diff --git a/apstools/devices/__init__.py b/apstools/devices/__init__.py
index bb62f5177..ae8598863 100644
--- a/apstools/devices/__init__.py
+++ b/apstools/devices/__init__.py
@@ -17,8 +17,7 @@
 
 from .aps_machine import ApsMachineParametersDevice
 
-from .aps_undulator import ApsUndulator
-from .aps_undulator import ApsUndulatorDual
+from .aps_undulator import PlanarUndulator
 
 from .area_detector_support import AD_EpicsFileNameMixin
 from .area_detector_support import AD_FrameType_schemes
diff --git a/apstools/devices/aps_undulator.py b/apstools/devices/aps_undulator.py
index 2f556740f..0a62883b4 100644
--- a/apstools/devices/aps_undulator.py
+++ b/apstools/devices/aps_undulator.py
@@ -8,81 +8,93 @@
    ~ApsUndulatorDual
 """
 
+import logging
+from enum import IntEnum
+
 from ophyd import Component
+from ophyd import DerivedSignal
 from ophyd import Device
 from ophyd import EpicsSignal
 from ophyd import EpicsSignalRO
+from ophyd import PVPositioner
 from ophyd import Signal
 
 from .tracking_signal import TrackingSignal
 
+logger = logging.getLogger(__name__)
 
-class ApsUndulator(Device):
-    """
-    APS Undulator
 
-    .. index:: Ophyd Device; ApsUndulator
+class DoneStatus(IntEnum):
+    MOVING = 0
+    DONE = 1
 
-    EXAMPLE::
 
-        undulator = ApsUndulator("ID09ds:", name="undulator")
-    """
+class BusyStatus(IntEnum):
+    DONE = 0
+    BUSY = 1
+
+
+class MotorDriveStatus(IntEnum):
+    NOT_READY = 0
+    READY_TO_MOVE = 1
+
+
+class UndulatorPositioner(PVPositioner):
+    """A positioner for any of the gap control parameters.
+
+    Communicates with the parent (presumably the undulator device) to
+    start and stop the device.
 
-    energy = Component(
-        EpicsSignal,
-        "Energy",
-        write_pv="EnergySet",
-        put_complete=True,
-        kind="hinted",
-    )
-    energy_taper = Component(
-        EpicsSignal,
-        "TaperEnergy",
-        write_pv="TaperEnergySet",
-        kind="config",
-    )
-    gap = Component(EpicsSignal, "Gap", write_pv="GapSet")
-    gap_taper = Component(EpicsSignal, "TaperGap", write_pv="TaperGapSet", kind="config")
-    start_button = Component(EpicsSignal, "Start", put_complete=True, kind="omitted")
-    stop_button = Component(EpicsSignal, "Stop", kind="omitted")
-    harmonic_value = Component(EpicsSignal, "HarmonicValue", kind="config")
-    gap_deadband = Component(EpicsSignal, "DeadbandGap", kind="config")
-    device_limit = Component(EpicsSignal, "DeviceLimit", kind="config")
-
-    access_mode = Component(EpicsSignalRO, "AccessSecurity", kind="omitted")
-    device_status = Component(EpicsSignalRO, "Busy", kind="omitted")
-    total_power = Component(EpicsSignalRO, "TotalPower", kind="config")
-    message1 = Component(EpicsSignalRO, "Message1", kind="omitted")
-    message2 = Component(EpicsSignalRO, "Message2", kind="omitted")
-    message3 = Component(EpicsSignalRO, "Message3", kind="omitted")
-    time_left = Component(EpicsSignalRO, "ShClosedTime", kind="omitted")
-
-    device = Component(EpicsSignalRO, "Device", kind="config")
-    location = Component(EpicsSignalRO, "Location", kind="config")
-    version = Component(EpicsSignalRO, "Version", kind="config")
-
-    # Useful undulator parameters that are not EPICS PVs.
-    energy_deadband = Component(Signal, value=0.0, kind="config")
-    energy_backlash = Component(Signal, value=0.0, kind="config")
-    energy_offset = Component(Signal, value=0, kind="config")
-    tracking = Component(TrackingSignal, value=False, kind="config")
-
-
-class ApsUndulatorDual(Device):
     """
-    APS Undulator with upstream *and* downstream controls
 
