"# libmodbus\u4e92\u65a5\u9501\uff08mutex\uff09\u548c\u53ef\u91cd\u5165\u9501\uff08recursive lock\uff09\u793a\u4f8b\n\n> 2023-02-12 | 2023-02-12\n> https:\/\/www.modbus.cn\/en\/11713.html\n\n**Modbus\u7f16\u7a0b\u5f00\u53d1**\n\n---\n\n- libmodbus\u5e93\u63d0\u4f9b\u4e86\u4e00\u4e9b\u9501\u673a\u5236\u4ee5\u4fdd\u62a4\u5728\u591a\u7ebf\u7a0b\u73af\u5883\u4e0b\u8bbf\u95eeModbus\u4ece\u7ad9\u8bbe\u5907\u7684\u6570\u636e\u3002\u5177\u4f53\u6765\u8bf4\uff0clibmodbus\u5e93\u63d0\u4f9b\u4e86\u4ee5\u4e0b\u4e24\u79cd\u9501\u673a\u5236\uff1a\n\n- \u4e92\u65a5\u9501\uff08mutex\uff09\uff1alibmodbus\u5e93\u4e2d\u7684modbus_t\u7ed3\u6784\u4f53\u4e2d\u5305\u542b\u4e86\u4e00\u4e2a\u4e92\u65a5\u9501\uff0c\u53ef\u4ee5\u4f7f\u7528modbus_mutex_lock\uff08\uff09\u548cmodbus_mutex_unlock\uff08\uff09\u51fd\u6570\u5bf9\u8be5\u9501\u8fdb\u884c\u52a0\u9501\u548c\u89e3\u9501\u64cd\u4f5c\uff0c\u4ee5\u4fdd\u62a4\u5728\u591a\u7ebf\u7a0b\u73af\u5883\u4e0b\u5bf9Modbus\u4ece\u7ad9\n\n- \u53ef\u91cd\u5165\u9501\uff08recursive lock\uff09\uff1alibmodbus\u5e93\u8fd8\u63d0\u4f9b\u4e86\u53ef\u91cd\u5165\u9501\u673a\u5236\uff0c\u53ef\u4ee5\u901a\u8fc7modbus_rtu_set_custom_rts\uff08\uff09\u51fd\u6570\u8bbe\u7f6e\u7528\u6237\u81ea\u5b9a\u4e49\u7684RTS\u64cd\u4f5c\u56de\u8c03\u51fd\u6570\uff0c\u5e76\u5728\u56de\u8c03\u51fd\u6570\u4e2d\u52a0\u9501\u548c\u89e3\u9501\uff0c\u4ee5\u4fdd\u62a4\u5728\u591a\u7ebf\u7a0b\u73af\u5883\u4e0b\u5bf9Modbus\u4ece\u7ad9\u8bbe\u5907\u7684\u8bbf\u95ee\u3002\n\n\u9700\u8981\u6ce8\u610f\u7684\u662f\uff0c\u4f7f\u7528\u9501\u673a\u5236\u9700\u8981\u8c28\u614e\uff0c\u56e0\u4e3a\u4e0d\u6b63\u786e\u7684\u4f7f\u7528\u4f1a\u5bfc\u81f4\u6b7b\u9501\u6216\u7ebf\u7a0b\u963b\u585e\u7b49\u95ee\u9898\uff0c\u56e0\u6b64\u5728\u591a\u7ebf\u7a0b\u73af\u5883\u4e0b\u4f7f\u7528libmodbus\u5e93\u65f6\uff0c\u9700\u8981\u4ed4\u7ec6\u8bbe\u8ba1\u548c\u5b9e\u73b0\u7ebf\u7a0b\u540c\u6b65\u673a\u5236\u3002\n\n\u4ee5\u4e0b\u662f\u4f7f\u7528libmodbus\u5e93\u7684\u4e92\u65a5\u9501\u793a\u4f8b\u4ee3\u7801\uff1a\n\n```\n#include <stdio.h>\n#include <modbus\/modbus.h>\n\nint main() {\n    modbus_t *ctx;\n    modbus_mapping_t *mapping;\n    int ret;\n\n    \/\/ \u521b\u5efaModbus\u4ece\u7ad9\u8bbe\u5907\u5e76\u5206\u914d\u6570\u636e\u5b58\u50a8\u533a\n    ctx = modbus_new_rtu(\"\/dev\/ttyS0\", 9600, 'N', 8, 1);\n    if (ctx == NULL) {\n        fprintf(stderr, \"Failed to create modbus context\\n\");\n        return -1;\n    }\n    mapping = modbus_mapping_new(0, 0, 100, 0);\n    if (mapping == NULL) {\n        fprintf(stderr, \"Failed to allocate mapping\\n\");\n        modbus_free(ctx);\n        return -1;\n    }\n\n    \/\/ \u52a0\u9501\u5e76\u8bbf\u95eeModbus\u4ece\u7ad9\u8bbe\u5907\n    modbus_mutex_lock(ctx);\n    ret = modbus_connect(ctx);\n    if (ret == -1) {\n        fprintf(stderr, \"Failed to connect to Modbus device\\n\");\n        modbus_mutex_unlock(ctx);\n        return -1;\n    }\n    ret = modbus_write_register(ctx, 0, 123);\n    if (ret == -1) {\n        fprintf(stderr, \"Failed to write register\\n\");\n        modbus_mutex_unlock(ctx);\n        return -1;\n    }\n    modbus_close(ctx);\n    modbus_mutex_unlock(ctx);\n\n    \/\/ \u91ca\u653e\u8d44\u6e90\u5e76\u9000\u51fa\n    modbus_mapping_free(mapping);\n    modbus_free(ctx);\n    return 0;\n}\n\n```\n\n\u4ee5\u4e0a\u4ee3\u7801\u4e2d\uff0c\u901a\u8fc7\u8c03\u7528modbus_mutex_lock\uff08\uff09\u51fd\u6570\u52a0\u9501\uff0c\u7136\u540e\u8bbf\u95eeModbus\u4ece\u7ad9\u8bbe\u5907\uff0c\u6700\u540e\u901a\u8fc7\u8c03\u7528modbus_mutex_unlock\uff08\uff09\u51fd\u6570\u89e3\u9501\u3002\u4f7f\u7528\u4e92\u65a5\u9501\u53ef\u4ee5\u786e\u4fdd\u5728\u591a\u7ebf\u7a0b\u73af\u5883\u4e0b\uff0c\u540c\u65f6\u53ea\u6709\u4e00\u4e2a\u7ebf\u7a0b\u80fd\u591f\u8bbf\u95eeModbus\u4ece\u7ad9\u8bbe\u5907\uff0c\u907f\u514d\u4e86\u7ade\u6001\u6761\u4ef6\u7b49\u95ee\u9898\u3002\n\n\u4ee5\u4e0b\u662f\u4f7f\u7528libmodbus\u5e93\u7684\u53ef\u91cd\u5165\u9501\u793a\u4f8b\u4ee3\u7801\uff1a\n\n```\n#include <stdio.h>\n#include <modbus\/modbus.h>\n\n\/\/ \u5b9a\u4e49\u53ef\u91cd\u5165\u9501\nmodbus_t *g_ctx = NULL;\nmodbus_mutex_t g_lock;\n\n\/\/ \u5b9a\u4e49\u7528\u6237\u81ea\u5b9a\u4e49\u7684RTS\u56de\u8c03\u51fd\u6570\nvoid custom_rts(modbus_t *ctx, int on) {\n    if (on) {\n        modbus_mutex_lock(&g_lock);\n    } else {\n        modbus_mutex_unlock(&g_lock);\n    }\n}\n\nint main() {\n    modbus_mapping_t *mapping;\n    int ret;\n\n    \/\/ \u521b\u5efaModbus\u4ece\u7ad9\u8bbe\u5907\u5e76\u5206\u914d\u6570\u636e\u5b58\u50a8\u533a\n    g_ctx = modbus_new_rtu(\"\/dev\/ttyS0\", 9600, 'N', 8, 1);\n    if (g_ctx == NULL) {\n        fprintf(stderr, \"Failed to create modbus context\\n\");\n        return -1;\n    }\n    mapping = modbus_mapping_new(0, 0, 100, 0);\n    if (mapping == NULL) {\n        fprintf(stderr, \"Failed to allocate mapping\\n\");\n        modbus_free(g_ctx);\n        return -1;\n    }\n\n    \/\/ \u8bbe\u7f6e\u7528\u6237\u81ea\u5b9a\u4e49\u7684RTS\u56de\u8c03\u51fd\u6570\u5e76\u8bbf\u95eeModbus\u4ece\u7ad9\u8bbe\u5907\n    modbus_set_rts(g_ctx, custom_rts);\n    ret = modbus_write_register(g_ctx, 0, 123);\n    if (ret == -1) {\n        fprintf(stderr, \"Failed to write register\\n\");\n       \n\n```\n\n---\n*modbus.cn*\n"