HasControlledBy: update target without switching to self control

when a HeaterOutput module is used e.g. from a software loop,
a method is needed to update the output without switching to
self-controlled

Change-Id: I9c83b4e172e14812a405e836757491622ff5f949
Reviewed-on: https://forge.frm2.tum.de/review/c/secop/frappy/+/33903
Reviewed-by: Markus Zolliker <markus.zolliker@psi.ch>
Tested-by: Jenkins Automated Tests <pedersen+jenkins@frm2.tum.de>
Reviewed-by: Enrico Faulhaber <enrico.faulhaber@frm2.tum.de>

frappy/mixins.py

@@ -56,6 +56,20 @@ class HasControlledBy:
             for deactivate_control in self.inputCallbacks.values():
                 deactivate_control(self.name)
 
+    def update_target(self, module, value):
+        """update internal target value
+
+        as write_target would switch to manual mode, the controlling module
+        has to use this method to update the value
+
+        override and super call, if other actions are needed
+        """
+        if self.controlled_by != module:
+            deactivate_control = self.inputCallbacks.get(self.controlled_by)
+            if deactivate_control:
+                deactivate_control(module)
+        self.target = value
+
 
 class HasOutputModule:
     """mixin for modules having an output module