allow to configure category of parameters

by default, in datafile headers only value, status etc. is stored.
put the sec node devices 'param_category' to 'general' will
put all parameters into the header

devices.py

@@ -219,6 +219,9 @@ class FrappyNode(SecNodeDevice, Moveable):
     }
     parameters = {
         'service': Param('frappy service name (main, stick or addons)', type=str, default=''),
+        'param_category': Param("category of parameters\n\n"
+                                "set to 'general' if all parameters should appear in the datafile header",
+                                type=str, default='', settable=True),
     }
 
     _service_manager = FrappyManager()
@@ -237,6 +240,17 @@ class FrappyNode(SecNodeDevice, Moveable):
             self._cfgvalue = self._cache.get(self, 'value')
         return self._cfgvalue
 
+    def createDevices(self):
+        super().createDevices()
+        if self.param_category:
+            for devname, (_, devcfg) in self.setup_info.items():
+                params_cfg = devcfg['params_cfg']
+                dev = session.devices[devname]
+                for pname, pargs in params_cfg.items():
+                    pinfo = dev.parameters[pname]
+                    if not pinfo.category:
+                        pinfo.category = self.param_category
+
     @classmethod
     def config_dirs(cls, ins, service):
         sm = cls._service_manager