu->w_ser.fd, &ctx_rtu->old_dcb)) { if (ctx->debug) { fprintf(stderr, "ERROR Error getting configuration (LastError %d)\n", (int) GetLastError()); } CloseHandle(ctx_rtu->w_ser.fd); ctx_rtu->w_ser.fd = INVALID_HANDLE_VALUE; return -1; } /* Build new configuration (starting from current settings) */ dcb = ctx_rtu->old_dcb; /* Speed setting */ dcb.BaudRate = ctx_rtu->baud; /* Data bits */ switch (ctx_rtu->data_bit) { case 5: dcb.ByteSize = 5; break; case 6: dcb.ByteSize = 6; break; case 7: dcb.ByteSize = 7; break; case 8: default: dcb.ByteSize = 8; break; } /* Stop bits */ if (ctx_rtu->stop_bit == 1) dcb.StopBits = ONESTOPBIT; else /* 2 */ dcb.StopBits = TWOSTOPBITS; /* Parity */ if (ctx_rtu->parity == 'N') { dcb.Parity = NOPARITY; dcb.fParity = FALSE; } else if (ctx_rtu->parity == 'E') { dcb.Parity = EVENPARITY; dcb.fParity = TRUE; } else { /* odd */ dcb.Parity = ODDPARITY; dcb.fParity = TRUE; } /* Hardware handshaking left as default settings retrieved */ /* No software handshaking */ dcb.fTXContinueOnXoff = TRUE; dcb.fOutX = FALSE; dcb.fInX = FALSE; /* Binary mode (it's the only supported on Windows anyway) */ dcb.fBinary = TRUE; /* Don't want errors to be blocking */ dcb.fAbortOnError = FALSE; /* Setup port */ if (!SetCommState(ctx_rtu->w_ser.fd, &dcb)) { if (ctx->debug) { fprintf(stderr, "ERROR Error setting new configuration (LastError %d)\n", (int) GetLastError()); } CloseHandle(ctx_rtu->w_ser.fd); ctx_rtu->w_ser.fd = INVALID_HANDLE_VALUE; return -1; } return 0; } #else static speed_t _get_termios_speed(int baud, int debug) { speed_t speed; switch (baud) { case 110: speed = B110; break; case 300: speed = B300; break; case 600: speed = B600; break; case 1200: speed = B1200; break; case 2400: speed = B2400; break; case 4800: speed = B4800; break; case 9600: speed = B9600; break; case 19200: speed = B19200; break; case 38400: speed = B38400; break; #ifdef B57600 case 57600: speed = B57600; break; #endif #ifdef B115200 case 115200: speed = B115200; break; #endif #ifdef B230400 case 230400: speed = B230400; break; #endif #ifdef B460800 case 460800: speed = B460800; break; #endif #ifdef B500000 case 500000: speed = B500000; break; #endif #ifdef B576000 case 576000: speed = B576000; break; #endif #ifdef B921600 case 921600: speed = B921600; break; #endif #ifdef B1000000 case 1000000: speed = B1000000; break; #endif #ifdef B1152000 case 1152000: speed = B1152000; break; #endif #ifdef B1500000 case 1500000: speed = B1500000; break; #endif #ifdef B2500000 case 2500000: speed = B2500000; break; #endif #ifdef B3000000 case 3000000: speed = B3000000; break; #endif #ifdef B3500000 case 3500000: speed = B3500000; break; #endif #ifdef B4000000 case 4000000: speed = B4000000; break; #endif default: speed = B9600; if (debug) { fprintf(stderr, "WARNING Unknown baud rate %d (B9600 used)\n", baud); } } return speed; } /* POSIX */ static int _modbus_rtu_connect(modbus_t *ctx) { struct termios tios; int flags; speed_t speed; modbus_rtu_t *ctx_rtu = ctx->backend_data; if (ctx->debug) { printf("Opening %s at %d bauds (%c, %d, %d)\n", ctx_rtu->device, ctx_rtu->baud, ctx_rtu->parity, ctx_rtu->data_bit, ctx_rtu->stop_bit); } /* The O_NOCTTY flag tells UNIX that this program doesn't want to be the "controlling terminal" for that port. If you don't specify this then any input (such as keyboard abort signals and so forth) will affect your process Timeouts are ignored in canonical input mode or when the NDELAY option is set on the file via open or fcntl */ flags = O_RDWR | O_NOCTTY | O_NDELAY | O_EXCL; #ifdef O_CLOEXEC flags |= O_CLOEXEC; #endif ctx->s = open(ctx_rtu->device, flags); if (ctx->s < 0) { if (ctx->debug) { fprintf(stderr, "ERROR Can't open the device %s (%s)\n", ctx_rtu->device, strerror(errno)); } return -1; } /* Save */ tcgetattr(ctx->s, &ctx_rtu->old_tios); memset(&tios, 0, sizeof(struct termios)); /* C_ISPEED Input baud (new interface) C_OSPEED Output baud (new interface) */ /* Set the baud rate */ /* On MacOS, constants of baud rates are equal to the integer in argument but that's not the case under Linux so we have to find the corresponding constant. Until the code is upgraded to termios2, the list of possible values is limited (no 14400 for example). */ if (9600 == B9600) { speed = ctx_rtu->baud; } else { speed = _get_termios_speed(ctx_rtu->baud, ctx->debug); } if ((cfsetispeed(&tios, speed) < 0) || (cfsetospeed(&tios, speed) < 0)) { close(ctx->s); ctx->s = -1; return -1; } /* C_CFLAG Control options CLOCAL Local line - do not change "owner" of port CREAD Enable receiver */ tios.c_cflag |= (CREAD | CLOCAL); /* CSIZE, HUPCL, CRTSCTS (hardware flow control) */ /* Set data bits (5, 6, 7, 8 bits) CSIZE Bit mask for data bits */ tios.c_cflag &= ~CSIZE; switch (ctx_rtu->data_bit) { case 5: tios.c_cflag |= CS5; break; case 6: tios.c_cflag |= CS6; break; case 7: tios.c_cflag |= CS7; break; case 8: default: tios.c_cflag |= CS8; break; } /* Stop bit (1 or 2) */ if (ctx_rtu->stop_bit == 1) tios.c_cflag &= ~CSTOPB; else /* 2 */ tios.c_cflag |= CSTOPB; /* PARENB Enable parity bit PARODD Use odd parity instead of even */ if (ctx_rtu->parity == 'N') { /* None */ tios.c_cflag &= ~PARENB; } else if (ctx_rtu->parity == 'E') { /* Even */ tios.c_cflag |= PARENB; tios.c_cflag &= ~PARODD; } else { /* Odd */ tios.c_cflag |= PARENB; tios.c_cflag |= PARODD; } /* Read the man page of termios if you need more information. */ /* This field isn't used on POSIX systems tios.c_line = 0; */ /* C_LFLAG Line options ISIG Enable SIGINTR, SIGSUSP, SIGDSUSP, and SIGQUIT signals ICANON Enable canonical input (else raw) XCASE Map uppercase \lowercase (obsolete) ECHO Enable echoing of input characters ECHOE Echo erase character as BS-SP-BS ECHOK Echo NL after kill character ECHONL Echo NL NOFLSH Disable flushing of input buffers after interrupt or quit characters IEXTEN Enable extended functions ECHOCTL Echo control characters as ^char and delete as ~? ECHOPRT Echo erased character as character erased ECHOKE BS-SP-BS entire line on line kill FLUSHO Output being flushed PENDIN Retype pending input at next read or input char TOSTOP Send SIGTTOU for background output Canonical input is line-oriented. Input characters are put into a buffer which can be edited interactively by the user until a CR (carriage return) or LF (line feed) character is received. Raw input is unprocessed. Input characters are passed through exactly as they are received, when they are received. Generally you'll deselect the ICANON, ECHO, ECHOE, and ISIG options when using raw input */ /* Raw input */ tios.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG); /* C_IFLAG Input options Constant Description INPCK Enable parity check IGNPAR Ignore parity errors PARMRK Mark parity errors ISTRIP Strip parity bits IXON Enable software flow control (outgoing) IXOFF Enable software flow control (incoming) IXANY Allow any character to start flow again IGNBRK Ignore break condition BRKINT Send a SIGINT when a break condition is detected INLCR Map NL to CR IGNCR Ignore CR ICRNL Map CR to NL IUCLC Map uppercase to lowercase IMAXBEL Echo BEL on input line too long */ if (ctx_rtu->parity == 'N') { /* None */ tios.c_iflag &= ~INPCK; } else { tios.c_iflag |= INPCK; } /* Software flow