diff --git a/api/src/opentrons/hardware_control/simulator_setup.py b/api/src/opentrons/hardware_control/simulator_setup.py
index 9cea61839d8..f9cedf928f3 100644
--- a/api/src/opentrons/hardware_control/simulator_setup.py
+++ b/api/src/opentrons/hardware_control/simulator_setup.py
@@ -17,6 +17,7 @@
 @dataclass(frozen=True)
 class ModuleCall:
     function_name: str
+    serial_number: str
     args: List[Any] = field(default_factory=list)
     kwargs: Dict[str, Any] = field(default_factory=dict)
 
@@ -24,7 +25,6 @@ class ModuleCall:
 # Name and kwargs for a module function
 @dataclass(frozen=True)
 class ModuleItem:
-    serial_number: str
     items: List[ModuleCall] = field(default_factory=list)
 
 
@@ -205,14 +205,18 @@ def _prepare_for_ot3_simulator_setup(key: str, value: Dict[str, Any]) -> Any:
     if key == "config" and value:
         return robot_configs.build_config_ot3(value)
     if key == "attached_modules" and value:
+        attached_modules: Dict[str, ModuleItem] = {}
         # list of items with id, item - loop and set to ModuleCall
         for key, item in value.items():
-            # print(list(item['items']))
             for obj in item:
                 for data in obj["items"]:
-                    print(ModuleCall(**data))
+                    attached_modules.setdefault(key, ModuleItem().items).append(
+                        ModuleCall(**data)
+                    )
+
+        print(attached_modules)
+        print("----")
 
         # items = {k: [ModuleCall(**data) for data in v] for (k, v) in value.items()}
-        # print(items)
-        return {k: [ModuleCall(**data) for data in v] for (k, v) in value.items()}
+        return attached_modules
     return value
diff --git a/api/tests/opentrons/hardware_control/test_simulator_setup.py b/api/tests/opentrons/hardware_control/test_simulator_setup.py
index 44bda189d81..34903f0201d 100644
--- a/api/tests/opentrons/hardware_control/test_simulator_setup.py
+++ b/api/tests/opentrons/hardware_control/test_simulator_setup.py
@@ -164,30 +164,27 @@ def test_persistence_ot3(tmpdir: str) -> None:
         attached_modules={
             "magdeck": [
                 simulator_setup.ModuleItem(
-                    id="mag-123",
-                    items=[simulator_setup.ModuleCall("engage", kwargs={"height": 3})],
-                )
-            ],
-            "tempdeck": [
-                simulator_setup.ModuleItem(
-                    id="temp-123",
                     items=[
                         simulator_setup.ModuleCall(
-                            "set_temperature", kwargs={"celsius": 23}
-                        ),
-                        simulator_setup.ModuleCall(
-                            "set_temperature", kwargs={"celsius": 24}
-                        ),
+                            function_name="engage",
+                            serial_number="mag-1",
+                            kwargs={"height": 3},
+                        )
                     ],
-                ),
+                )
+            ],
+            "tempdeck": [
                 simulator_setup.ModuleItem(
-                    id="temp-1234",
                     items=[
                         simulator_setup.ModuleCall(
-                            "set_temperature", kwargs={"celsius": 23}
+                            function_name="set_temperature",
+                            serial_number="temp-1",
+                            kwargs={"celsius": 23},
                         ),
                         simulator_setup.ModuleCall(
-                            "set_temperature", kwargs={"celsius": 24}
+                            function_name="set_temperature",
+                            serial_number="temp-2",
+                            kwargs={"celsius": 24},
                         ),
                     ],
                 ),
@@ -199,4 +196,7 @@ def test_persistence_ot3(tmpdir: str) -> None:
     simulator_setup.save_simulator_setup(sim, file)
     test_sim = simulator_setup.load_simulator_setup(file)
 
+    print(sim.attached_modules)
+    print("====")
+    print(test_sim.attached_modules)
     assert test_sim == sim