fix 2 issues with starting stopping

- secnode devices were not disconnected before stopping
  leading to error messages
- target of secnodes not properly updated

devices.py

@@ -165,8 +165,8 @@ class FrappyConfig(Device):
         self._back_to_normal = None
         while not self._shutdown_event.wait(1):
             busy = session.daemon_device._controller.status >= 0
-            if busy and cnt < 10:
-                # check only every 10 sec when busy
+            if self._restarting or (busy and cnt < 10):
+                # do not check when restarting and check only every 10 sec when busy
                 cnt += 1
                 continue
             if not busy and self._back_to_normal:
@@ -308,7 +308,6 @@ class FrappyConfig(Device):
                         used_cfg[cfg] = service
 
             for service, cfginfo in reversed(list(new_cfg.items())):
-                if cfginfo != all_cfg.get(service, ''):
                 secnode = secnodes[service]
                 if secnode:
                     secnode('')  # stop previous frappy server
@@ -735,7 +734,6 @@ class FrappyNode(SecNodeDevice, Moveable):
         self.__log_recording = ()
 
     def nodeStateChange(self, online, state):
-        # self.log.info('NODE %r %r', online, state)
         if online:
             super().nodeStateChange(online, state)
             if self._cfgvalue is None:
@@ -759,7 +757,7 @@ class FrappyNode(SecNodeDevice, Moveable):
         if not running_cfg or running_cfg == self.target:
             super().descriptiveDataChange(module, description)
         else:
-            self._disconnect(True)
+            self._disconnect(keeptarget=True)
             self._cfgvalue = running_cfg
             self._set_status(status.ERROR, 'cfg changed')
 
@@ -791,7 +789,7 @@ class FrappyNode(SecNodeDevice, Moveable):
         if cfg != running_cfg:
             self.disable()
         if running_cfg:
-            self._disconnect()
+            self._disconnect(keeptarget=not cfg)
             session.log.info('stop frappy_%s %r %r', self.service, running_cfg, cfg)
             fm.do_stop(ins, self.service)
         self._setROParam('target', cfg)
@@ -815,12 +813,12 @@ class FrappyNode(SecNodeDevice, Moveable):
             else:
                 uri = cfg
             if uri != self.uri:
-                self.uri = ''  # disconnect
+                self._disconnect(keeptarget=True)
             if uri:
                 if is_cfg:
                     session.log.info('start frappy_%s', self.service)
                     fm.do_start(ins, self.service, cfg, logger=self.log)
-                self.uri = uri  # connect
+            self.uri = uri  # connect (or disconnect)
             self._cfgvalue = cfg
             if self._cache:
                 self._cache.put(self, 'value', cfg)