63 lines
1.9 KiB
Python
63 lines
1.9 KiB
Python
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import socket
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import struct
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import time
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# 配置信息
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SERVER_IP = '127.0.0.1' # 模拟本地回路
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PORT = 502
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UNIT_ID = 1
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REG_ADDR = 30 # 逻辑 40031
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def poll_register():
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# 1. 构造 Modbus TCP 请求 (Function Code 03)
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tid = 0x0001
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pid = 0x0000
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length = 6 # 后续字节长度 (UnitID 1 + PDU 5)
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uid = UNIT_ID
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fc = 0x03
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addr = REG_ADDR
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qty = 1
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# [MBAP Header] + [PDU]
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request = struct.pack('>HHHB', tid, pid, length, uid) + \
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struct.pack('>BHH', fc, addr, qty)
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try:
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with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
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s.settimeout(2.0)
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s.connect((SERVER_IP, PORT))
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print(f"[TX] 发送请求: {request.hex(' ')}")
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s.sendall(request)
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# 2. 接收响应
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response = s.recv(1024)
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if not response:
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print("[!] 服务器关闭了连接")
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return
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print(f"[RX] 收到响应: {response.hex(' ')}")
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if len(response) >= 9: # MBAP(7) + FC(1) + ByteCount(1)
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# 解析响应
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header = response[:7]
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pdu = response[7:]
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res_tid, res_pid, res_len, res_uid = struct.unpack('>HHHB', header)
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res_fc = pdu[0]
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byte_count = pdu[1]
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reg_value = struct.unpack('>H', pdu[2:4])[0]
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print(f"[+] 解析成功!")
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print(f" - 事务ID: {res_tid}")
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print(f" - 寄存器 {REG_ADDR} 的值: {hex(reg_value)} ({reg_value})")
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else:
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print("[!] 响应长度不足")
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except Exception as e:
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print(f"[!] 连接错误: {e}")
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if __name__ == "__main__":
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print("[*] Python Modbus TCP 客户端模拟启动...")
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poll_register()
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