"# \u901a\u8fc7libmodbus\u5e93\u6d4b\u91cfModbus\u6570\u636e\u4f20\u8f93\u901f\u7387\u7684C\u7a0b\u5e8f\n\n> 2024-04-21 | 2024-04-21\n> https:\/\/www.modbus.cn\/en\/27696.html\n\n**Modbus\u7f16\u7a0b\u5f00\u53d1**\n\n---\n\n#### \u529f\u80fd\u6982\u8ff0\n\n\u8be5\u5de5\u5177\u65e8\u5728\u901a\u8fc7\u8fde\u7eed\u53d1\u9001Modbus\u8bf7\u6c42\u5e76\u8bb0\u5f55\u54cd\u5e94\u65f6\u95f4\u6765\u6d4b\u91cf\u6570\u636e\u4f20\u8f93\u901f\u7387\u3002\u5b83\u652f\u6301\u4e24\u79cd\u4e3b\u8981\u7684Modbus\u6a21\u5f0f\uff1aTCP\u548cRTU\uff0c\u7528\u6237\u53ef\u4ee5\u901a\u8fc7\u547d\u4ee4\u884c\u53c2\u6570\u9009\u62e9\u4f7f\u7528\u54ea\u79cd\u6a21\u5f0f\u8fdb\u884c\u6d4b\u8bd5\u3002\u8be5\u7a0b\u5e8f\u901a\u8fc7\u6d4b\u91cf\u5728\u6307\u5b9a\u65f6\u95f4\u5185\u6210\u529f\u8bfb\u53d6\u7684\u6570\u636e\u70b9\u6570\u91cf\u6765\u8ba1\u7b97\u6570\u636e\u4f20\u8f93\u901f\u7387\uff0c\u5e76\u5c06\u7ed3\u679c\u4ee5\u70b9\/\u79d2\u548cKiB\/\u79d2\u4e24\u79cd\u5355\u4f4d\u5c55\u793a\uff0c\u4e3a\u7528\u6237\u63d0\u4f9b\u4e86\u4e00\u79cd\u76f4\u89c2\u7684\u6027\u80fd\u6307\u6807\u3002\n\n```\n#include <stdio.h>\n#ifndef _MSC_VER\n#include <sys\/time.h>\n#include <unistd.h>\n#endif\n#include <errno.h>\n#include <stdlib.h>\n#include <string.h>\n#include <time.h>\n\n#include <modbus.h>\n\n#define G_MSEC_PER_SEC 1000\n\nstatic uint32_t gettime_ms(void)\n{\n    struct timeval tv;\n#if !defined(_MSC_VER)\n    gettimeofday(&tv, NULL);  \/\/ \u83b7\u53d6\u5f53\u524d\u65f6\u95f4\n    return (uint32_t) tv.tv_sec * 1000 + tv.tv_usec \/ 1000;\n#else\n    return GetTickCount();  \/\/ Windows\u4e0b\u4f7f\u7528GetTickCount\u83b7\u53d6\u65f6\u95f4\n#endif\n}\n\nenum {\n    TCP,\n    RTU\n};\n\n\/* \u4e3b\u51fd\u6570\u5f00\u59cb *\/\nint main(int argc, char *argv[])\n{\n    uint8_t *tab_bit;\n    uint16_t *tab_reg;\n    modbus_t *ctx;\n    int i;\n    int nb_points;\n    double elapsed;\n    uint32_t start;\n    uint32_t end;\n    uint32_t bytes;\n    uint32_t rate;\n    int rc;\n    int n_loop;\n    int use_backend;\n\n    \/\/ \u6839\u636e\u8f93\u5165\u53c2\u6570\u9009\u62e9\u540e\u7aef\uff08TCP\u6216RTU\uff09\u548c\u5faa\u73af\u6b21\u6570\n    if (argc > 1) {\n        if (strcmp(argv[1], \"tcp\") == 0) {\n            use_backend = TCP;\n            n_loop = 100000;\n        } else if (strcmp(argv[1], \"rtu\") == 0) {\n            use_backend = RTU;\n            n_loop = 100;\n        } else {\n            printf(\"Usage:\\n  %s [tcp|rtu] - Modbus client to measure data bandwidth\\n\\n\",\n                   argv[0]);\n            exit(1);\n        }\n    } else {\n        \/* \u9ed8\u8ba4\u4f7f\u7528TCP\u548c100000\u6b21\u5faa\u73af *\/\n        use_backend = TCP;\n        n_loop = 100000;\n    }\n\n    \/\/ \u521d\u59cb\u5316Modbus\u4e0a\u4e0b\u6587\n    if (use_backend == TCP) {\n        ctx = modbus_new_tcp(\"127.0.0.1\", 1502);\n    } else {\n        ctx = modbus_new_rtu(\"\/dev\/ttyUSB1\", 115200, 'N', 8, 1);\n        modbus_set_slave(ctx, 1);\n    }\n    if (modbus_connect(ctx) == -1) {\n        fprintf(stderr, \"Connection failed: %s\\n\", modbus_strerror(errno));\n        modbus_free(ctx);\n        return -1;\n    }\n\n    \/\/ \u5206\u914d\u5185\u5b58\u5b58\u50a8Modbus\u72b6\u6001\u548c\u5bc4\u5b58\u5668\n    tab_bit = (uint8_t *) malloc(MODBUS_MAX_READ_BITS * sizeof(uint8_t));\n    memset(tab_bit, 0, MODBUS_MAX_READ_BITS * sizeof(uint8_t));\n\n    tab_reg = (uint16_t *) malloc(MODBUS_MAX_READ_REGISTERS * sizeof(uint16_t));\n    memset(tab_reg, 0, MODBUS_MAX_READ_REGISTERS * sizeof(uint16_t));\n\n    \/\/ \u5f00\u59cb\u6d4b\u8bd5\u8bfb\u53d6\u4f4d\n    printf(\"READ BITS\\n\\n\");\n\n    nb_points = MODBUS_MAX_READ_BITS;\n    start = gettime_ms();\n    for (i = 0; i < n_loop; i++) {\n        rc = modbus_read_bits(ctx, 0, nb_points, tab_bit);\n        if (rc == -1) {\n            fprintf(stderr, \"%s\\n\", modbus_strerror(errno));\n            return -1;\n        }\n    }\n    end = gettime_ms();\n    elapsed = end - start;\n\n    \/\/ \u8ba1\u7b97\u5e76\u663e\u793a\u6570\u636e\u4f20\u8f93\u7387\n    rate = (n_loop * nb_points) * G_MSEC_PER_SEC \/ (end - start);\n    printf(\"Transfer rate in points\/seconds:\\n\");\n    printf(\"* %d points\/s\\n\", rate);\n    printf(\"\\n\");\n\n    \/\/ \u663e\u793a\u8bfb\u53d6\u7684\u603b\u5b57\u8282\u6570\u548c\u901f\u7387\n    bytes = n_loop * (nb_points \/ 8) + ((nb_points % 8) ? 1 : 0);\n    rate = bytes \/ 1024 * G_MSEC_PER_SEC \/ (end - start);\n    printf(\"Values:\\n\");\n    printf(\"* %d x %d values\\n\", n_loop, nb_points);\n    printf(\"* %.3f ms for %d bytes\\n\", elapsed, bytes);\n    printf(\"* %d KiB\/s\\n\", rate);\n    printf(\"\\n\");\n\n    \/\/ \u7c7b\u4f3c\u5730\uff0c\u8fdb\u884c\u5bc4\u5b58\u5668\u8bfb\u53d6\u6d4b\u8bd5\n    printf(\"READ REGISTERS\\n\\n\");\n\n    nb_points = MODBUS_MAX_READ_REGISTERS;\n    start = gettime_ms();\n    for (i = 0; i < n_loop; i++) {\n        rc = modbus_read_registers(ctx, 0, nb_points, tab_reg);\n        if (rc == -1) {\n            fprintf(stderr, \"%s\\n\", modbus_strerror(errno));\n            return -1;\n        }\n    }\n    end = gettime_ms();\n    elapsed = end - start;\n\n    rate = (n_loop * nb_points) * G_MSEC_PER_SEC \/ (end - start);\n    printf(\"Transfer rate in points\/seconds:\\n\");\n    printf(\"* %d registers\/s\\n\", rate);\n    printf(\"\\n\");\n\n    \/\/ \u8ba1\u7b97\u5bc4\u5b58\u5668\u8bfb\u53d6\u7684\u5b57\u8282\u6570\u548c\u901f\u7387\n    