Index: dialin/protocols/CAN.py
===================================================================
diff -u -r0188c0a21079a4c92efca69e298beeccb93ed22c -re914c6b16fd5114f4b5990d28eaa853509f62c64
--- dialin/protocols/CAN.py	(.../CAN.py)	(revision 0188c0a21079a4c92efca69e298beeccb93ed22c)
+++ dialin/protocols/CAN.py	(.../CAN.py)	(revision e914c6b16fd5114f4b5990d28eaa853509f62c64)
@@ -465,6 +465,7 @@
         """
         self.message_queue_mutex = threading.Lock()
         self.response_dictionary_mutex = threading.Lock()
+        self.transmitting_mutex = threading.Lock()
         self.logger = logger
         self.message_queue = deque()
         self.callback_listener_complete_messages = None 
@@ -646,6 +647,8 @@
 
                             # If it is not, this is a publication message and we need to call it's register function
                             else:
+                                self.response_dictionary_mutex.acquire()
+
                                 if DenaliCanMessenger.is_ui_received_channel(dialin_ch_id):  # check if the channel is in ui channels
                                     if self.ui_received_function_ptr is not None:
                                         self.thread_pool_executor.submit(
@@ -660,6 +663,7 @@
                                             self.sync_response_dictionary[dialin_ch_id][dialin_msg_id][function_id],
                                             complete_dialin_message, message.timestamp)
 
+                                self.response_dictionary_mutex.release()
                         else:
                             self.logger.critical("Invalid message: {}\n".format(self.messages))
 
@@ -754,6 +758,8 @@
             number_of_packets = DenaliMessage.get_total_packets(padded_can_message_array)
 
             # We are sending one message at a time on CAN
+            self.transmitting_mutex.acquire()
+
             for n in range(number_of_packets):
                 packet = padded_can_message_array[n * DenaliMessage.PACKET_LENGTH:
                                                   (n + 1) * DenaliMessage.PACKET_LENGTH]
@@ -765,6 +771,8 @@
 
                 self.bus.send(packet, 0)  # 0.1)
 
+            self.transmitting_mutex.release()
+
             # After all messages have been sent, we clear a flag
             self.send_event.clear()