diff --git a/ophyd_devices/sim/sim_waveform.py b/ophyd_devices/sim/sim_waveform.py
index ea4af98..f4b1cc2 100644
--- a/ophyd_devices/sim/sim_waveform.py
+++ b/ophyd_devices/sim/sim_waveform.py
@@ -4,6 +4,7 @@ import os
 import threading
 import time
 import traceback
+from typing import Any
 
 import numpy as np
 from bec_lib import messages
@@ -64,6 +65,8 @@ class SimWaveform(Device):
     )
     # Can be extend or append
     async_update = Cpt(SetableSignal, value="append", kind=Kind.config)
+    slice_size = Cpt(SetableSignal, value=100, dtype=np.int32, kind=Kind.config)
+    slice_update = Cpt(SetableSignal, value=False, dtype=bool, kind=Kind.config)
 
     def __init__(
         self,
@@ -94,6 +97,7 @@ class SimWaveform(Device):
         self.scan_info = scan_info
         if self.sim_init:
             self.sim.set_init(self.sim_init)
+        self._slice_index = 0
 
     @property
     def registered_proxies(self) -> None:
@@ -113,8 +117,23 @@ class SimWaveform(Device):
         def acquire(status: DeviceStatus):
             try:
                 for _ in range(self.burst.get()):
-                    self._run_subs(sub_type=self.SUB_MONITOR, value=self.waveform.get())
-                    self._send_async_update()
+                    values = self.waveform.get()
+                    if self.slice_update.get():
+                        size = self.slice_size.get()
+                        mod = len(values) % size
+                        num_slices = len(values) // size + int(mod > 0)
+                        for i in range(num_slices):
+                            value_slice = values[i * size : min((i + 1) * size, len(values))]
+                            logger.info(
+                                f"Sending slice {i} of {self._slice_index} with length {len(value_slice)}"
+                            )
+                            self._run_subs(sub_type=self.SUB_MONITOR, value=value_slice)
+                            self._send_async_update(index=self._slice_index, value=value_slice)
+                        self._slice_index += 1
+                    else:
+                        value = self.waveform.get()
+                        self._run_subs(sub_type=self.SUB_MONITOR, value=value)
+                        self._send_async_update(value=value)
                     if self.stopped:
                         raise DeviceStopError(f"{self.name} was stopped")
                 status.set_finished()
@@ -128,7 +147,7 @@ class SimWaveform(Device):
         self._trigger_thread.start()
         return status
 
-    def _send_async_update(self):
+    def _send_async_update(self, index: int | None = None, value: Any = None) -> None:
         """Send the async update to BEC."""
         async_update_type = self.async_update.get()
         if async_update_type not in ["extend", "append"]:
@@ -136,12 +155,21 @@ class SimWaveform(Device):
 
         waveform_shape = self.waveform_shape.get()
         if async_update_type == "append":
-            metadata = {"async_update": {"type": "add", "max_shape": [None, waveform_shape]}}
+            if index is not None:
+                metadata = {
+                    "async_update": {
+                        "type": "add_slice",
+                        "index": index,
+                        "max_shape": [None, waveform_shape],
+                    }
+                }
+            else:
+                metadata = {"async_update": {"type": "add", "max_shape": [None, waveform_shape]}}
         else:
             metadata = {"async_update": {"type": "add", "max_shape": [None]}}
 
         msg = messages.DeviceMessage(
-            signals={self.waveform.name: {"value": self.waveform.get(), "timestamp": time.time()}},
+            signals={self.waveform.name: {"value": value, "timestamp": time.time()}},
             metadata=metadata,
         )
         # logger.warning(f"Adding async update to {self.name} and {self.scan_info.msg.scan_id}")
@@ -177,6 +205,7 @@ class SimWaveform(Device):
         self.exp_time.set(self.scan_info.msg.scan_parameters["exp_time"])
         self.burst.set(self.scan_info.msg.scan_parameters["frames_per_trigger"])
         self.stopped = False
+        self._slice_index = 0
         logger.warning(f"Staged {self.name}, scan_id : {self.scan_info.msg.scan_id}")
         return super().stage()
 
@@ -186,6 +215,7 @@ class SimWaveform(Device):
         Send reads from all config signals to redis
         """
         logger.warning(f"Unstaging {self.name}, {self._staged}")
+        self._slice_index = 0
         if self.stopped is True or not self._staged:
             return super().unstage()
         return super().unstage()