fix

ophyd/signal.py

@@ -749,12 +749,13 @@ def derived_from(self):
 
     def describe(self):
         """Description based on the original signal description"""
-        desc = super().describe()[self.name]  # Description of this signal
-        desc["derived_from"] = self._derived_from.name
+        desc = super().describe()
         # Description of the derived signal
         derived_desc = self._derived_from.describe()[self._derived_from.name]
-        derived_desc.update(desc)
-        return {self.name: derived_desc}
+        # Update this signal description
+        desc[self.name].update(derived_desc)
+        desc[self.name]["derived_from"] = self._derived_from.name
+        return desc
 
     def _update_metadata_from_callback(self, **kwargs):
         updated_md = {key: kwargs[key] for key in self.metadata_keys if key in kwargs}
@@ -1573,7 +1574,8 @@ def describe(self):
         dict
             Dictionary of name and formatted description string
         """
-        desc = super().describe()[self.name]
+        ret = super().describe()
+        desc = ret[self.name]
         lower_ctrl_limit, upper_ctrl_limit = self.limits
         desc.update(
             dict(
@@ -1589,7 +1591,7 @@ def describe(self):
         if self.enum_strs is not None:
             desc["enum_strs"] = tuple(self.enum_strs)
 
-        return {self.name: desc}
+        return ret
 
 
 class EpicsSignalRO(EpicsSignalBase):