diff --git a/ophyd_devices/sim/sim_signals.py b/ophyd_devices/sim/sim_signals.py
index fe9653d..9cc443d 100644
--- a/ophyd_devices/sim/sim_signals.py
+++ b/ophyd_devices/sim/sim_signals.py
@@ -4,7 +4,7 @@ import time
 
 import numpy as np
 from bec_lib import bec_logger
-from ophyd import Kind, Signal
+from ophyd import DeviceStatus, Kind, Signal
 from ophyd.utils import ReadOnlyError
 
 from ophyd_devices.utils.bec_device_base import BECDeviceBase
@@ -87,10 +87,18 @@ class SetableSignal(Signal):
 
         Core function for signal.
         """
+        self.check_value(value)
         self._update_sim_state(value)
         self._value = value
         self._run_subs(sub_type=self.SUB_VALUE, value=value)
 
+    def set(self, value):
+        """Set method"""
+        self.put(value)
+        status = DeviceStatus(self)
+        status.set_finished()
+        return status
+
     def describe(self):
         """Describe the readback signal.
 
diff --git a/ophyd_devices/sim/sim_waveform.py b/ophyd_devices/sim/sim_waveform.py
index ea4af98..3bec4cf 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
@@ -11,6 +12,7 @@ from bec_lib.endpoints import MessageEndpoints
 from bec_lib.logger import bec_logger
 from ophyd import Component as Cpt
 from ophyd import Device, DeviceStatus, Kind, Staged
+from typeguard import typechecked
 
 from ophyd_devices.sim.sim_data import SimulatedDataWaveform
 from ophyd_devices.sim.sim_signals import ReadOnlySignal, SetableSignal
@@ -20,6 +22,31 @@ from ophyd_devices.utils.errors import DeviceStopError
 logger = bec_logger.logger
 
 
+class AsyncUpdateSignal(SetableSignal):
+    """Async updated signal, with check for async_update type."""
+
+    def check_value(self, value, **kwargs) -> None:
+        """Check the value of the async_update signal."""
+        if value not in ["add_slice", "add"]:
+            raise ValueError(f"Invalid async_update type: {value} for signal {self.name}")
+
+    # FIXME: BEC issue #443 remove this method once tests in BEC are updated.
+    def put(self, value: Any) -> None:
+        """Put the value of the async_update signal."""
+        if value in ["append", "extend"]:
+            if value == "append":
+                logger.warning(
+                    f"Deprecated async_update of type {value} for signal {self.name}, falling back to 'add_slice'"
+                )
+                value = "add_slice"
+            elif value == "extend":
+                logger.warning(
+                    f"Deprecated async_update of type {value} for signal {self.name}, falling back to 'add'"
+                )
+                value = "add"
+        super().put(value)
+
+
 class SimWaveform(Device):
     """A simulated device mimic any 1D Waveform detector.
 
@@ -39,7 +66,7 @@ class SimWaveform(Device):
 
     """
 
-    USER_ACCESS = ["sim", "registered_proxies"]
+    USER_ACCESS = ["sim", "registered_proxies", "delay_slice_update"]
 
     sim_cls = SimulatedDataWaveform
     SHAPE = (1000,)
@@ -60,10 +87,11 @@ class SimWaveform(Device):
         name="waveform",
         value=np.empty(SHAPE, dtype=BIT_DEPTH),
         compute_readback=True,
-        kind=Kind.normal,
+        kind=Kind.hinted,
     )
     # Can be extend or append
-    async_update = Cpt(SetableSignal, value="append", kind=Kind.config)
+    async_update = Cpt(AsyncUpdateSignal, value="add", kind=Kind.config)
+    slice_size = Cpt(SetableSignal, value=100, dtype=np.int32, kind=Kind.config)
 
     def __init__(
         self,
@@ -92,8 +120,20 @@ class SimWaveform(Device):
         self._staged = Staged.no
         self._trigger_thread = None
         self.scan_info = scan_info
+        self._delay_slice_update = False
         if self.sim_init:
             self.sim.set_init(self.sim_init)
+        self._slice_index = 0
+
+    @property
+    def delay_slice_update(self) -> bool:
+        """Delay updates in-between slices specified by waveform_shape and slice_size."""
+        return self._delay_slice_update
+
+    @typechecked
+    @delay_slice_update.setter
+    def delay_slice_update(self, value: bool) -> None:
+        self._delay_slice_update = value
 
     @property
     def registered_proxies(self) -> None:
@@ -113,8 +153,33 @@ 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 of the Waveform
+                    values = self.waveform.get()
+                    # add_slice option
+                    if self.async_update.get() == "add_slice":
+                        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)
+                            if self.delay_slice_update is True:
+                                time.sleep(0.025)  # 25ms to be really fast
+                            if self.stopped:
+                                raise DeviceStopError(f"{self.name} was stopped")
+                        self._slice_index += 1
+                    # option add
+                    elif self.async_update.get() == "add":
+                        self._run_subs(sub_type=self.SUB_MONITOR, value=values)
+                        self._send_async_update(value=values)
+                    else:
+                        # This should never happen, but just in case
+                        # we raise an exception
+                        raise ValueError(f"Invalid async_update type: {self.async_update.get()}")
                     if self.stopped:
                         raise DeviceStopError(f"{self.name} was stopped")
                 status.set_finished()
@@ -128,23 +193,41 @@ class SimWaveform(Device):
         self._trigger_thread.start()
         return status
 
-    def _send_async_update(self):
-        """Send the async update to BEC."""
-        async_update_type = self.async_update.get()
-        if async_update_type not in ["extend", "append"]:
-            raise ValueError(f"Invalid async_update type: {async_update_type}")
+    def _send_async_update(self, value: Any, index: int | None = None) -> None:
+        """
+        Send the async update to BEC.
 
