diff --git a/script/RobotTCP.py b/script/RobotTCP.py
index ac84e97..c195072 100644
--- a/script/RobotTCP.py
+++ b/script/RobotTCP.py
@@ -194,7 +194,7 @@ class RobotTCP(TcpDevice, Stoppable):
 
     def is_empty(self):
         self.empty = self.eval_bool("isEmpty()")
-        return self.powered
+        return self.empty
 
     def is_settled(self):
         self.settled = self.eval_bool("isSettled()")