fix: DG430 协议校验 off-by-one，payload 范围修正

src/dg430.py

@@ -65,11 +65,11 @@ def verify_packet(data: bytes) -> bool:
         return False
 
     length = data[2]
-    expected_len = 1 + 1 + 1 + length + 1 + 1  # STX + ADDR + LEN + DATA + XOR + SUM
+    expected_len = 1 + 1 + 1 + length + 1 + 1  # STX + ADDR + LEN + DATA(LEN) + XOR + SUM
     if len(data) != expected_len:
         return False
 
-    payload_end = 4 + length  # STX(1) + ADDR(1) + LEN(1) + CMD(1) + DATA(LEN-1)
+    payload_end = 3 + length  # 校验范围 [ADDR .. DATA末尾]
     actual_xor = _xor_checksum(data, 1, payload_end)
     actual_sum = _sum_checksum(data, 1, payload_end)
 
@@ -91,7 +91,7 @@ def hex_str_to_bytes(hex_str: str) -> bytes:
 def parse_b2_status(data: bytes) -> DG430Status | None:
     """解析 0xB2 状态上报包
 
-    格式: STX | ADDR | LEN(0x18=24) | 0xB2 | 20字节状态内容 | XOR | SUM
+    格式: STX | ADDR | LEN | CMD | DATA(LEN-1 bytes) | XOR | SUM
     """
     if not verify_packet(data):
         logger.warning("DG430 数据包校验失败")
@@ -103,7 +103,10 @@ def parse_b2_status(data: bytes) -> DG430Status | None:
         logger.debug(f"非 B2 指令: 0x{cmd:02X}")
         return None
 
-    payload = data[4:24]  # 20 字节状态内容
+    payload = data[4:3 + data[2]]  # DATA = LEN - 1 bytes (CMD 占位置 3)
+    if len(payload) < 20:
+        logger.warning(f"B2 数据长度不足: {len(payload)} < 20")
+        return None
 
     # 设备型号
     dev_model = payload[0]   # 1=PD132, 2=DLD110
@@ -125,9 +128,9 @@ def parse_b2_status(data: bytes) -> DG430Status | None:
     enter_dist = _le16(payload, 13)
     exit_dist = _le16(payload, 15)
 
-    # 速度 dm/s
+    # 速度 dm/s (V2.0.2 新增)
-    enter_speed = _le16(payload, 17)
+    enter_speed = _le16(payload, 17) if len(payload) >= 19 else 0
-    exit_speed = _le16(payload, 19)
+    exit_speed = _le16(payload, 19) if len(payload) >= 21 else 0
 
     return DG430Status(
         addr=addr,