-    .. index:: Ophyd Device; ApsUndulatorDual
+    setpoint = Component(EpicsSignal, "SetC.VAL")
+    readback = Component(EpicsSignalRO, "M.VAL")
+
+    actuate = Component(DerivedSignal, derived_from="parent.start_button", kind="omitted")
+    stop_signal = Component(DerivedSignal, derived_from="parent.stop_button", kind="omitted")
+    done = Component(DerivedSignal, derived_from="parent.done", kind="omitted")
+    done_value = DoneStatus.DONE
+
+
+class PlanarUndulator(Device):
+    """APS Planar Undulator.
+
+    .. index:: Ophyd Device; PlanarUndulator
+
+    The signals *busy* and *done* convey complementary
+    information. *busy* comes from the IOC, while *done* comes
+    directly from the controller.
 
     EXAMPLE::
 
-        undulator = ApsUndulatorDual("ID09", name="undulator")
+        undulator = PlanarUndulator("S25ID:USID:", name="undulator")
 
-    note:: the trailing ``:`` in the PV prefix should be omitted
     """
 
-    upstream = Component(ApsUndulator, "us:")
-    downstream = Component(ApsUndulator, "ds:")
+    # X-ray spectrum parameters
+    energy = Component(UndulatorPositioner, "Energy")
+    energy_taper = Component(UndulatorPositioner, "TaperEnergy")
+    gap = Component(UndulatorPositioner, "Gap")
+    gap_taper = Component(UndulatorPositioner, "TaperGap")
+    harmonic_value = Component(EpicsSignal, "HarmonicValueC", kind="config")
+    total_power = Component(EpicsSignalRO, "TotalPowerM.VAL", kind="config")
+    # Signals for moving the undulator
+    start_button = Component(EpicsSignal, "StartC.VAL", put_complete=True, kind="omitted")
+    stop_button = Component(EpicsSignal, "StopC.VAL", kind="omitted")
+    busy = Component(EpicsSignalRO, "BusyM.VAL", kind="omitted")
+    done = Component(EpicsSignalRO, "BusyDeviceM.VAL", kind="omitted")
+    motor_drive_status = Component(EpicsSignalRO, "MotorDriveStatusM.VAL", kind="omitted")
+    # Miscellaneous control signals
+    gap_deadband = Component(EpicsSignal, "DeadbandGapC", kind="config")
+    device_limit = Component(EpicsSignal, "DeviceLimitM.VAL", kind="config")
+    access_mode = Component(EpicsSignalRO, "AccessSecurityC", kind="omitted")
+    message1 = Component(EpicsSignalRO, "Message1M.VAL", kind="omitted")
+    message2 = Component(EpicsSignalRO, "Message2M.VAL", kind="omitted")
+    device = Component(EpicsSignalRO, "DeviceM", kind="config")
+    magnet = Component(EpicsSignalRO, "DeviceMagnetM", kind="config")
+    location = Component(EpicsSignalRO, "LocationM", kind="config")
+    version_plc = Component(EpicsSignalRO, "PLCVersionM.VAL", kind="config")
+    version_hpmu = Component(EpicsSignalRO, "HPMUVersionM.VAL", kind="config")
 
 
 # -----------------------------------------------------------------------------
diff --git a/apstools/devices/tests/test_aps_undulator.py b/apstools/devices/tests/test_aps_undulator.py
new file mode 100644
index 000000000..66c535cdf
--- /dev/null
+++ b/apstools/devices/tests/test_aps_undulator.py
@@ -0,0 +1,23 @@
+import pytest
+from ophyd.sim import instantiate_fake_device
+
+from ..aps_undulator import PlanarUndulator
+
+
+@pytest.fixture()
+def undulator():
+    undulator = instantiate_fake_device(PlanarUndulator, prefix="PSS:255ID:", name="undulator")
+    return undulator
+
+
+def test_set_energy(undulator):
+    assert undulator.start_button.get() == 0
+    undulator.energy.set(5)
+    assert undulator.energy.setpoint.get() == 5
+    assert undulator.start_button.get() == 1
+
+
+def test_stop_energy(undulator):
+    assert undulator.stop_button.get() == 0
+    undulator.stop()
+    assert undulator.stop_button.get() == 1