Running Measurements

PIEC organizes experiments as measurement classes — Python objects that bundle instrument configuration, waveform generation, and data analysis into a single run_experiment() call. This page explains the general workflow that applies to all measurement types.

General workflow

1. Initialize instruments

   Import and instantiate the driver(s) your measurement requires, passing each instrument’s VISA address:

   from piec.drivers.keysight81150a import Keysight81150a
   from piec.drivers.keysightdsox3024a import KeysightDSOX3024A
   
   awg = Keysight81150a('GPIB0::8::INSTR')
   osc = KeysightDSOX3024A('GPIB0::7::INSTR')
   

   Use 'virtual' as the address to run without hardware (see Connecting to the Instrument).

2. Create the measurement object

   Instantiate the measurement class with your instrument objects and experimental parameters:

   from piec.measurement import HysteresisLoop
   
   experiment = HysteresisLoop(
       awg=awg,
       osc=osc,
       frequency=1000.0,   # Hz
       amplitude=5.0,      # Volts
       n_cycles=3,
       area=1.0e-9,        # m²
       save_dir='./data',
   )
   

3. Run the experiment

   Call run_experiment() to execute the full measurement sequence:

   experiment.run_experiment()
   

   Internally this method:

   • Configures the instrument to output the required waveform.

   • Sets up the oscilloscope (timebase, channels, trigger).

   • Triggers the waveform and captures the response.

   • Saves the raw data to save_dir.

   • Calls analyze() to compute derived quantities and generate plots.

4. Inspect the output

   After run_experiment() completes, the saved data and any generated plots are in the directory you specified. See Data and Analysis for details on the file format and how to reload and post-process data.

Measurement class structure

All measurement classes follow the same pattern:

__init__(self, ...)

Accepts instrument objects and measurement parameters. Stores them as instance attributes but does not yet configure any hardware.

run_experiment(self)

Orchestrates the full measurement: configures instruments, runs the waveform/acquisition loop, saves data, and calls analyze().

configure_instrument(self)

Implemented by each concrete measurement class. Builds and sends the specific waveform (e.g., triangular sweep for hysteresis, pulse sequence for PUND) to the instrument.

analyze(self)

Implemented by each concrete measurement class. Reads the raw captured data, computes physical quantities (polarization, resistance, etc.), and generates plots.

For experiment-specific parameters and examples, see the individual measurement pages: Ferroelectric Measurement Documentation, AMR Measurement Documentation, DCIV Measurement Documentation.