+        Args:
+            index (int | None): The index of the slice to be sent. If None, the entire waveform is sent.
+            value (Any): The value to be sent.
+        """
+        async_update_type = self.async_update.get()
         waveform_shape = self.waveform_shape.get()
-        if async_update_type == "append":
-            metadata = {"async_update": {"type": "add", "max_shape": [None, waveform_shape]}}
-        else:
+        if async_update_type == "add_slice":
+            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]}}
+        elif async_update_type == "add":
             metadata = {"async_update": {"type": "add", "max_shape": [None]}}
+        else:
+            # Again, this should never happen -> check_value,
+            # but just in case we raise an exception
+            raise ValueError(
+                f"Invalid async_update type: {async_update_type} for device {self.name}"
+            )
 
         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}")
+        # Send the message to BEC
         self.connector.xadd(
             MessageEndpoints.device_async_readback(
                 scan_id=self.scan_info.msg.scan_id, device=self.name
@@ -177,6 +260,7 @@ 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 +270,7 @@ 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()
diff --git a/tests/test_simulation.py b/tests/test_simulation.py
index beb6284..7293f8b 100644
--- a/tests/test_simulation.py
+++ b/tests/test_simulation.py
@@ -1,4 +1,4 @@
-""" This module contains tests for the simulation devices in ophyd_devices """
+"""This module contains tests for the simulation devices in ophyd_devices"""
 
 # pylint: disable: all
 import os
@@ -765,3 +765,70 @@ def test_waveform(waveform):
     assert status.done is True
     assert mock_connector.xadd.call_count == 1
     assert mock_run_subs.call_count == 1
+
+
+@pytest.mark.parametrize(
+    "mode, mock_data, expected_calls",
+    [
+        (
+            "add",
+            np.zeros(5),
+            [{"sub_type": "device_monitor_1d", "value": np.zeros(5)}, {"value": np.zeros(5)}],
+        )
+    ],
+)
+def test_waveform_update_modes(waveform, mode, mock_data, expected_calls):
+    """Test the add and add_slice update modes of the SimWaveform class"""
+    waveform.sim.select_model("GaussianModel")
+    waveform.sim.params = {"amplitude": 500, "center": 500, "sigma": 10}
+    with pytest.raises(ValueError):
+        waveform.async_update.put("invalid_mode")
+    # Use add mode
+    waveform.async_update.put(mode)
+    with (
+        mock.patch.object(waveform, "_run_subs") as mock_run_subs,
+        mock.patch.object(waveform, "_send_async_update") as mock_send_async_update,
+        mock.patch.object(waveform.waveform, "get", return_value=mock_data),
+    ):
+
+        status = waveform.trigger()
+        status_wait(status, timeout=10)  # Raise if times out
+        assert status.done is True
+        # Run subs
+        assert mock_run_subs.call_args[1]["sub_type"] == expected_calls[0]["sub_type"]
+        assert np.array_equal(mock_run_subs.call_args[1]["value"], expected_calls[0]["value"])
+        # Send async update
+        assert np.array_equal(
+            mock_send_async_update.call_args[1]["value"], expected_calls[1]["value"]
+        )
+
+
+@pytest.mark.parametrize(
+    "mode, index, expected_md",
+    [
+        (
+            "add_slice",
+            0,
+            {"async_update": {"type": "add_slice", "index": 0, "max_shape": [None, 100]}},
+        ),
+        ("add_slice", None, {"async_update": {"type": "add", "max_shape": [None, 100]}}),
+        ("add", 0, {"async_update": {"type": "add", "max_shape": [None]}}),
+    ],
+)
+def test_waveform_send_async_update(waveform, mode, index, expected_md):
+    """Test the send_async_update method of SimWaveform."""
+    max_shape = expected_md["async_update"]["max_shape"]
+    if len(max_shape) > 1:
+        wv_shape = max_shape[1]
+    else:
+        wv_shape = 100
+    waveform.waveform_shape.put(wv_shape)
+    waveform.async_update.put(mode)
+    waveform.scan_info = get_mock_scan_info(device=waveform)
+    value = 0
+    with mock.patch.object(waveform.connector, "xadd") as mock_xadd:
+        waveform._send_async_update(index=index, value=value)
+        # Check here that metadata is properly set
+        args, kwargs = mock_xadd.call_args
+        msg = args[1]["data"]
+        assert msg.metadata == expected_md