diff --git a/device/win_usb/win_usb.h b/device/win_usb/win_usb.h
index 9407da4..b5add8d 100644
--- a/device/win_usb/win_usb.h
+++ b/device/win_usb/win_usb.h
@@ -150,22 +150,25 @@ class usb_monitor	//	consider as libusb_context
 	std::vector<usb_device*>		devices_;
 	std::shared_ptr<std::thread>	handle_msg_;
 	DWORD							handle_msg_id_;
+	HWND							wnd_monitor_;
 	std::string						cur_dev_name_;
 	volatile bool					run_;
+	std::vector<std::string>		found_usb_devs_;
 
-	HWND	wnd_monitor_;
 	static LRESULT CALLBACK monitor_wnd_proc(HWND hwnd, UINT msg, WPARAM wp, LPARAM lp);
 	static void register_monitor_wnd(const wchar_t* cls);
 
 	void notify_usb_event(usb_device*& dev, bool arrive);
 	int on_usb_pnp(WPARAM wp, LPARAM lp);
 	void find_usb(std::vector<std::string>& usb_devs);
+	void find_usb_and_trigger_event(void);
 
 public:
 	usb_monitor();
 	~usb_monitor();
 
 	static usb_monitor* usb_monitor_;
+	static UINT			find_usb_timer_;	// set when RegisterDeviceNotification failed
 
 public:
 	usb_callback* reg_callback(libusb_hotplug_callback_fn cb, void* param);