diff --git a/malcolm/parts/ADCore/hdfwriterpart.py b/malcolm/parts/ADCore/hdfwriterpart.py
index bb165cb3c..37480833d 100644
--- a/malcolm/parts/ADCore/hdfwriterpart.py
+++ b/malcolm/parts/ADCore/hdfwriterpart.py
@@ -53,11 +53,12 @@ def _create_dataset_infos(self, part_info, generator, filename):
         primary_infos = self._get_dataset_infos(part_info, primary=True)
 
         # Add the primary datasource
+        generator_rank = len(generator.index_dims)
         if primary_infos:
             dataset_info = primary_infos[0]
             ret.append(DatasetProducedInfo(
                 name="%s.data" % dataset_info.name, filename=filename,
-                type=dataset_info.type, rank=dataset_info.rank,
+                type=dataset_info.type, rank=dataset_info.rank + generator_rank,
                 path="/entry/detector/detector",
                 uniqueid=uniqueid))
 
@@ -69,18 +70,20 @@ def _create_dataset_infos(self, part_info, generator, filename):
                 assert primary_infos, \
                     "Needed a primary dataset for secondary"
                 name = "%s.%s" % (primary_infos[0].name, dataset_info.name)
+                rank = primary_infos[0].rank + generator_rank
             else:
                 # something like x.value or izero
                 name = dataset_info.name
+                rank = dataset_info.rank + generator_rank
             ret.append(DatasetProducedInfo(
                 name=name, filename=filename, type=dataset_info.type,
-                rank=dataset_info.rank, path=path, uniqueid=uniqueid))
+                rank=rank, path=path, uniqueid=uniqueid))
 
         # Add any setpoint dimensions
         for dim in generator.axes:
             ret.append(DatasetProducedInfo(
                 name="%s.value_set" % dim, filename=filename,
-                type="position_set", rank=0,
+                type="position_set", rank=1,
                 path="/entry/detector/%s_set" % dim, uniqueid=""))
         return ret
 
@@ -247,6 +250,9 @@ def _make_layout_xml(self, generator, part_info):
                       source="constant", value="SDS", type="string")
         # Now add some additional sources of data
         for dataset_info in self._get_dataset_infos(part_info, primary=False):
+            # if we are a secondary source, use the same rank as the det
+            if dataset_info.type == "secondary":
+                dataset_info.rank = primary_rank
             attr_el = self._make_nxdata(
                 dataset_info, entry_el, generator, link=True)
             ET.SubElement(attr_el, "dataset", name=dataset_info.name,
diff --git a/tests/test_parts/test_ADCore/test_hdfwriterpart.py b/tests/test_parts/test_ADCore/test_hdfwriterpart.py
index a033251b4..7896a4aff 100644
--- a/tests/test_parts/test_ADCore/test_hdfwriterpart.py
+++ b/tests/test_parts/test_ADCore/test_hdfwriterpart.py
@@ -47,33 +47,33 @@ def test_configure(self):
         self.assertEquals(infos[0].name, "xspress3.data")
         self.assertEquals(infos[0].filename, "file.h5")
         self.assertEquals(infos[0].type, "primary")
-        self.assertEquals(infos[0].rank, 2)
+        self.assertEquals(infos[0].rank, 4)
         self.assertEquals(infos[0].path, "/entry/detector/detector")
         self.assertEquals(infos[0].uniqueid,
                           "/entry/NDAttributes/NDArrayUniqueId")
         self.assertEquals(infos[1].name, "xspress3.sum")
         self.assertEquals(infos[1].filename, "file.h5")
         self.assertEquals(infos[1].type, "secondary")
-        self.assertEquals(infos[1].rank, 0)
+        self.assertEquals(infos[1].rank, 4)
         self.assertEquals(infos[1].path, "/entry/sum/sum")
         self.assertEquals(infos[1].uniqueid,
                           "/entry/NDAttributes/NDArrayUniqueId")
         self.assertEquals(infos[2].name, "energy.value_set")
         self.assertEquals(infos[2].filename, "file.h5")
         self.assertEquals(infos[2].type, "position_set")
-        self.assertEquals(infos[2].rank, 0)
+        self.assertEquals(infos[2].rank, 1)
         self.assertEquals(infos[2].path, "/entry/detector/energy_set")
         self.assertEquals(infos[2].uniqueid, "")
         self.assertEquals(infos[3].name, "x.value_set")
         self.assertEquals(infos[3].filename, "file.h5")
         self.assertEquals(infos[3].type, "position_set")
-        self.assertEquals(infos[3].rank, 0)
+        self.assertEquals(infos[3].rank, 1)
         self.assertEquals(infos[3].path, "/entry/detector/x_set")
         self.assertEquals(infos[3].uniqueid, "")
         self.assertEquals(infos[4].name, "y.value_set")
         self.assertEquals(infos[4].filename, "file.h5")
         self.assertEquals(infos[4].type, "position_set")
-        self.assertEquals(infos[4].rank, 0)
+        self.assertEquals(infos[4].rank, 1)
         self.assertEquals(infos[4].path, "/entry/detector/y_set")
         self.assertEquals(infos[4].uniqueid, "")
         self.assertEqual(task.put.call_args_list, [
@@ -141,7 +141,7 @@ def test_configure(self):
 </group>
 <group name="sum">
 <attribute name="signal" source="constant" type="string" value="sum" />
-<attribute name="axes" source="constant" type="string" value="energy_set,." />
+<attribute name="axes" source="constant" type="string" value="energy_set,.,.,." />
 <attribute name="NX_class" source="constant" type="string" value="NXdata" />
 <attribute name="energy_set_indices" source="constant" type="string" value="0" />
 <hardlink name="energy_set" target="/entry/detector/energy_set" />