"# \u57fa\u4e8eC\u8bed\u8a00\u5d4c\u5165\u5f0f\u7cfb\u7edf\u5b9e\u73b0modbus TCP\u901a\u4fe1\u7684\u793a\u4f8b\u4ee3\u7801\n\n> 2023-02-13 | 2023-02-13\n> https:\/\/www.modbus.cn\/en\/11784.html\n\n**Modbus\u7f16\u7a0b\u5f00\u53d1**\n\n---\n\n```\n#include <stdio.h>\n#include <stdlib.h>\n#include <string.h>\n#include <errno.h>\n#include <unistd.h>\n#include <fcntl.h>\n#include <termios.h>\n#include <sys\/socket.h>\n#include <netinet\/in.h>\n#include <arpa\/inet.h>\n\n#define PORT 502\n\n#define SERVER_IP \"192.168.0.100\"\n#define DEVICE_ID 1\n\n#define BUFFER_SIZE 1024\n\nint main() {\n    \/\/ \u521b\u5efaTCP\u8fde\u63a5\n    int sockfd;\n    struct sockaddr_in server_addr;\n\n    sockfd = socket(AF_INET, SOCK_STREAM, 0);\n    if (sockfd == -1) {\n        printf(\"Failed to create socket: %s\\n\", strerror(errno));\n        return 1;\n    }\n\n    server_addr.sin_family = AF_INET;\n    server_addr.sin_port = htons(PORT);\n    server_addr.sin_addr.s_addr = inet_addr(SERVER_IP);\n\n    if (connect(sockfd, (struct sockaddr *)&server_addr, sizeof(server_addr)) == -1) {\n        printf(\"Failed to connect to server: %s\\n\", strerror(errno));\n        close(sockfd);\n        return 1;\n    }\n\n    printf(\"Connected to server successfully.\\n\");\n\n    \/\/ \u51c6\u5907modbus\u8bf7\u6c42\n    unsigned char request[BUFFER_SIZE];\n    unsigned char response[BUFFER_SIZE];\n    int request_length, response_length;\n\n    \/\/ \u8bfb\u4fdd\u6301\u5bc4\u5b58\u5668\n    int register_address = 0;\n    int register_count = 4;\n    request_length = modbus_build_request(request, DEVICE_ID, MODBUS_FC_READ_HOLDING_REGISTERS, register_address, register_count);\n\n    \/\/ \u53d1\u9001modbus\u8bf7\u6c42\n    if (send(sockfd, request, request_length, 0) == -1) {\n        printf(\"Failed to send request: %s\\n\", strerror(errno));\n        close(sockfd);\n        return 1;\n    }\n\n    printf(\"Sent request successfully.\\n\");\n\n    \/\/ \u63a5\u6536modbus\u54cd\u5e94\n    response_length = recv(sockfd, response, BUFFER_SIZE, 0);\n    if (response_length == -1) {\n        printf(\"Failed to receive response: %s\\n\", strerror(errno));\n        close(sockfd);\n        return 1;\n    }\n\n    printf(\"Received response successfully.\\n\");\n\n    \/\/ \u89e3\u6790modbus\u54cd\u5e94\n    int register_value = modbus_get_response_value(response, response_length);\n\n    printf(\"Register value: %d\\n\", register_value);\n\n    \/\/ \u5173\u95edTCP\u8fde\u63a5\n    close(sockfd);\n\n    return 0;\n}\n\n```\n\n\u4e0a\u8ff0\u793a\u4f8b\u4ee3\u7801\u4f7f\u7528\u4e86modbus\u534f\u8bae\u4e2d\u7684\u8bfb\u4fdd\u6301\u5bc4\u5b58\u5668\u529f\u80fd\uff0c\u901a\u8fc7TCP\u8fde\u63a5\u53d1\u9001\u8bf7\u6c42\uff0c\u63a5\u6536\u54cd\u5e94\u5e76\u89e3\u6790\u54cd\u5e94\uff0c\u6700\u540e\u5173\u95edTCP\u8fde\u63a5\u3002\u60a8\u53ef\u4ee5\u6839\u636e\u5b9e\u9645\u60c5\u51b5\u4fee\u6539\u4ee3\u7801\u4e2d\u7684SERVER_IP\u548cDEVICE_ID\u7b49\u53c2\u6570\uff0c\u4ee5\u53ca\u8bfb\u53d6\u7684\u4fdd\u6301\u5bc4\u5b58\u5668\u5730\u5740\u548c\u6570\u91cf\u3002\n\n```\n#include <stdio.h>\n#include <stdlib.h>\n#include <string.h>\n#include <errno.h>\n#include <unistd.h>\n#include <fcntl.h>\n#include <termios.h>\n#include <sys\/socket.h>\n#include <netinet\/in.h>\n#include <arpa\/inet.h>\n\n#define PORT 502\n\n#define SERVER_IP \"192.168.0.100\"\n#define DEVICE_ID 1\n\n#define BUFFER_SIZE 1024\n\nint main() {\n    \/\/ \u521b\u5efaTCP\u8fde\u63a5\n    int sockfd;\n    struct sockaddr_in server_addr;\n\n    sockfd = socket(AF_INET, SOCK_STREAM, 0);\n    if (sockfd == -1) {\n        printf(\"Failed to create socket: %s\\n\", strerror(errno));\n        return 1;\n    }\n\n    server_addr.sin_family = AF_INET;\n    server_addr.sin_port = htons(PORT);\n    server_addr.sin_addr.s_addr = inet_addr(SERVER_IP);\n\n    if (connect(sockfd, (struct sockaddr *)&server_addr, sizeof(server_addr)) == -1) {\n        printf(\"Failed to connect to server: %s\\n\", strerror(errno));\n        close(sockfd);\n        return 1;\n    }\n\n    printf(\"Connected to server successfully.\\n\");\n\n    \/\/ \u51c6\u5907modbus\u8bf7\u6c42\n    unsigned char request[BUFFER_SIZE];\n    unsigned char response[BUFFER_SIZE];\n    int request_length, response_length;\n\n    \/\/ \u8bfb\u4fdd\u6301\u5bc4\u5b58\u5668\n    int register_address = 0;\n    int register_count = 4;\n    request_length = modbus_build_request(request, DEVICE_ID, MODBUS_FC_READ_HOLDING_REGISTERS, register_address, register_count);\n\n    \/\/ \u53d1\u9001modbus\u8bf7\u6c42\n    if (send(sockfd, request, request_length, 0) == -1) {\n        printf(\"Failed to send request: %s\\n\", strerror(errno));\n        close(sockfd);\n        return 1;\n    }\n\n    printf(\"Sent request successfully.\\n\");\n\n    \/\/ \u63a5\u6536modbus\u54cd\u5e94\n    response_length = recv(sockfd, response, BUFFER_SIZE, 0);\n    if (response_length == -1) {\n        printf(\"Failed to receive response: %s\\n\", strerror(errno));\n        close(sockfd);\n        return 1;\n    }\n\n    printf(\"Received response successfully.\\n\");\n\n    \/\/ \u89e3\u6790modbus\u54cd\u5e94\n    int register_value = modbus_get_response_value(response, response_length);\n\n    printf(\"Register value: %d\\n\", register_value);\n\n    \/\/ \u5173\u95edTCP\u8fde\u63a5\n    close(sockfd);\n\n    return 0;\n}\n\n```\n\n---\n*modbus.cn*\n"