fix symbol info for function block properties with monitoring = call #261

Author: dgl-cw

pyads/symbol.py

@@ -162,7 +162,14 @@ def _create_symbol_from_info(self) -> None:
         info = adsGetSymbolInfo(self._plc._port, self._plc._adr, self.name)
 
         self.index_group = info.iGroup
-        self.index_offset = info.iOffs
+        if self.index_group == 0xF019:
+            # For function block properties with monitoring = call
+            # get symbol using handle instead
+            self.index_group = constants.ADSIGRP_SYM_VALBYHND
+            self.index_offset = self._plc.get_handle(self.name)
+        else:
+            self.index_offset = info.iOffs
+
         if info.comment:
             self.comment = info.comment
 
@@ -230,6 +237,8 @@ def __repr__(self) -> str:
     def __del__(self) -> None:
         """Destructor"""
         self.clear_device_notifications()
+        if self.index_group == constants.ADSIGRP_SYM_VALBYHND:
+            self._plc.release_handle(self.index_offset)
 
     def add_device_notification(
             self,