do not remove aliases with targets not inheriting frm SecopDevice

devices.py

@@ -32,7 +32,7 @@ import json
 from nicos import config, session
 from nicos.core import Override, Param, Moveable, status, POLLER, SIMULATION, DeviceAlias, \
     Device, anytype, listof, MASTER
-from nicos.devices.secop.devices import SecNodeDevice
+from nicos.devices.secop.devices import SecNodeDevice, SecopDevice, DefunctDevice
 from nicos.core.utils import createThread
 from nicos.utils.comparestrings import compare
 from nicos.devices.secop.devices import get_attaching_devices
@@ -662,9 +662,15 @@ class FrappyConfig(Device):
         if new_aliases or predef_aliases:
             for aliasname, devname in new_aliases.items():
                 if devname is None:
-                    session.destroyDevice(aliasname)
-                    session.configured_devices.pop(aliasname, None)
-                    session.dynamic_devices.pop(aliasname, None)
+                    aliasdev = session.devices.get(aliasname)
+                    if aliasdev:
+                        aliastarget = session.devices.get(aliasdev.alias)
+                        if isinstance(aliastarget, (SecopDevice, DefunctDevice)):
+                            session.destroyDevice(aliasname)
+                            session.configured_devices.pop(aliasname, None)
+                            session.dynamic_devices.pop(aliasname, None)
+                        elif aliastarget:
+                            session.log.info('frappy_setup does not remove %s', aliasname)
                 else:
                     dev = session.devices.get(devname)
                     devcfg = ('nicos.core.DeviceAlias', {})