diff --git a/tests/ioc_plugin.py b/tests/ioc_plugin.py
index de67ea8f2..c88902838 100644
--- a/tests/ioc_plugin.py
+++ b/tests/ioc_plugin.py
@@ -4,57 +4,68 @@ import threading
 import pytest
 from morbidissimo import MorIOC
 
-# Environment variable to share the PV prefix with tests
 PREFIX_ENV = "TEST_PV_PREFIX"
 DEFAULT_PREFIX = "TEST:"
 
+# Motors you reference in tests: M1..M13
+MOTOR_IDS = [f"M{i}" for i in range(1, 14)]
+
 @pytest.fixture(scope="session", autouse=True)
 def ioc_session():
     """
-    Start exactly ONE IOC for the entire pytest session.
-    All tests can reuse it to avoid port/prefix conflicts.
-    Add all PVs needed by your test suite here.
+    Start exactly ONE IOC for the whole test session.
+    Hosts both legacy PVs (TEST:VAL, TEST:PV1..PV6) and SIM PVs
+    (TEST:SIM:VAL, TEST:SIM:M*.VAL) used by the motor tests.
     """
     prefix = os.environ.get(PREFIX_ENV, DEFAULT_PREFIX)
-    # Ensure tests can read the chosen prefix
     os.environ.setdefault(PREFIX_ENV, prefix)
 
     stop = threading.Event()
 
     def run():
         with MorIOC(prefix) as mor:
-            # Host PVs once for the whole session
+            # ---- Host PVs once
+            # Legacy/top-level PVs used by other tests
             mor.host(
-                VAL=float,                 # writable PV used in progress-bar tests
+                VAL=float,                  # TEST:VAL
                 PV1=float, PV2=float, PV3=float,
-                PV4=float, PV5=float, PV6=float,  # static PVs
+                PV4=float, PV5=float, PV6=float,
+            )
+            # SIM namespace PVs
+            mor.host(
+                **{"SIM:VAL": float},       # TEST:SIM:VAL
+                **{f"SIM:{mid}.VAL": float for mid in MOTOR_IDS},  # TEST:SIM:M*.VAL
             )
 
-            current_val = 0.0  # backing state for VAL
+            # ---- Backing state (writable PVs keep last written value)
+            state = {
+                "VAL": 0.0,
+                "SIM:VAL": 0.0,
+                **{f"SIM:{mid}.VAL": 0.0 for mid in MOTOR_IDS},
+            }
 
-            # Serve loop; keep running until the session ends
+            # ---- Serve loop
             while not stop.is_set():
-                # Make VAL writable: read incoming value and persist it
-                new_val = mor.get("VAL")
-                if new_val is not None:
-                    current_val = new_val
+                # Accept writes
+                for name in state.keys():
+                    new_val = mor.get(name)
+                    if new_val is not None:
+                        state[name] = new_val
 
-                # Serve current values (static PVs as constants)
+                # Publish current values; PV1..PV6 are static constants
                 mor.serve(
-                    VAL=current_val,
+                    **state,
                     PV1=1.0, PV2=2.0, PV3=3.0,
                     PV4=4.0, PV5=5.0, PV6=6.0,
                 )
-                time.sleep(0.05)  # small delay to avoid a busy loop
+                time.sleep(0.05)  # avoid busy loop
 
-    # Start IOC in a background thread
     t = threading.Thread(target=run, daemon=True)
     t.start()
-    time.sleep(0.8)  # give Channel Access time to announce PVs
+    time.sleep(0.8)  # let CA announce PVs
 
-    yield  # <<< tests execute during this period >>>
+    yield
 
-    # Graceful teardown
     stop.set()
     t.join(timeout=2.0)
-    time.sleep(0.2)  # allow OS to release sockets
\ No newline at end of file
+    time.sleep(0.2)