Merge pull request #8009 from jenshnielsen/ami_snapshot_fix

Ami snapshot fix

Author: jenshnielsen

docs/changes/newsfragments/8009.improved_driver

@@ -0,0 +1,4 @@
+The ``AMI430SwitchHeater`` snapshot now skips updating heater-specific parameters
+(``state``, ``in_persistent_mode``, ``current``, ``heat_time``, ``cool_time``) when
+the switch heater is not enabled. This prevents VISA query failures on real hardware
+when the heater is not installed.

src/qcodes/instrument_drivers/american_magnetics/AMI430_visa.py

@@ -6,7 +6,7 @@
 from collections.abc import Callable, Iterable, Sequence
 from contextlib import ExitStack
 from functools import partial
-from typing import TYPE_CHECKING, ClassVar, Concatenate, TypeVar, cast
+from typing import TYPE_CHECKING, Any, ClassVar, Concatenate, TypeVar, cast
 
 import numpy as np
 from pyvisa import VisaIOError
@@ -152,6 +152,32 @@ def _check_state(self) -> bool:
             return False
         return bool(int(self.ask("PS?").strip()))
 
+    def snapshot_base(
+        self,
+        update: bool | None = False,
+        params_to_skip_update: Sequence[str] | None = None,
+    ) -> dict[str, Any]:
+        if params_to_skip_update is None:
+            params_to_skip_update = []
+
+        if update is True:
+            enabled = self.enabled.get()
+        else:
+            enabled = self.enabled.cache.get()
+        if not enabled:
+            heater_params = [
+                "state",
+                "in_persistent_mode",
+                "current",
+                "heat_time",
+                "cool_time",
+            ]
+            params_to_skip_update = list(params_to_skip_update) + heater_params
+
+        return super().snapshot_base(
+            update=update, params_to_skip_update=params_to_skip_update
+        )
+
 
 class AMIModel430(VisaInstrument):
     _SHORT_UNITS: ClassVar[dict[str, str]] = {

tests/drivers/test_ami430_visa.py

@@ -1445,10 +1445,36 @@ def test_switch_heater_enabled(ami430: AMIModel430, caplog: LogCaptureFixture) -
     # make sure that getting snapshot with heater disabled works without warning
     caplog.clear()
     with caplog.at_level(logging.WARNING, logger=ami430.log.name):
-        ami430.snapshot(update=True)
+        snap = ami430.snapshot(update=True)
     assert len(caplog.records) == 0
+
+    # When heater is disabled, heater-specific parameters should not be updated
+    heater_snap = snap["submodules"]["switch_heater"]["parameters"]
+    for param_name in (
+        "state",
+        "in_persistent_mode",
+        "current",
+        "heat_time",
+        "cool_time",
+    ):
+        assert heater_snap[param_name]["ts"] is None, (
+            f"Parameter {param_name} should not have been updated when heater is disabled"
+        )
+
+    # When heater is enabled, snapshot should update all parameters
     ami430.switch_heater.enabled(True)
-    assert ami430.switch_heater.enabled() is True
+    snap_enabled = ami430.snapshot(update=True)
+    heater_snap_enabled = snap_enabled["submodules"]["switch_heater"]["parameters"]
+    for param_name in (
+        "state",
+        "in_persistent_mode",
+        "current",
+        "heat_time",
+        "cool_time",
+    ):
+        assert heater_snap_enabled[param_name]["ts"] is not None, (
+            f"Parameter {param_name} should have been updated when heater is enabled"
+        )
     ami430.switch_heater.enabled(False)
     assert ami430.switch_heater.enabled() is False