diff --git a/artiq/gateware/rtio/sed/lane_distributor.py b/artiq/gateware/rtio/sed/lane_distributor.py
index f2524d012..d21d40484 100644
--- a/artiq/gateware/rtio/sed/lane_distributor.py
+++ b/artiq/gateware/rtio/sed/lane_distributor.py
@@ -1,19 +1,12 @@
 from migen import *
 
 from artiq.gateware.rtio import cri
+from artiq.gateware.rtio.sed import layouts
 
 
 __all__ = ["LaneDistributor"]
 
 
-def layout_lane_io(seqn_width, layout_payload):
-    return [
-        ("we", 1, DIR_M_TO_S),
-        ("writable", 1, DIR_S_TO_M),
-        ("seqn", seqn_width, DIR_M_TO_S),
-        ("payload", [(a, b, DIR_M_TO_S) for a, b in layout_payload])
-    ]
-
 
 # CRI write happens in 3 cycles:
 # 1. set timestamp
@@ -31,7 +24,7 @@ class LaneDistributor(Module):
 
         self.cri = cri.Interface()
         self.minimum_coarse_timestamp = Signal(64-fine_ts_width)
-        self.lane_io = [Record(layout_lane_io(seqn_width, layout_payload))
+        self.lane_io = [Record(layouts.fifo_ingress(seqn_width, layout_payload))
                         for _ in range(lane_count)]
 
         # # #
diff --git a/artiq/gateware/rtio/sed/layouts.py b/artiq/gateware/rtio/sed/layouts.py
new file mode 100644
index 000000000..4408a5d00
--- /dev/null
+++ b/artiq/gateware/rtio/sed/layouts.py
@@ -0,0 +1,67 @@
+from migen import *
+
+from artiq.gateware.rtio import rtlink
+
+
+def fifo_payload(channels):
+    address_width = max(rtlink.get_address_width(channel.interface)
+                        for channel in channels)
+    data_width = max(rtlink.get_data_width(channel.interface)
+                     for channel in channels)
+
+    layout = [
+        ("channel", bits_for(len(channels)-1)),
+        ("timestamp", 64)
+    ]
+    if address_width:
+        layout.append(("address", address_width))
+    if data_width:
+        layout.append(("data", data_width))
+
+    return layout
+
+
+def fifo_ingress(seqn_width, layout_payload):
+    return [
+        ("we", 1, DIR_M_TO_S),
+        ("writable", 1, DIR_S_TO_M),
+        ("seqn", seqn_width, DIR_M_TO_S),
+        ("payload", [(a, b, DIR_M_TO_S) for a, b in layout_payload])
+    ]
+
+
+def fifo_egress(seqn_width, layout_payload):
+    return [
+        ("re", 1, DIR_S_TO_M),
+        ("readable", 1, DIR_M_TO_S),
+        ("seqn", seqn_width, DIR_M_TO_S),
+        ("payload", [(a, b, DIR_M_TO_S) for a, b in layout_payload])
+    ]
+
+
+def output_network_payload(channels):
+    fine_ts_width = max(rtlink.get_fine_ts_width(channel.interface)
+                        for channel in channels)
+    address_width = max(rtlink.get_address_width(channel.interface)
+                        for channel in channels)
+    data_width = max(rtlink.get_data_width(channel.interface)
+                     for channel in channels)
+
+    layout = [("channel", bits_for(len(channels)-1))]
+    if fine_ts_width:
+        layout.append(("fine_ts", fine_ts_width))
+    if address_width:
+        layout.append(("address", address_width))
+    if data_width:
+        layout.append(("data", data_width))
+
+    return layout
+
+
+def output_network_node(seqn_width, layout_payload):
+    return [
+        ("valid", 1),
+        ("seqn", seqn_width),
+        ("replace_occured", 1),
+        ("payload", layout_payload)
+    ]
diff --git a/artiq/gateware/rtio/sed/output_driver.py b/artiq/gateware/rtio/sed/output_driver.py
index 5ee24753e..4edf83d34 100644
--- a/artiq/gateware/rtio/sed/output_driver.py
+++ b/artiq/gateware/rtio/sed/output_driver.py
@@ -3,7 +3,7 @@ from operator import or_
 
 from migen import *
 
-from artiq.gateware.rtio import rtlink
+from artiq.gateware.rtio.sed import layouts
 from artiq.gateware.rtio.sed.output_network import OutputNetwork
 
 
@@ -17,21 +17,8 @@ class OutputDriver(Module):
         self.busy = Signal()
         self.busy_channel = Signal(max=len(channels))
 
-        fine_ts_width = max(rtlink.get_fine_ts_width(channel.interface)
-                            for channel in channels)
-        address_width = max(rtlink.get_address_width(channel.interface)
-                            for channel in channels)
-        data_width = max(rtlink.get_data_width(channel.interface)
-                         for channel in channels)
-
         # output network
-        layout_on_payload = [("channel", bits_for(len(channels)-1))]
-        if fine_ts_width:
-            layout_on_payload.append(("fine_ts", fine_ts_width))
-        if address_width:
-            layout_on_payload.append(("address", address_width))
-        if data_width:
-            layout_on_payload.append(("data", data_width))
+        layout_on_payload = layouts.output_network_payload(channels)
         output_network = OutputNetwork(lane_count, seqn_width, layout_on_payload)
         self.submodules += output_network
         self.input = output_network.input
diff --git a/artiq/gateware/rtio/sed/output_network.py b/artiq/gateware/rtio/sed/output_network.py
index edb875b1c..05797bdcb 100644
--- a/artiq/gateware/rtio/sed/output_network.py
+++ b/artiq/gateware/rtio/sed/output_network.py
@@ -1,5 +1,7 @@
 from migen import *
 
+from artiq.gateware.rtio.sed import layouts
+
 
 __all__ = ["latency", "OutputNetwork"]
 
@@ -42,28 +44,19 @@ def latency(lane_count):
     return sum(l for l in range(1, d+1))
 
 
-def layout_node_data(seqn_width, layout_payload):
-    return [
-        ("valid", 1),
-        ("seqn", seqn_width),
-        ("replace_occured", 1),
-        ("payload", layout_payload)
-    ]
-
-
 def cmp_wrap(a, b):
     return Mux(a[-2:] == ~b[-2:], a[0], a[:-2] < b[:-2])
 
 
 class OutputNetwork(Module):
     def __init__(self, lane_count, seqn_width, layout_payload):
-        self.input = [Record(layout_node_data(seqn_width, layout_payload))
+        self.input = [Record(layouts.output_network_node(seqn_width, layout_payload))
                       for _ in range(lane_count)]
         self.output = None
 
         step_input = self.input
         for step in boms_steps_pairs(lane_count):
-            step_output = [Record(layout_node_data(seqn_width, layout_payload))
+            step_output = [Record(layouts.output_network_node(seqn_width, layout_payload))
                            for _ in range(lane_count)]
 
             for node1, node2 in step: