HP 34401A Multimeter

class pymeasure.instruments.hp.HP34401A(adapter, name='HP 34401A', **kwargs)

Bases: SCPIUnknownMixin, Instrument

Represents the HP / Agilent / Keysight 34401A Multimeter and provides a high-level interface for interacting with the instrument.

dmm = HP34401A("GPIB::1")
dmm.function_ = "DCV"
print(dmm.reading)  # -> Single float reading

dmm.nplc = 0.02
dmm.autozero_enabled = False
dmm.trigger_count = 100
dmm.trigger_delay = "MIN"
print(dmm.reading)  # -> Array of 100 very fast readings
property auto_input_impedance_enabled

Control if automatic input resistance mode is enabled.

Only valid for dc voltage measurements. When disabled (default), the input resistance is fixed at 10 MOhms for all ranges. With AUTO ON, the input resistance is set to >10 GOhms for the 100 mV, 1 V, and 10 V ranges.

property autorange

Control the autorange state for the currently active function.

property autozero_enabled

Control the autozero state.


This command causes the multimeter to beep once.

property beeper_enabled

Control whether the beeper is enabled.

property current_ac

AC current, in Amps

Deprecated since version 0.12: Use the function_ and reading properties instead.

property current_dc

DC current, in Amps

Deprecated since version 0.12: Use the function_ and reading properties instead.

property detector_bandwidth

Control the lowest frequency expected in the input signal in Hertz.

Valid values: 3, 20, 200, “MIN”, “MAX”.

property display_enabled

Control the display state.

property displayed_text

Control the text displayed on the multimeter’s display.

The text can be up to 12 characters long; any additional characters are truncated my the multimeter.

property function_

Control the measurement function.

Allowed values: “DCV”, “DCV_RATIO”, “ACV”, “DCI”, “ACI”, “R2W”, “R4W”, “FREQ”, “PERIOD”, “CONTINUITY”, “DIODE”.

property gate_time

Control the gate time (or aperture time) for frequency or period measurements.

Valid values: 0.01, 0.1, 1, “MIN”, “MAX”. Specifically: 10 ms (4.5 digits), 100 ms (default; 5.5 digits), or 1 second (6.5 digits).


Set the state of the triggering system to “wait-for-trigger”.

Measurements will begin when the specified trigger conditions are satisfied after this command is received.

property nplc

Control the integration time in number of power line cycles (NPLC).

Valid values: 0.02, 0.2, 1, 10, 100, “MIN”, “MAX”. This command is valid only for dc volts, ratio, dc current, 2-wire ohms, and 4-wire ohms.

property range_

Control the range for the currently active function.

For frequency and period measurements, ranging applies to the signal’s input voltage, not its frequency

property reading

Take a measurement of the currently selected function.

Reading this property is equivalent to calling init_trigger(), waiting for completion and fetching the reading(s).

property remote_control_enabled

Control whether remote control is enabled.

property remote_lock_enabled

Control whether the beeper is enabled.

property resistance

Resistance, in Ohms

Deprecated since version 0.12: Use the function_ and reading properties instead.

property resistance_4w

Four-wires (remote sensing) resistance, in Ohms

Deprecated since version 0.12: Use the function_ and reading properties instead.

property resolution

Control the resolution of the measurements.

Not valid for frequency, period, or ratio. Specify the resolution in the same units as the measurement function, not in number of digits. Results in a “Settings Conflict” error if autorange is enabled. MIN selects the smallest value accepted, which gives the most resolution. MAX selects the largest value accepted which gives the least resolution.

property sample_count

Controls the number of samples per trigger event.

Valid values: 1 to 50000, “MIN”, “MAX”.

property scpi_version

The SCPI version of the multimeter.

property self_test_result

Initiate a self-test of the multimeter and return the result.

Be sure to set an appropriate connection timeout, otherwise the command will fail.

property stored_reading

Measure the reading(s) currently stored in the multimeter’s internal memory.

Reading this property will NOT initialize a trigger. If you need that, use the reading property instead.

property stored_readings_count

The number of readings currently stored in the internal memory.

property terminals_used

Query the multimeter to determine if the front or rear input terminals are selected.

Returns “FRONT” or “REAR”.

property trigger_auto_delay_enabled

Control the automatic trigger delay state.

If enabled, the delay is determined by function, range, integration time, and ac filter setting. Selecting a specific trigger delay value automatically turns off the automatic trigger delay.

property trigger_count

Control the number of triggers accepted before returning to the “idle” state.

Valid values: 1 to 50000, “MIN”, “MAX”, “INF”. The INFinite parameter instructs the multimeter to continuously accept triggers (you must send a device clear to return to the “idle” state).

property trigger_delay

Control the trigger delay in seconds.

Valid values (incl. floats): 0 to 3600 seconds, “MIN”, “MAX”.


Trigger an autozero measurement.

Consequent autozero measurements are disabled.

property trigger_source

Control the trigger source.

Valid values: “IMM”, “BUS”, “EXT” The multimeter will accept a software (bus) trigger, an immediate internal trigger (this is the default source), or a hardware trigger from the rear-panel Ext Trig (external trigger) terminal.

property voltage_ac

AC voltage, in Volts

Deprecated since version 0.12: Use the function_ and reading properties instead.


Write a command to the instrument.