diff --git a/script/local.py b/script/local.py
index 0871366..d766906 100644
--- a/script/local.py
+++ b/script/local.py
@@ -16,7 +16,7 @@ class RobotTCP(TcpDevice):
          self.trailer = "\n"
          self.msg_id = 0
 
-    def sendReceive(msg):
+    def sendReceive(self, msg):
         tx = self.header if (self.header != None) else  self.header
         id = "%03d" % self.msg_id
         self.msg_id = (self.msg_id+1)%1000