control is disabled */ tios.c_iflag &= ~(IXON | IXOFF | IXANY); /* C_OFLAG Output options OPOST Postprocess output (not set = raw output) ONLCR Map NL to CR-NL ONCLR ant others needs OPOST to be enabled */ /* Raw output */ tios.c_oflag &= ~OPOST; /* C_CC Control characters VMIN Minimum number of characters to read VTIME Time to wait for data (tenths of seconds) UNIX serial interface drivers provide the ability to specify character and packet timeouts. Two elements of the c_cc array are used for timeouts: VMIN and VTIME. Timeouts are ignored in canonical input mode or when the NDELAY option is set on the file via open or fcntl. VMIN specifies the minimum number of characters to read. If it is set to 0, then the VTIME value specifies the time to wait for every character read. Note that this does not mean that a read call for N bytes will wait for N characters to come in. Rather, the timeout will apply to the first character and the read call will return the number of characters immediately available (up to the number you request). If VMIN is non-zero, VTIME specifies the time to wait for the first character read. If a character is read within the time given, any read will block (wait) until all VMIN characters are read. That is, once the first character is read, the serial interface driver expects to receive an entire packet of characters (VMIN bytes total). If no character is read within the time allowed, then the call to read returns 0. This method allows you to tell the serial driver you need exactly N bytes and any read call will return 0 or N bytes. However, the timeout only applies to the first character read, so if for some reason the driver misses one character inside the N byte packet then the read call could block forever waiting for additional input characters. VTIME specifies the amount of time to wait for incoming characters in tenths of seconds. If VTIME is set to 0 (the default), reads will block (wait) indefinitely unless the NDELAY option is set on the port with open or fcntl. */ /* Unused because we use open with the NDELAY option */ tios.c_cc[VMIN] = 0; tios.c_cc[VTIME] = 0; if (tcsetattr(ctx->s, TCSANOW, &tios) < 0) { close(ctx->s); ctx->s = -1; return -1; } return 0; } #endif // FIXME Temporary solution before rewriting Windows RTU backend static unsigned int _modbus_rtu_is_connected(modbus_t *ctx) { #if defined(_WIN32) modbus_rtu_t *ctx_rtu = ctx->backend_data; /* Check if file handle is valid */ return ctx_rtu->w_ser.fd != INVALID_HANDLE_VALUE; #else return ctx->s >= 0; #endif } int modbus_rtu_set_serial_mode(modbus_t *ctx, int mode) { if (ctx == NULL) { errno = EINVAL; return -1; } if (ctx->backend->backend_type == _MODBUS_BACKEND_TYPE_RTU) { #if HAVE_DECL_TIOCSRS485 modbus_rtu_t *ctx_rtu = ctx->backend_data; struct serial_rs485 rs485conf; if (mode == MODBUS_RTU_RS485) { // Get if (ioctl(ctx->s, TIOCGRS485, &rs485conf) < 0) { return -1; } // Set rs485conf.flags |= SER_RS485_ENABLED; if (ioctl(ctx->s, TIOCSRS485, &rs485conf) < 0) { return -1; } ctx_rtu->serial_mode = MODBUS_RTU_RS485; return 0; } else if (mode == MODBUS_RTU_RS232) { /* Turn off RS485 mode only if required */ if (ctx_rtu->serial_mode == MODBUS_RTU_RS485) { /* The ioctl call is avoided because it can fail on some RS232 ports */ if (ioctl(ctx->s, TIOCGRS485, &rs485conf) < 0) { return -1; } rs485conf.flags &= ~SER_RS485_ENABLED; if (ioctl(ctx->s, TIOCSRS485, &rs485conf) < 0) { return -1; } } ctx_rtu->serial_mode = MODBUS_RTU_RS232; return 0; } #else if (ctx->debug) { fprintf(stderr, "This function isn't supported on your platform\n"); } errno = ENOTSUP; return -1; #endif } /* Wrong backend and invalid mode specified */ errno = EINVAL; return -1; } int modbus_rtu_get_serial_mode(modbus_t *ctx) { if (ctx == NULL) { errno = EINVAL; return -1; } if (ctx->backend->backend_type == _MODBUS_BACKEND_TYPE_RTU) { #if HAVE_DECL_TIOCSRS485 modbus_rtu_t *ctx_rtu = ctx->backend_data; return ctx_rtu->serial_mode; #else if (ctx->debug) { fprintf(stderr, "This function isn't supported on your platform\n"); } errno = ENOTSUP; return -1; #endif } else { errno = EINVAL; return -1; } } int modbus_rtu_get_rts(modbus_t *ctx) { if (ctx == NULL) { errno = EINVAL; return -1; } if (ctx->backend->backend_type == _MODBUS_BACKEND_TYPE_RTU) { #if HAVE_DECL_TIOCM_RTS modbus_rtu_t *ctx_rtu = ctx->backend_data; return ctx_rtu->rts; #else if (ctx->debug) { fprintf(stderr, "This function isn't supported on your platform\n"); } errno = ENOTSUP; return -1; #endif } else { errno = EINVAL; return -1; } } int modbus_rtu_set_rts(modbus_t *ctx, int mode) { if (ctx == NULL) { errno = EINVAL; return -1; } if (ctx->backend->backend_type == _MODBUS_BACKEND_TYPE_RTU) { #if HAVE_DECL_TIOCM_RTS modbus_rtu_t *ctx_rtu = ctx->backend_data; if (mode == MODBUS_RTU_RTS_NONE || mode == MODBUS_RTU_RTS_UP || mode == MODBUS_RTU_RTS_DOWN) { ctx_rtu->rts = mode; /* Set the RTS bit in order to not reserve the RS485 bus */ ctx_rtu->set_rts(ctx, ctx_rtu->rts != MODBUS_RTU_RTS_UP); return 0; } else { errno = EINVAL; return -1; } #else if (ctx->debug) { fprintf(stderr, "This function isn't supported on your platform\n"); } errno = ENOTSUP; return -1; #endif } /* Wrong backend or invalid mode specified */ errno = EINVAL; return -1; } int modbus_rtu_set_custom_rts(modbus_t *ctx, void (*set_rts)(modbus_t *ctx, int on)) { if (ctx == NULL) { errno = EINVAL; return -1; } if (ctx->backend->backend_type == _MODBUS_BACKEND_TYPE_RTU) { #if HAVE_DECL_TIOCM_RTS modbus_rtu_t *ctx_rtu = ctx->backend_data; ctx_rtu->set_rts = set_rts; return 0; #else if (ctx->debug) { fprintf(stderr, "This function isn't supported on your platform\n"); } errno = ENOTSUP; return -1; #endif } else { errno = EINVAL; return -1; } } int modbus_rtu_get_rts_delay(modbus_t *ctx) { if (ctx == NULL) { errno = EINVAL; return -1; } if (ctx->backend->backend_type == _MODBUS_BACKEND_TYPE_RTU) { #if HAVE_DECL_TIOCM_RTS modbus_rtu_t *ctx_rtu; ctx_rtu = (modbus_rtu_t *) ctx->backend_data; return ctx_rtu->rts_delay; #else if (ctx->debug) { fprintf(stderr, "This function isn't supported on your platform\n"); } errno = ENOTSUP; return -1; #endif } else { errno = EINVAL; return -1; } } int modbus_rtu_set_rts_delay(modbus_t *ctx, int us) { if (ctx == NULL || us < 0) { errno = EINVAL; return -1; } if (ctx->backend->backend_type == _MODBUS_BACKEND_TYPE_RTU) { #if HAVE_DECL_TIOCM_RTS modbus_rtu_t *ctx_rtu; ctx_rtu = (modbus_rtu_t *) ctx->backend_data; ctx_rtu->rts_delay = us; return 0; #else if (ctx->debug) { fprintf(stderr, "This function isn't supported on your platform\n"); } errno = ENOTSUP; return -1; #endif } else { errno = EINVAL; return -1; } } static void _modbus_rtu_close(modbus_t *ctx) { /* Restore line settings and close file descriptor in RTU mode */ modbus_rtu_t *ctx_rtu = ctx->backend_data; #if defined(_WIN32) /* Revert settings */ if (!SetCommState(ctx_rtu->w_ser.fd, &ctx_rtu->old_dcb) && ctx->debug) { fprintf(stderr, "ERROR Couldn't revert to configuration (LastError %d)\n", (int) GetLastError()); } if (!CloseHandle(ctx_rtu->w_ser.fd) && ctx->debug) { fprintf(stderr, "ERROR Error while closing handle (LastError %d)\n", (int) GetLastError()); } #else if (ctx->s >= 0) { tcsetattr(ctx->s, TCSANOW, &ctx_rtu->old_tios); close(ctx->s); ctx->s = -1; } #endif } static int _modbus_rtu_flush(modbus_t *ctx) { #if defined(_WIN32) modbus_rtu_t *ctx_rtu = ctx->backend_data; ctx_rtu->w_ser.n_bytes = 0; return (PurgeComm(ctx_rtu->w_ser.fd, PURGE_RXCLEAR) == FALSE); #else return tcflush(ctx->s, TCIOFLUSH); #endif } static int _modbus_rtu_select(modbus_t *ctx, fd_set *rset, struct timeval *tv, int length_to_read) { int s_rc; #if defined(_WIN32) s_rc = win32_ser_select( &((modbus_rtu_t *) ctx->backend_data)->w_ser, length_to_read, tv); if (s_rc == 0) { errno = ETIMEDOUT; return -1; } if (s_rc < 0) { return -1; } #else while ((s_rc = select(ctx->s + 1, rset, NULL, NULL, tv)) == -1) { if (errno == EINTR) { if (ctx->debug) { fprintf(stderr, "A non blocked signal was caught\n"); } /* Necessary after an error */ FD_ZERO(rset); FD_SET(ctx->s, rset); } else { return -1; } } if (s_rc == 0) { /* Timeout */ errno = ETIMEDOUT; return -1; } #endif return s_rc; } static void _modbus_rtu_free(modbus_t *ctx) { if (ctx->backend_data) { free(((modbus_rtu_t *) ctx->backend_data)->device); free(ctx->backend_data); } free(ctx); } // clang-format off const modbus_backend_t _modbus_rtu_backend = { _MODBUS_BACKEND_TYPE_RTU, _MODBUS_RTU_HEADER_LENGTH, _MODBUS_RTU_CHECKSUM_LENGTH, MODBUS_RTU_MAX_ADU_LENGTH, _modbus_set_slave, _modbus_rtu_build_request_basis, _modbus_rtu_build_response_basis, _modbus_rtu_prepare_response_tid, _modbus_rtu_send_msg_pre, _modbus_rtu_send, _modbus_rtu_receive, _modbus_rtu_recv, _modbus_rtu_check_integrity, _modbus_rtu_pre_check_confirmation, _modbus_rtu_connect, _modbus_rtu_is_connected, _modbus_rtu_close, _modbus_rtu_flush, _modbus_rtu_select, _modbus_rtu_free }; // clang-format on modbus_t * modbus_new_rtu(const char *device, int baud, char parity, int data_bit, int stop_bit) { modbus_t *ctx; modbus_rtu_t *ctx_rtu; /* Check device argument */ if (device == NULL || *device == 0) { fprintf(stderr, "The device string is empty\n"); errno = EINVAL; return NULL; } /* Check baud argument */ if (baud == 0) { fprintf(stderr, "The baud rate value must not be zero\n"); errno = EINVAL; return NULL; } ctx = (modbus_t *) malloc(sizeof(modbus_t)); if (ctx == NULL) { return NULL; } _modbus_init_common(ctx); ctx->backend = &_modbus_rtu_backend; ctx->backend_data = (modbus_rtu_t *) malloc(sizeof(modbus_rtu_t)); if (ctx->backend_data == NULL) { modbus_free(ctx); errno = ENOMEM; return NULL; } ctx_rtu = (modbus_rtu_t *) ctx->backend_data; /* Device name and \0 */ ctx_rtu->device = (char *) malloc((strlen(device) + 1) * sizeof(char)); if (ctx_rtu->device == NULL) { modbus_free(ctx); errno = ENOMEM; return NULL; } #if defined(_WIN32) strcpy_s(ctx_rtu->device, strlen(device) + 1, device); #else strcpy(ctx_rtu->device, device); #endif ctx_rtu->baud = baud; if (parity == 'N' || parity == 'E' || parity == 'O') { ctx_rtu->parity = parity; } else { modbus_free(ctx); errno = EINVAL; return NULL; } ctx_rtu->data_bit = data_bit; ctx_rtu->stop_bit = stop_bit; #if HAVE_DECL_TIOCSRS485 /* The RS232 mode has been set by default */ ctx_rtu->serial_mode = MODBUS_RTU_RS232; #endif #if HAVE_DECL_TIOCM_RTS /* The RTS use has been set by default */ ctx_rtu->rts = MODBUS_RTU_RTS_NONE; /* Calculate estimated time in micro second to send one byte */ ctx_rtu->onebyte_time = 1000000 * (1 + data_bit + (parity == 'N' ? 0 : 1) + stop_bit) / baud; /* The internal function is used by default to set RTS */ ctx_rtu->set_rts = _modbus_rtu_ioctl_rts; /* The delay before and after transmission when toggling the RTS pin */ ctx_rtu->rts_delay = ctx_rtu->onebyte_time; #endif ctx_rtu->confirmation_to_ignore = FALSE; return ctx; }