Adding setting of ndattributes_file XML to the Xspress3Detector staging.

docs/topic_guides/fluorescence_detectors.rst

@@ -78,26 +78,11 @@ let Bluesky know which values are in the HDF5 file and where. The
 EPICS support for an Xspress3 detector provides several additional
 values besides the spectra, many of them useful for dead-time
 correction. These can be saved using the Ophyd-async NDAttribute
-support. Haven includes a function for generating these parameters so
-they can be set on the IOC in a way that allows Tiled to read the
-resulting values from the HDF5 file. This only needs to be done once
-for each detector IOC.
+support. The Xspress3 device support in Haven will generate these
+parameters and set them on the IOC during staging in a way that allows
+Tiled to read the resulting values from the HDF5 file alongside the
+image data itself.
 
-Be sure to **give this detector a name**, since it will be used as the
-column name in the database.
-
-.. code-block:: python
-
-    from haven.devices.detectors.xspress import Xspress3Detector, ndattribute_params
-    from ophyd_async.plan_stubs import setup_ndattributes
-    from bluesky import RunEngine
-
-    # Assuming a 4-element detector
-    RE = RunEngine()
-    detector = Xspress3Detector(...)
-    await detector.connect()
-    params = ndattribute_params(device_name=detector.name, elements=range(4))
-    RE(setup_ndattributes(detector.drv, params))
 
 .. note::
 
@@ -114,7 +99,7 @@ column name in the database.
 
 
 Why can't I…
-############
+============
 
 Previously, some steps were performed during data acquisition by the
 IOC that have now been moved to other parts of the system. These

src/haven/devices/detectors/xspress.py

@@ -1,4 +1,5 @@
 import asyncio
+import xml.etree.ElementTree as ET
 from collections.abc import Sequence
 
 from ophyd_async.core import (
@@ -17,7 +18,7 @@
     NDAttributeParam,
     convert_ad_dtype_to_np,
 )
-from ophyd_async.epics.core import epics_signal_rw, epics_signal_x
+from ophyd_async.epics.core import epics_signal_r, epics_signal_rw, epics_signal_x
 
 from .area_detectors import HavenDetector, default_path_provider
 
@@ -39,6 +40,7 @@ def __init__(self, prefix, name=""):
         self.erase_on_start = epics_signal_rw(bool, f"{prefix}EraseOnStart")
         self.erase = epics_signal_x(f"{prefix}ERASE")
         self.deadtime_correction = epics_signal_rw(bool, f"{prefix}CTRL_DTC")
+        self.number_of_elements = epics_signal_r(int, f"{prefix}MaxSizeY_RBV")
         super().__init__(prefix=prefix, name=name)
 
 
@@ -51,6 +53,14 @@ def get_deadtime(self, exposure: float) -> float:
         # include
         return 0.001
 
+    async def setup_ndattributes(self, device_name: str):
+        num_elements = await self._drv.number_of_elements.get_value()
+        params = ndattribute_params(
+            device_name=device_name, elements=range(num_elements)
+        )
+        xml = ndattribute_xml(params)
+        await self._drv.nd_attributes_file.set(xml)
+
     @AsyncStatus.wrap
     async def prepare(self, trigger_info: TriggerInfo):
         await asyncio.gather(
@@ -126,12 +136,40 @@ def __init__(
 
     @AsyncStatus.wrap
     async def stage(self) -> None:
-        await asyncio.gather(
+        self._old_xml_file, *_ = await asyncio.gather(
+            self.drv.nd_attributes_file.get_value(),
             super().stage(),
+            self._controller.setup_ndattributes(device_name=self.name),
             self.drv.erase_on_start.set(False),
             self.drv.erase.trigger(),
         )
 
+    @AsyncStatus.wrap
+    async def unstage(self) -> None:
+        await super().unstage()
+        if self._old_xml_file is not None:
+            # Restore the original XML attributes file
+            await self.drv.nd_attributes_file.set(self._old_xml_file)
+            self._old_xml_file = None
+
+
+def ndattribute_xml(params):
+    """Convert a set of NDAttribute params to XML."""
+    root = ET.Element("Attributes")
+    for ndattribute in params:
+        ET.SubElement(
+            root,
+            "Attribute",
+            name=ndattribute.name,
+            type="PARAM",
+            source=ndattribute.param,
+            addr=str(ndattribute.addr),
+            datatype=ndattribute.datatype.value,
+            description=ndattribute.description,
+        )
+    xml_text = ET.tostring(root, encoding="unicode")
+    return xml_text
+
 
 def ndattribute_params(
     device_name: str, elements: Sequence[int]

src/haven/tests/test_xspress.py

@@ -1,4 +1,5 @@
 import asyncio
+import xml.etree.ElementTree as ET
 from pathlib import Path
 
 import pytest
@@ -80,6 +81,22 @@ async def test_ndattribute_params():
     assert len(params) == n_elem * n_params
 
 
+async def test_stage_ndattributes(detector):
+    num_elem = 8
+    set_mock_value(detector.drv.number_of_elements, num_elem)
+    set_mock_value(detector.drv.nd_attributes_file, "XSP3.xml")
+    await detector.stage()
+    xml_mock = get_mock_put(detector.drv.nd_attributes_file)
+    assert xml_mock.called
+    # Test that the XML is correct
+    args, kwargs = xml_mock.call_args
+    tree = ET.fromstring(args[0])
+    assert len(tree) == num_elem * 9
+    # Check that the XML file gets reset when unstaged
+    await detector.unstage()
+    assert xml_mock.call_args[0][0] == "XSP3.xml"
+
+
 # -----------------------------------------------------------------------------
 # :author:    Mark Wolfman
 # :email:     [email protected]