diff --git a/frappy/config.py b/frappy/config.py
index f157fcc..85586c1 100644
--- a/frappy/config.py
+++ b/frappy/config.py
@@ -56,10 +56,12 @@ class Param(dict):
             kwds['value'] = value
         super().__init__(**kwds)
 
+
 class Group(tuple):
     def __new__(cls, *args):
         return super().__new__(cls, args)
 
+
 class Mod(dict):
     def __init__(self, name, cls, description, **kwds):
         super().__init__(
@@ -70,7 +72,8 @@ class Mod(dict):
 
         # matches name from spec
         if not re.match(r'^[a-zA-Z]\w{0,62}$', name, re.ASCII):
-            raise ConfigError(f'Not a valid SECoP Module name: "{name}". Does it only contain letters, numbers and underscores?')
+            raise ConfigError(f'Not a valid SECoP Module name: "{name}".'
+                              ' Does it only contain letters, numbers and underscores?')
         # Make parameters out of all keywords
         groups = {}
         for key, val in kwds.items():
@@ -85,6 +88,7 @@ class Mod(dict):
             for member in members:
                 self[member]['group'] = group
 
+
 class Collector:
     def __init__(self, cls):
         self.list = []
@@ -120,12 +124,14 @@ class Config(dict):
     def merge_modules(self, other):
         """ merges only the modules from 'other' into 'self'"""
         self.ambiguous |= self.module_names & other.module_names
+        equipment_id = other['node']['equipment_id']
         for name, mod in other.items():
             if name == 'node':
                 continue
             if name not in self.module_names:
                 self.module_names.add(name)
                 self[name] = mod
+                mod['original_id'] = equipment_id
 
 
 def process_file(filename, log):
diff --git a/frappy/modulebase.py b/frappy/modulebase.py
index d572dcd..b0154be 100644
--- a/frappy/modulebase.py
+++ b/frappy/modulebase.py
@@ -319,6 +319,8 @@ class Module(HasAccessibles):
     slowinterval = Property('poll interval for other parameters', FloatRange(0.1, 120), default=15)
     omit_unchanged_within = Property('default for minimum time between updates of unchanged values',
                                      NoneOr(FloatRange(0)), export=False, default=None)
+    original_id = Property('original equipment_id\n\ngiven only if different from equipment_id of node',
+                           NoneOr(StringType()), default=None, export=True)  # exported as custom property _original_id
     enablePoll = True
 
     pollInfo = None
diff --git a/frappy/protocol/router.py b/frappy/protocol/router.py
index 40f99f3..55d20ea 100644
--- a/frappy/protocol/router.py
+++ b/frappy/protocol/router.py
@@ -77,26 +77,30 @@ class SecopClient(frappy.client.SecopClient):
 
 
 class Router(frappy.protocol.dispatcher.Dispatcher):
-    singlenode = None
-
     def __init__(self, name, logger, options, srv):
         """initialize router
 
         Use the option node = <uri> for a single node or
         nodes = ["<uri1>", "<uri2>" ...] for multiple nodes.
-        If a single node is given, the node properties are forwarded transparently,
+        If a single node is given, and no more additional modules are given,
+        the node properties are forwarded transparently,
         else the description property is a merge from all client node properties.
         """
         uri = options.pop('node', None)
         uris = options.pop('nodes', None)
-        if uri and uris:
-            raise frappy.errors.ConfigError('can not specify node _and_ nodes')
+        try:
+            if uris is not None:
+                if isinstance(uris, str) or not all(isinstance(v, str) for v in uris) or uri:
+                    raise TypeError()
+            elif isinstance(uri, str):
+                uris = [uri]
+            else:
+                raise TypeError()
+        except Exception as e:
+            raise frappy.errors.ConfigError("a router needs either 'node' as a string'"
+                                            "' or 'nodes' as a list of strings") from e
         super().__init__(name, logger, options, srv)
-        if uri:
-            self.nodes = [SecopClient(uri, logger.getChild('routed'), self)]
-            self.singlenode = self.nodes[0]
-        else:
-            self.nodes = [SecopClient(uri, logger.getChild(f'routed{i}'), self) for i, uri in enumerate(uris)]
+        self.nodes = [SecopClient(uri, logger.getChild(f'routed{i}'), self) for i, uri in enumerate(uris)]
         # register callbacks
         for node in self.nodes:
             node.register_callback(None, node.updateEvent, node.descriptiveDataChange, node.nodeStateChange)
@@ -127,8 +131,8 @@ class Router(frappy.protocol.dispatcher.Dispatcher):
                 logger.warning('can not connect to node %r', node.nodename)
 
     def handle_describe(self, conn, specifier, data):
-        if self.singlenode:
-            return DESCRIPTIONREPLY, specifier, self.singlenode.descriptive_data
+        if len(self.nodes) == 1 and not self.secnode.modules:
+            return DESCRIPTIONREPLY, specifier, self.nodes[0].descriptive_data
         reply = super().handle_describe(conn, specifier, data)
         result = reply[2]
         allmodules = result.get('modules', {})
@@ -144,6 +148,7 @@ class Router(frappy.protocol.dispatcher.Dispatcher):
                     self.log.info('module %r is already present', modname)
                 else:
                     allmodules[modname] = moddesc
+                    moddesc.setdefault('original_id', equipment_id)
         result['modules'] = allmodules
         result['description'] = '\n\n'.join(node_description)
         return DESCRIPTIONREPLY, specifier, result
diff --git a/test/test_modules.py b/test/test_modules.py
index 9b865cd..b9069ba 100644
--- a/test/test_modules.py
+++ b/test/test_modules.py
@@ -243,7 +243,7 @@ def test_ModuleMagic():
         'export', 'group', 'description', 'features',
         'meaning', 'visibility', 'implementation', 'interface_classes', 'target', 'stop',
         'status', 'param1', 'param2', 'cmd', 'a2', 'pollinterval', 'slowinterval', 'b2',
-        'cmd2', 'value', 'a1', 'omit_unchanged_within'}
+        'cmd2', 'value', 'a1', 'omit_unchanged_within', 'original_id'}
     assert set(cfg['value'].keys()) == {
         'group', 'export', 'relative_resolution',
         'visibility', 'unit', 'default', 'value', 'datatype', 'fmtstr',