diff -r 0b6ab74f4b89 -r b0d6819119c3 PLCControler.py
--- a/PLCControler.py	Wed Jun 29 12:29:14 2011 +0200
+++ b/PLCControler.py	Mon Jul 04 15:24:44 2011 +0200
@@ -1073,8 +1073,16 @@
             blocktype = self.GetBlockType(typename, debug = debug)
             if blocktype is not None:
                 tree = []
+                en = False
+                eno = False
                 for var_name, var_type, var_modifier in blocktype["inputs"] + blocktype["outputs"]:
+                    en |= var_name.upper() == "EN"
+                    eno |= var_name.upper() == "ENO"    
                     tree.append((var_name, var_type, self.GenerateVarTree(var_type, debug)))
+                if not eno:
+                    tree.insert(0, ("ENO", "BOOL", ([], [])))
+                if not en:
+                    tree.insert(0, ("EN", "BOOL", ([], [])))
                 return tree, []
             datatype = project.getdataType(typename)
             if datatype is not None: