diff --git a/pymodbus/datastore/context.py b/pymodbus/datastore/context.py
index a5e311a34..b364f1051 100644
--- a/pymodbus/datastore/context.py
+++ b/pymodbus/datastore/context.py
@@ -100,10 +100,10 @@ def __init__(self, slaves=None, single=True):
         :param slaves: A dictionary of client contexts
         :param single: Set to true to treat this as a single context
         '''
-        self.single   = single
-        self.__slaves = slaves or {}
+        self.single = single
+        self._slaves = slaves or {}
         if self.single:
-            self.__slaves = {Defaults.UnitId: self.__slaves}
+            self._slaves = {Defaults.UnitId: self._slaves}
 
     def __iter__(self):
         ''' Iterater over the current collection of slave
@@ -111,7 +111,7 @@ def __iter__(self):
 
         :returns: An iterator over the slave contexts
         '''
-        return iteritems(self.__slaves)
+        return iteritems(self._slaves)
 
     def __contains__(self, slave):
         ''' Check if the given slave is in this list
@@ -119,7 +119,10 @@ def __contains__(self, slave):
         :param slave: slave The slave to check for existance
         :returns: True if the slave exists, False otherwise
         '''
-        return slave in self.__slaves
+        if self.single and self._slaves:
+            return True
+        else:
+            return slave in self._slaves
 
     def __setitem__(self, slave, context):
         ''' Used to set a new slave context
@@ -127,11 +130,13 @@ def __setitem__(self, slave, context):
         :param slave: The slave context to set
         :param context: The new context to set for this slave
         '''
-        if self.single: slave = Defaults.UnitId
+        if self.single:
+            slave = Defaults.UnitId
         if 0xf7 >= slave >= 0x00:
-            self.__slaves[slave] = context
+            self._slaves[slave] = context
         else:
-            raise NoSuchSlaveException('slave index :{} out of range'.format(slave))
+            raise NoSuchSlaveException('slave index :{} '
+                                       'out of range'.format(slave))
 
     def __delitem__(self, slave):
         ''' Wrapper used to access the slave context
@@ -139,9 +144,10 @@ def __delitem__(self, slave):
         :param slave: The slave context to remove
         '''
         if not self.single and (0xf7 >= slave >= 0x00):
-            del self.__slaves[slave]
+            del self._slaves[slave]
         else:
-            raise NoSuchSlaveException('slave index: {} out of range'.format(slave))
+            raise NoSuchSlaveException('slave index: {} '
+                                       'out of range'.format(slave))
 
     def __getitem__(self, slave):
         ''' Used to get access to a slave context
@@ -149,8 +155,10 @@ def __getitem__(self, slave):
         :param slave: The slave context to get
         :returns: The requested slave context
         '''
-        if self.single: slave = Defaults.UnitId
-        if slave in self.__slaves:
-            return self.__slaves.get(slave)
+        if self.single:
+            slave = Defaults.UnitId
+        if slave in self._slaves:
+            return self._slaves.get(slave)
         else:
-            raise NoSuchSlaveException("slave - {} does not exist, or is out of range".format(slave))
+            raise NoSuchSlaveException("slave - {} does not exist, "
+                                       "or is out of range".format(slave))
diff --git a/pymodbus/server/async.py b/pymodbus/server/async.py
index 5dfdc1f65..8d412174c 100644
--- a/pymodbus/server/async.py
+++ b/pymodbus/server/async.py
@@ -59,7 +59,7 @@ def dataReceived(self, data):
         if _logger.isEnabledFor(logging.DEBUG):
             _logger.debug(' '.join([hex(byte2int(x)) for x in data]))
         if not self.factory.control.ListenOnly:
-            unit_address = byte2int(data[0])
+            unit_address = byte2int(data[6])
             if unit_address in self.factory.store:
                 self.framer.processIncomingPacket(data, self._execute)
 
diff --git a/pymodbus/server/sync.py b/pymodbus/server/sync.py
index 7941701d6..253a18ee6 100644
--- a/pymodbus/server/sync.py
+++ b/pymodbus/server/sync.py
@@ -106,9 +106,14 @@ def handle(self):
                         unit_address = int(data[1:3], 16)
                     elif isinstance(self.framer, ModbusBinaryFramer):
                         unit_address = byte2int(data[1])
-                    else:
+                    elif isinstance(self.framer, ModbusRtuFramer):
                         unit_address = byte2int(data[0])
-
+                    elif isinstance(self.framer, ModbusSocketFramer):
+                        unit_address = byte2int(data[6])
+                    else:
+                        _logger.error("Unknown"
+                                      " framer - {}".format(type(self.framer)))
+                        unit_address = -1
                     if unit_address in self.server.context:
                         self.framer.processIncomingPacket(data, self.execute)
             except Exception as msg: