Made some attributes of the CCan class protected to be used in any inherited class.

src/can/can.h

@@ -37,13 +37,13 @@ class CCAN : protected CComm
     std::string frame_error_event_id;// public event
     std::string data_requested_event_id;// public event
     std::string finish_can_thread_event_id;// private event
-    // internal received frame buffer
-    std::queue<struct can_frame> rx_frames;
     // reception can_id filters
     struct can_filter *rx_filters;
     int num_filters;
-    CMutex can_access;
   protected:
+    // internal received frame buffer
+    std::queue<struct can_frame> rx_frames;
+    CMutex can_access;
      /**
       * \brief Function to actually open the device
       *