bytes = n_loop * nb_points * sizeof(uint16_t);\n    rate = bytes \/ 1024 * G_MSEC_PER_SEC \/ (end - start);\n    printf(\"Values:\\n\");\n    printf(\"* %d x %d values\\n\", n_loop, nb_points);\n    printf(\"* %.3f ms for %d bytes\\n\", elapsed, bytes);\n    printf(\"* %d KiB\/s\\n\", rate);\n    printf(\"\\n\");\n\n    \/\/ \u6d4b\u8bd5\u540c\u65f6\u5199\u5165\u548c\u8bfb\u53d6\u5bc4\u5b58\u5668\n    printf(\"WRITE AND READ REGISTERS\\n\\n\");\n\n    nb_points = MODBUS_MAX_WR_WRITE_REGISTERS;\n    start = gettime_ms();\n    for (i = 0; i < n_loop; i++) {\n        rc = modbus_write_and_read_registers(\n            ctx, 0, nb_points, tab_reg, 0, nb_points, tab_reg);\n        if (rc == -1) {\n            fprintf(stderr, \"%s\\n\", modbus_strerror(errno));\n            return -1;\n        }\n    }\n    end = gettime_ms();\n    elapsed = end - start;\n\n    rate = (n_loop * nb_points) * G_MSEC_PER_SEC \/ (end - start);\n    printf(\"Transfer rate in points\/seconds:\\n\");\n    printf(\"* %d registers\/s\\n\", rate);\n    printf(\"\\n\");\n\n    bytes = n_loop * nb_points * sizeof(uint16_t);\n    rate = bytes \/ 1024 * G_MSEC_PER_SEC \/ (end - start);\n    printf(\"Values:\\n\");\n    printf(\"* %d x %d values\\n\", n_loop, nb_points);\n    printf(\"* %.3f ms for %d bytes\\n\", elapsed, bytes);\n    printf(\"* %d KiB\/s\\n\", rate);\n    printf(\"\\n\");\n\n    \/\/ \u91ca\u653e\u5185\u5b58\uff0c\u5173\u95ed\u8fde\u63a5\n    free(tab_bit);\n    free(tab_reg);\n\n    modbus_close(ctx);\n    modbus_free(ctx);\n\n    return 0;\n}\n```\n\n#### \u7a0b\u5e8f\u7ed3\u6784\u4e0e\u5b9e\u73b0\n\n\u7a0b\u5e8f\u4e3b\u4f53\u5728`main`\u51fd\u6570\u4e2d\u5b9e\u73b0\uff0c\u6839\u636e\u7528\u6237\u8f93\u5165\u9009\u62e9\u6d4b\u8bd5\u7684\u540e\u7aef\uff08TCP\u6216RTU\uff09\u548c\u6267\u884c\u7684\u5faa\u73af\u6b21\u6570\u3002\u5bf9\u4e8eTCP\u8fde\u63a5\uff0c\u5b83\u5c1d\u8bd5\u8fde\u63a5\u5230\u672c\u5730\u4e3b\u673a\u4e0a\u7684\u7279\u5b9a\u7aef\u53e3\uff1b\u5bf9\u4e8eRTU\u6a21\u5f0f\uff0c\u5219\u901a\u8fc7\u4e32\u884c\u7aef\u53e3\u8fdb\u884c\u901a\u4fe1\u3002\u8fde\u63a5\u6210\u529f\u540e\uff0c\u7a0b\u5e8f\u5c06\u5206\u914d\u5185\u5b58\u4ee5\u5b58\u50a8Modbus\u72b6\u6001\u548c\u5bc4\u5b58\u5668\u503c\uff0c\u5e76\u5f00\u59cb\u6d4b\u8bd5\u5e8f\u5217\u3002\n\n\u6027\u80fd\u6d4b\u8bd5\u8fc7\u7a0b\n\n\u6d4b\u8bd5\u5305\u62ec\u4e09\u4e2a\u4e3b\u8981\u9636\u6bb5\uff1a\u8bfb\u53d6\u4f4d\u3001\u8bfb\u53d6\u5bc4\u5b58\u5668\u548c\u5199\u8bfb\u5bc4\u5b58\u5668\u3002\u5728\u6bcf\u4e2a\u9636\u6bb5\uff0c\u7a0b\u5e8f\u90fd\u4f1a\u6267\u884c\u5927\u91cf\u7684Modbus\u64cd\u4f5c\uff0c\u4ee5\u4fbf\u6536\u96c6\u8db3\u591f\u7684\u6570\u636e\u6765\u8fdb\u884c\u6709\u6548\u