# Lake Shore 421 Gaussmeter

class pymeasure.instruments.lakeshore.LakeShore421(adapter, name='Lake Shore 421 Gaussmeter', baud_rate=9600, **kwargs)

  Bases: `Instrument`

  Represents the Lake Shore 421 Gaussmeter and provides a high-level interface for interacting with the instrument.

      gaussmeter = LakeShore421("COM1")
      gaussmeter.unit = "T"               # Set units to Tesla
      gaussmeter.auto_range = True        # Turn on auto-range
      gaussmeter.fast_mode = True         # Turn on fast-mode

  A delay of 50 ms is ensured between subsequent writes, as the instrument cannot correctly handle writes any faster.

  property alarm_active

    A boolean property that returns whether the alarm is triggered.

  property alarm_audible

    A boolean property that enables or disables the audible alarm beeper.

  property alarm_high

    Property that controls the upper setpoint for the alarm mode in the current units. This takes into account the field multiplier.

  property alarm_high_multiplier

    Returns the multiplier for the upper alarm setpoint field.

  property alarm_high_raw

    ALMH %g

  property alarm_in_out

    A string property that controls whether an active alarm is caused when the field reading is inside (“Inside”) or outside (“Outside”) of the high and low setpoint values.

  property alarm_low

    Property that controls the lower setpoint for the alarm mode in the current units. This takes into account the field multiplier.

  property alarm_low_multiplier

    Returns the multiplier for the lower alarm setpoint field.

  property alarm_low_raw

    ALML %g

  property alarm_mode_enabled

    A boolean property that enables or disables the alarm mode.

  property alarm_sort_enabled

    A boolean property that enables or disables the alarm Sort Pass/Fail function.

  property auto_range

    A boolean property that controls the auto-range option of the meter. Valid values are True and False. Note that the auto-range is relatively slow and might not suffice for rapid measurements.

  property display_filter_enabled

    A boolean property that controls the display filter to make it more readable when the probe is exposed to a noisy field. The filter function makes a linear average of 8 readings and settles in approximately 2 seconds.

  property fast_mode

    A boolean property that controls the fast-mode option of the meter. Valid values are True and False. When enabled, the relative mode, Max Hold mode, alarms, and autorange are disabled.

  property field

    Returns the field in the current units. This property takes into account the field multiplier. Returns np.nan if field is out of range.

  property field_mode

    A string property that controls whether the gaussmeter measures AC or DC magnetic fields. Valid values are “AC” and “DC”.

  property field_multiplier

    Returns the field multiplier for the returned magnetic field.

  property field_range

    A floating point property that controls the field range of the meter in the current unit (G or T). Valid values are 30e3, 3e3, 300, 30 (when in Gauss), or 0.003, 0.03, 0.3, and 3 (when in Tesla).

  property field_range_raw

    A integer property that controls the field range of the meter. Valid values are 0 (highest) to 3 (lowest).

  property field_raw

    Returns the field in the current units and multiplier

  property front_panel_brightness

    An integer property that controls the brightness of the from panel display. Valid values are 0 (dimmest) to 7 (brightest).

  property front_panel_locked

    A boolean property that locks or unlocks all front panel entries except pressing the Alarm key to silence alarms.

  property max_hold_enabled

    A boolean property that enables or disables the Max Hold function to store the largest field since the last reset (with max_hold_reset).

  property max_hold_field

    Returns the largest field since the last reset in the current units. This property takes into account the field multiplier. Returns np.nan if field is out of range.

  property max_hold_field_raw

    Returns the largest field since the last reset in the current units and multiplier.

  property max_hold_multiplier

    Returns the multiplier for the returned max hold field.

  max_hold_reset()

    Clears the stored Max Hold value.

  property probe_type

    Returns type of field-probe used with the gaussmeter. Possible values are High Sensitivity, High Stability, or Ultra-High Sensitivity.

  property relative_field

    Returns the relative field in the current units. This property takes into account the field multiplier. Returns np.nan if field is out of range.

  property relative_field_raw

    Returns the relative field in the current units and the current multiplier.

  property relative_mode_enabled

    A boolean property that enables or disables the relative mode to see small variations with respect to a given setpoint.

  property relative_multiplier

    Returns the relative field multiplier for the returned magnetic field.

  property relative_setpoint

    Property that controls the setpoint for the relative field mode in the current units. This takes into account the field multiplier.

  property relative_setpoint_multiplier

    Returns the multiplier for the setpoint field.

  property relative_setpoint_raw

    Property that controls the setpoint for the relative field mode in the current units and multiplier.

  property serial_number

    Returns the serial number of the probe.

  shutdown()

    Closes the serial connection to the system.

  property unit

    A string property that controls the units used by the gaussmeter. Valid values are G (Gauss), T (Tesla).

  write(command)

    Write a string command to the instrument appending write_termination.

    Parameters:

      - command – command string to be sent to the instrument

      - kwargs – Keyword arguments for the adapter.

  zero_probe(wait=True)

    Reset the probe value to 0. It is normally used with a zero gauss chamber, but may also be used with an open probe to cancel the Earth magnetic field. To cancel larger magnetic fields, the relative mode should be used.

    Parameters:

      wait (bool) – Wait for 20 seconds after issuing the command to allow the resetting to finish.