QT PLC 通过ModBus_RTU 串口通信

/* * Copyright © 2001-2011 Stéphane Raimbault <[email protected]> * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * This library is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA * * * This library implements the Modbus protocol. * http://libmodbus.org/ */ #include <stdio.h> #include <string.h> #include <stdlib.h> #include <errno.h> #include <limits.h> #include <time.h> #include "config.h" #include "modbus.h" #include "modbus-private.h" #pragma comment(lib, "ws2_32.lib") /* Internal use */ #define MSG_LENGTH_UNDEFINED -1 /* Exported version */ const unsigned int libmodbus_version_major = LIBMODBUS_VERSION_MAJOR; const unsigned int libmodbus_version_minor = LIBMODBUS_VERSION_MINOR; const unsigned int libmodbus_version_micro = LIBMODBUS_VERSION_MICRO; /* Max between RTU and TCP max adu length (so TCP) */ #define MAX_MESSAGE_LENGTH 260 /* 3 steps are used to parse the query */ typedef enum { _STEP_FUNCTION, _STEP_META, _STEP_DATA } _step_t; const char *modbus_strerror(int errnum) { switch (errnum) { case EMBXILFUN: return "Illegal function"; case EMBXILADD: return "Illegal data address"; case EMBXILVAL: return "Illegal data value"; case EMBXSFAIL: return "Slave device or server failure"; case EMBXACK: return "Acknowledge"; case EMBXSBUSY: return "Slave device or server is busy"; case EMBXNACK: return "Negative acknowledge"; case EMBXMEMPAR: return "Memory parity error"; case EMBXGPATH: return "Gateway path unavailable"; case EMBXGTAR: return "Target device failed to respond"; case EMBBADCRC: return "Invalid CRC"; case EMBBADDATA: return "Invalid data"; case EMBBADEXC: return "Invalid exception code"; case EMBMDATA: return "Too many data"; default: return strerror(errnum); } } void _error_print(modbus_t *ctx, const char *context) { if (ctx->debug) { fprintf(stderr, "ERROR %s", modbus_strerror(errno)); if (context != NULL) { fprintf(stderr, ": %s\n", context); } else { fprintf(stderr, "\n"); } } } int _sleep_and_flush(modbus_t *ctx) { #ifdef _WIN32 /* usleep doesn't exist on Windows */ Sleep((ctx->response_timeout.tv_sec * 1000) + (ctx->response_timeout.tv_usec / 1000)); #else /* usleep source code */ struct timespec request, remaining; request.tv_sec = ctx->response_timeout.tv_sec; request.tv_nsec = ((long int)ctx->response_timeout.tv_usec % 1000000) * 1000; while (nanosleep(&request, &remaining) == -1 && errno == EINTR) request = remaining; #endif return modbus_flush(ctx); } int modbus_flush(modbus_t *ctx) { int rc = ctx->backend->flush(ctx); if (rc != -1 && ctx->debug) { printf("%d bytes flushed\n", rc); } return rc; } /* Computes the length of the expected response */ static unsigned int compute_response_length_from_request(modbus_t *ctx, uint8_t *req) { int length; const int offset = ctx->backend->header_length; switch (req[offset]) { case _FC_READ_COILS: case _FC_READ_DISCRETE_INPUTS: { /* Header + nb values (code from write_bits) */ int nb = (req[offset + 3] << 8) | req[offset + 4]; length = 2 + (nb / 8) + ((nb % 8) ? 1 : 0); } break; case _FC_WRITE_AND_READ_REGISTERS: case _FC_READ_HOLDING_REGISTERS: case _FC_READ_INPUT_REGISTERS: /* Header + 2 * nb values */ length = 2 + 2 * (req[offset + 3] << 8 | req[offset + 4]); break; case _FC_READ_EXCEPTION_STATUS: length = 3; break; case _FC_REPORT_SLAVE_ID: /* The response is device specific (the header provides the length) */ return MSG_LENGTH_UNDEFINED; default: length = 5; } return offset + length + ctx->backend->checksum_length; } /* Sends a request/response */ static int send_msg(modbus_t *ctx, uint8_t *msg, int msg_length) { int rc; int i; msg_length = ctx->backend->send_msg_pre(msg, msg_length); if (ctx->debug) { for (i = 0; i < msg_length; i++) printf("[%.2X]", msg[i]); printf("\n"); } /* In recovery mode, the write command will be issued until to be successful! Disabled by default. */ do { rc = ctx->backend->send(ctx, msg, msg_length); if (rc == -1) { _error_print(ctx, NULL); if (ctx->error_recovery & MODBUS_ERROR_RECOVERY_LINK) { int saved_errno = errno; if ((errno == EBADF || errno == ECONNRESET || errno == EPIPE)) { modbus_close(ctx); modbus_connect(ctx); } else { _sleep_and_flush(ctx); } errno = saved_errno; } } } while ((ctx->error_recovery & MODBUS_ERROR_RECOVERY_LINK) && rc == -1); if (rc > 0 && rc != msg_length) { errno = EMBBADDATA; return -1; } return rc; } int modbus_send_raw_request(modbus_t *ctx, uint8_t *raw_req, int raw_req_length) { sft_t sft; uint8_t req[MAX_MESSAGE_LENGTH]; int req_length; if (raw_req_length < 2) { /* The raw request must contain function and slave at least */ errno = EINVAL; return -1; } sft.slave = raw_req[0]; sft.function = raw_req[1]; /* The t_id is left to zero */ sft.t_id = 0; /* This response function only set the header so it's convenient here */ req_length = ctx->backend->build_response_basis(&sft, req); if (raw_req_length > 2) { /* Copy data after function code */ memcpy(req + req_length, raw_req + 2, raw_req_length - 2); req_length += raw_req_length - 2; } return send_msg(ctx, req, req_length); } /* ---------- Request Indication ---------- | Client | ---------------------->| Server | ---------- Confirmation Response ---------- */ typedef enum { /* Request message on the server side */ MSG_INDICATION, /* Request message on the client side */ MSG_CONFIRMATION } msg_type_t; /* Computes the length to read after the function received */ static uint8_t compute_meta_length_after_function(int function, msg_type_t msg_type) { int length; if (msg_type == MSG_INDICATION) { if (function <= _FC_WRITE_SINGLE_REGISTER) { length = 4; } else if (function == _FC_WRITE_MULTIPLE_COILS || function == _FC_WRITE_MULTIPLE_REGISTERS) { length = 5; } else if (function == _FC_WRITE_AND_READ_REGISTERS) { length = 9; } else { /* _FC_READ_EXCEPTION_STATUS, _FC_REPORT_SLAVE_ID */ length = 0; } } else { /* MSG_CONFIRMATION */ switch (function) { case _FC_WRITE_SINGLE_COIL: case _FC_WRITE_SINGLE_REGISTER: case _FC_WRITE_MULTIPLE_COILS: case _FC_WRITE_MULTIPLE_REGISTERS: length = 4; break; default: length = 1; } } return length; } /* Computes the length to read after the meta information (address,