diff --git a/components/actor/hendiCtrl.py b/components/actor/hendiCtrl.py
index 0fa175f..88da308 100755
--- a/components/actor/hendiCtrl.py
+++ b/components/actor/hendiCtrl.py
@@ -118,6 +118,8 @@ class HendiCtrl:
 	def cmd(self, req):
 		self.__write(req)
 		rsp = self.__read()
+		if len(rsp) == 0:
+			raise HendiException(f"Communication error")
 		if "OK" not in rsp[0]:
 			raise HendiException(f"Communication error")