diff --git a/src/fixate/drivers/dmm/keithley_6500.py b/src/fixate/drivers/dmm/keithley_6500.py
index 5d0acd9..9fe3813 100644
--- a/src/fixate/drivers/dmm/keithley_6500.py
+++ b/src/fixate/drivers/dmm/keithley_6500.py
@@ -40,14 +40,15 @@ def __init__(self, instrument, *args, **kwargs):
             "continuity": "CONT",
             "diode": "DIOD",
         }
+        # note: the keithley 6500 also supports changing NPLC for diode measurements, but this has been removed as the fluke does not support it.
         self._nplc_modes = [
             "voltage_dc",
             "current_dc",
             "resistance",
             "fresistance",
-            "diode",
             "temperature",
         ]
+        # note: the keithley supports setting NPLC to any value between 0.0005 and 12 (with 50hz mains power) but for compatibility with the fluke, we only support the following values
         self._nplc_settings = [0.02, 0.2, 1, 10]
         self._nplc_default = 1
         self._init_string = ""  # Unchanging
diff --git a/test/drivers/test_fluke_8846A.py b/test/drivers/test_fluke_8846A.py
index da8b748..98da3f7 100644
--- a/test/drivers/test_fluke_8846A.py
+++ b/test/drivers/test_fluke_8846A.py
@@ -323,6 +323,9 @@ def test_measurement_diode(funcgen, dmm, rm):
         ("current_dc"),
         ("resistance"),
         ("fresistance"),
+        pytest.param(
+            "diode", marks=pytest.mark.xfail(raises=ParameterError, strict=True)
+        ),
         pytest.param(
             "voltage_ac", marks=pytest.mark.xfail(raises=ParameterError, strict=True)
         ),
@@ -358,6 +361,9 @@ def test_get_nplc(mode, dmm):
         ("current_dc"),
         ("resistance"),
         ("fresistance"),
+        pytest.param(
+            "diode", marks=pytest.mark.xfail(raises=ParameterError, strict=True)
+        ),
         pytest.param(
             "voltage_ac", marks=pytest.mark.xfail(raises=ParameterError, strict=True)
         ),
@@ -401,6 +407,9 @@ def test_set_nplc(mode, dmm):
         ("current_dc"),
         ("resistance"),
         ("fresistance"),
+        pytest.param(
+            "diode", marks=pytest.mark.xfail(raises=ParameterError, strict=True)
+        ),
         pytest.param(
             "voltage_ac", marks=pytest.mark.xfail(raises=ParameterError, strict=True)
         ),
diff --git a/test/drivers/test_keithley_6500.py b/test/drivers/test_keithley_6500.py
index 1976147..0481b2e 100644
--- a/test/drivers/test_keithley_6500.py
+++ b/test/drivers/test_keithley_6500.py
@@ -329,9 +329,11 @@ def test_measurement_diode(funcgen, dmm, rm):
     [
         ("voltage_dc"),
         ("current_dc"),
-        ("diode"),
         ("resistance"),
         ("fresistance"),
+        pytest.param(
+            "diode", marks=pytest.mark.xfail(raises=ParameterError, strict=True)
+        ),
         pytest.param(
             "voltage_ac", marks=pytest.mark.xfail(raises=ParameterError, strict=True)
         ),
@@ -365,9 +367,11 @@ def test_get_nplc(mode, dmm):
     [
         ("voltage_dc"),
         ("current_dc"),
-        ("diode"),
         ("resistance"),
         ("fresistance"),
+        pytest.param(
+            "diode", marks=pytest.mark.xfail(raises=ParameterError, strict=True)
+        ),
         pytest.param(
             "voltage_ac", marks=pytest.mark.xfail(raises=ParameterError, strict=True)
         ),
@@ -409,9 +413,11 @@ def test_set_nplc(mode, dmm):
     [
         ("voltage_dc"),
         ("current_dc"),
-        ("diode"),
         ("resistance"),
         ("fresistance"),
+        pytest.param(
+            "diode", marks=pytest.mark.xfail(raises=ParameterError, strict=True)
+        ),
         pytest.param(
             "voltage_ac", marks=pytest.mark.xfail(raises=ParameterError, strict=True)
         ),