7684\u6027\u80fd\u5206\u6790\u3002\n\n- **\u8bfb\u53d6\u4f4d** - \u6d4b\u8bd5\u901a\u8fc7\u8fde\u7eed\u8bfb\u53d6Modbus\u4f4d\uff08\u6570\u5b57\u8f93\u5165\u548c\u8f93\u51fa\uff09\u6765\u8bc4\u4f30\u4f4d\u64cd\u4f5c\u7684\u6027\u80fd\u3002\n\n- **\u8bfb\u53d6\u5bc4\u5b58\u5668** - \u901a\u8fc7\u8fde\u7eed\u8bfb\u53d6Modbus\u5bc4\u5b58\u5668\uff08\u7c7b\u4f3c\u4e8e\u6a21\u62df\u8f93\u5165\u548c\u4fdd\u6301\u5bc4\u5b58\u5668\uff09\u6765\u6d4b\u8bd5\u5bc4\u5b58\u5668\u64cd\u4f5c\u7684\u6548\u7387\u3002\n\n- **\u5199\u8bfb\u5bc4\u5b58\u5668** - \u8fdb\u884c\u5199\u64cd\u4f5c\u540e\u7acb\u5373\u8bfb\u53d6\u5bc4\u5b58\u5668\uff0c\u4ee5\u6d4b\u8bd5\u7ec4\u5408\u64cd\u4f5c\u7684\u6027\u80fd\u3002\n\n\u6bcf\u6b21\u6d4b\u8bd5\u540e\uff0c\u7a0b\u5e8f\u90fd\u4f1a\u8ba1\u7b97\u5e76\u663e\u793a\u6570\u636e\u4f20\u8f93\u7684\u901f\u7387\uff08\u6bcf\u79d2\u4f20\u8f93\u7684\u6570\u636e\u70b9\u6570\u548cKiB\u6570\uff09\uff0c\u4ee5\u53ca\u6574\u4e2a\u6d4b\u8bd5\u8fc7\u7a0b\u6240\u9700\u7684\u65f6\u95f4\u3002\n\n#### \u7ed3\u679c\u8f93\u51fa\n\n\u7a0b\u5e8f\u7684\u8f93\u51fa\u63d0\u4f9b\u4e86\u5173\u4e8eModbus\u64cd\u4f5c\u6027\u80fd\u7684\u8be6\u7ec6\u4fe1\u606f\uff0c\u5305\u62ec\u64cd\u4f5c\u7684\u6301\u7eed\u65f6\u95f4\u3001\u603b\u5b57\u8282\u6570\u4ee5\u53ca\u8ba1\u7b97\u51fa\u7684\u6570\u636e\u4f20\u8f93\u901f\u7387\u3002\u8fd9\u4e9b\u6570\u636e\u6709\u52a9\u4e8e\u7528\u6237\u4e86\u89e3\u5728\u7279\u5b9a\u786c\u4ef6\u548c\u7f51\u7edc\u8bbe\u7f6e\u4e2d\u6267\u884cModbus\u64cd\u4f5c\u7684\u6548\u7387\u3002\n\n\u6b64\u5916\uff0c\u7a0b\u5e8f\u8fd8\u4f1a\u8ba1\u7b97\u5305\u62ecModbus TCP\u534f\u8bae\u5f00\u9500\u5728\u5185\u7684\u603b\u5b57\u8282\u6570\uff0c\u8fd9\u5bf9\u4e8e\u8bc4\u4f30\u7f51\u7edc\u8d1f\u8f7d\u548c\u4f18\u5316\u7f51\u7edc\u6027\u80fd\u7279\u522b\u91cd\u8981\u3002\n\n#### \u4f7f\u7528\u573a\u666f\u548c\u4ef7\u503c\n\n\u6b64\u6027\u80fd\u6d4b\u91cf\u5de5\u5177\u5bf9\u4e8e\u6b63\u5728\u5f00\u53d1\u6216\u90e8\u7f72\u57fa\u4e8eModbus\u7684\u7cfb\u7edf\u7684\u5de5\u7a0b\u5e08\u6781\u5177\u4ef7\u503c\u3002\u5b83\u4e0d\u4ec5\u53ef\u4ee5\u5e2e\u52a9\u4ed6\u4eec\u9a8c\u8bc1\u548c\u4f18\u5316\u7cfb\u7edf\u914d\u7f6e\uff0c\u786e\u4fdd\u5728\u751f\u4ea7\u73af\u5883\u4e2d\u8fbe\u5230\u6240\u9700\u7684\u6027\u80fd\u6807\u51c6\uff0c\u8fd8\u53ef\u4ee5\u5728\u7cfb\u7edf\u5347\u7ea7\u6216\u6269\u5c55\u524d\u8bc4\u4f30\u6f5c\u5728\u7684\u6027\u80fd\u74f6\u9888\u3002\n\n\u901a\u8fc7\u8fd9\u79cd\u65b9\u5f0f\uff0c\u5de5\u7a0b\u5e08\u53ef\u4ee5\u66f4\u6709\u6548\u5730\u7ba1\u7406Modbus\u7cfb\u7edf\u7684\u7ef4\u62a4\u548c\u5347\u7ea7\uff0c\u786e\u4fdd\u6240\u6709\u64cd\u4f5c\u90fd\u80fd\u5728\u6700\u4f18\u7684\u6027\u80fd\u6761\u4ef6\u4e0b\u8fd0\u884c\u3002\n\n---\n*modbus.cn*\n"