注意：

❌ 问题出在哪？

%s 是解析字符串时遇到空白字符（空格、回车、换行）才结束，
而你用了 : 作为分隔符，但 %s 不会自动把冒号当成结束符！

所以这句：

sscanf("VNBR:D583:200202213205", "%s:%s:%2d...", ...)

第一个 %s 会把整串 "VNBR:D583:200202213205" 吞下去！

char RX_buf[] = "VNBR:D583:200202213205";

struct {
  char kind[5];
  char signal[5];
  int Year, Month, Day, Hour, Min, Sec;
} in_parking;

sscanf(RX_buf, "%4s:%4s:%2d%2d%2d%2d%2d%2d",
       in_parking.kind, in_parking.signal,
       &in_parking.Year, &in_parking.Month, &in_parking.Day,
       &in_parking.Hour, &in_parking.Min, &in_parking.Sec);

printf("%s:%s:%02d%02d%02d%02d%02d%02d\r\n",
       in_parking.kind, in_parking.signal,
       in_parking.Year, in_parking.Month, in_parking.Day,
       in_parking.Hour, in_parking.Min, in_parking.Sec);