diff --git a/link_test/link_test_receive_vertex.py b/link_test/link_test_receive_vertex.py
index 5d186bd3..f8b9507d 100644
--- a/link_test/link_test_receive_vertex.py
+++ b/link_test/link_test_receive_vertex.py
@@ -132,10 +132,14 @@ def generate_machine_data_specification(
                 config[0].receive_keys[i] = 0xFFFFFFFF
                 config[0].receive_masks[i] = 0
             else:
-                info = r_info.get_routing_info_from_pre_vertex(
-                    self.__neighbours[i], PARTITION_NAME)
-                config[0].receive_keys[i] = info.key
-                config[0].receive_masks[i] = info.mask
+                if self.__write_routes:
+                    config[0].receive_keys[i] = self.__neighbours[i].base_key
+                    config[0].receive_masks[i] = self.__neighbours[i].mask
+                else:
+                    info = r_info.get_routing_info_from_pre_vertex(
+                        self.__neighbours[i], PARTITION_NAME)
+                    config[0].receive_keys[i] = info.key
+                    config[0].receive_masks[i] = info.mask
         config[0].packet_count_ok = (
             (self.__sends_per_ts - self.__drops_per_ts_allowed) *
             self.__run_time)
diff --git a/link_test/link_test_send_vertex.py b/link_test/link_test_send_vertex.py
index afd862b4..e486e24c 100644
--- a/link_test/link_test_send_vertex.py
+++ b/link_test/link_test_send_vertex.py
@@ -27,6 +27,7 @@
     MachineDataSpecableVertex)
 from spinn_front_end_common.data.fec_data_view import FecDataView
 from spinnaker_graph_front_end.utilities import SimulatorVertex
+from pacman.utilities.utility_calls import get_n_bits
 
 logger = FormatAdapter(logging.getLogger(__name__))
 
@@ -77,6 +78,11 @@ def __init__(self, x, y, sends_per_ts, write_route,
         self.__y = y
         self.__sends_per_ts = sends_per_ts
         self.__write_route = write_route
+        self.__key = None
+        self.__mask = None
+        if not self.__write_route:
+            self.__key = (self.__x << 24) | (self.__y << 16)
+            self.__mask = 0xFFFF0000
 
     @overrides(SimulatorVertex.get_fixed_location)
     def get_fixed_location(self):
@@ -95,12 +101,16 @@ def generate_machine_data_specification(
         self.generate_system_region(spec, DataRegions.SYSTEM)
 
         # Make a config
-        r_info = FecDataView.get_routing_infos()
-        ts = FecDataView.get_simulation_time_step_us()
         config = (ConfigData * 1)()
-        info = r_info.get_routing_info_from_pre_vertex(self, PARTITION_NAME)
-        config[0].key = info.key
-        config[0].mask = info.mask
+        r_info = FecDataView.get_routing_infos()
+        if self.__write_route:
+            config[0].key = self.__key
+            config[0].mask = self.__mask
+        else:
+            ts = FecDataView.get_simulation_time_step_us()
+            info = r_info.get_routing_info_from_pre_vertex(self, PARTITION_NAME)
+            config[0].key = info.key
+            config[0].mask = info.mask
         config[0].sends_per_timestep = self.__sends_per_ts
         config[0].time_between_sends_us = int((ts / 2) / self.__sends_per_ts)
         config[0].write_route = self.__write_route
@@ -116,3 +126,12 @@ def generate_machine_data_specification(
 
     def get_n_keys_for_partition(self, partition_id):
         return self.__sends_per_ts
+
+    @property
+    def base_key(self):
+        return self.__key
+
+    @property
+    def mask(self):
+        return self.__mask
+