diff --git a/src/controller.rs b/src/controller.rs
index 42a8c020..6585280e 100644
--- a/src/controller.rs
+++ b/src/controller.rs
@@ -113,20 +113,23 @@ impl Controller {
 
     /// Sends the specified message to the specified remote node. The function automatically updates the SEOJ (Source ECHONET-Lite object) and TID (Transaction ID) in the specified message, so you do not need to set the message fields.
     pub fn send_message(&self, remote_node: &RemoteNode, msg: &mut Message) -> bool {
-        let ctrl = self.node.lock().unwrap();
-        ctrl.send_message(remote_node, msg)
+        if self.node.try_lock().is_err() {
+            return false;
+        }
+        let node = self.node.lock().unwrap();
+        node.send_message(remote_node, msg)
     }
 
     /// Posts the specified message to the remote node and waits for the response using the messaging channel. TThe function automatically updates the SEOJ (Source ECHONET-Lite object) and TID (Transaction ID) in the specified message, so you do not need to set the message fields.
     pub fn post_message(&self, remote_node: &RemoteNode, msg: &mut Message) -> Receiver<Message> {
-        let ctrl = self.node.lock().unwrap();
-        ctrl.post_message(remote_node, msg)
+        let node = self.node.lock().unwrap();
+        node.post_message(remote_node, msg)
     }
 
     /// Starts the controller node to communicate with other ECHONET-Lite nodes on the local network.
     pub fn start(&mut self) -> bool {
-        let mut ctrl = self.node.lock().unwrap();
-        if !ctrl.start() {
+        let mut node = self.node.lock().unwrap();
+        if !node.start() {
             return false;
         }
         true
@@ -134,8 +137,8 @@ impl Controller {
 
     /// Stops the controller node, and clears all searched remote nodes.
     pub fn stop(&mut self) -> bool {
-        let mut ctrl = self.node.lock().unwrap();
-        ctrl.stop()
+        let mut node = self.node.lock().unwrap();
+        node.stop()
     }
 }