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fix cryomagnetics4g driver bug. #7114

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fix cryomagnetics4g driver bug. #7114

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67a9a3d
fix cryomagnetics4g driver bug.
liuyichao82 Apr 30, 2025
23a30fc
Add a short description.
liuyichao82 Apr 30, 2025
1a7a1be
reword change Document of the Cryomagnetics4G driver. Improve the code.
liuyichao82 May 9, 2025
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4 changes: 4 additions & 0 deletions docs/changes/newsfragments/7114.improved_driver
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Original file line number Diff line number Diff line change
@@ -0,0 +1,4 @@
1. Added missing initialization of `self._RETRY_WRITE_ASK` and `self._RETRY_TIME` in the `write_raw` method to handle communication retries on VisaIOError.
2. Updated `set_field` to correctly recognize Standby as a valid final state when setting the magnetic field to 0 T.
3. Modified `wait_while_ramping` to check the actual magnetic field value via `self._get_field()` instead of relying on the status byte, since the instrument may stay in the Ramping state even after reaching the target field.
4. Fixed unit parsing to handle unexpected trailing characters in the instrument's response. (e.g., "\r").
11 changes: 7 additions & 4 deletions src/qcodes/instrument_drivers/cryomagnetics/_cryomagnetics4g.py
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Original file line number Diff line number Diff line change
Expand Up @@ -72,6 +72,9 @@ def __init__(
coil_constant: float,
**kwargs: Unpack[VisaInstrumentKWArgs],
):
self._RETRY_WRITE_ASK = True
self._RETRY_TIME = 1

super().__init__(name, address, **kwargs)

self.coil_constant = coil_constant
Expand Down Expand Up @@ -298,7 +301,7 @@ def set_field(self, field_setpoint: float, block: bool = True) -> None:
self.log.debug("Finished blocking ramp")
# If we are now holding, it was successful

if not exit_state.holding:
if not exit_state.standby and not exit_state.holding:
msg = "_set_field({}) failed with state: {}"
raise Cryomagnetics4GException(msg.format(field_setpoint, exit_state))

Expand All @@ -307,8 +310,8 @@ def wait_while_ramping(
) -> CryomagneticsOperatingState:
"""Waits while the magnet is ramping, checking the status byte instead of field value."""
while True:
status_byte = int(self.ask("*STB?"))
if not bool(status_byte & 1): # Check if ramping bit is clear
current_field = self._get_field()
if abs(value - current_field) < 1e-4:
break
self._sleep(self.ramping_state_check_interval())
self.write("SWEEP PAUSE")
Expand Down Expand Up @@ -355,7 +358,7 @@ def _get_field(self) -> float:
)

# Return value in Tesla, only converting if necessary
if self.units() == "T":
if self.units().strip() == "T":
return numeric_value * self.KG_TO_TESLA
else:
return numeric_value
Expand Down
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