Test Automation

Test Equipment Automation Skill

Automated test equipment control and data acquisition for hardware validation and characterization.

Purpose

This skill provides comprehensive capabilities for automating electronic test equipment, enabling consistent and repeatable hardware validation workflows. It supports instrument communication, automated test sequences, data logging, and analysis.

Capabilities

Instrument Communication

• VISA/SCPI instrument communication protocols
• Support for GPIB, USB-TMC, LAN/VXI-11, and serial interfaces
• Instrument discovery and resource management
• Error handling and timeout management
• Connection pooling for multi-instrument setups

Oscilloscope Automation

• Keysight, Tektronix, Rohde & Schwarz oscilloscope control
• Channel configuration and coupling
• Trigger setup (edge, pulse, pattern, serial)
• Waveform acquisition and transfer
• Measurement extraction (rise time, frequency, duty cycle)
• Screenshot capture and documentation

Spectrum Analyzer Control

• Frequency span and center frequency configuration
• Resolution and video bandwidth settings
• Marker operations and peak search
• Trace capture and data export
• Limit line testing and pass/fail determination
• EMC pre-compliance measurements

Power Supply and Electronic Load Control

• Output voltage and current programming
• Protection limit configuration
• Sequencing and timing control
• Load transient generation
• Efficiency measurement automation

DMM and SMU Automation

• DC/AC voltage and current measurements
• Resistance and continuity testing
• Source-measure unit (SMU) operations
• IV curve characterization
• Temperature coefficient measurements

Data Logging and Analysis

• Real-time data acquisition
• Statistical analysis (mean, std, min, max)
• Data logging to CSV, JSON, HDF5
• Time-series trending
• Alarm and limit monitoring

Test Sequence Scripting

• Sequential and parallel test execution
• Conditional branching based on results
• Loop and iteration support
• Test fixture abstraction
• Parameterized test cases

Measurement Uncertainty Analysis

• Type A (statistical) uncertainty evaluation
• Type B (systematic) uncertainty estimation
• Combined uncertainty calculation
• Coverage factor and confidence intervals
• GUM-compliant uncertainty budgets

Report Generation

• Automated test report creation
• Pass/fail summary tables
• Measurement data visualization
• Traceability documentation
• Export to PDF, HTML, Excel formats

Prerequisites

Installation

pip install pyvisa pyvisa-py numpy pandas matplotlib

Optional Dependencies

# For HDF5 data storage
pip install h5py tables

# For advanced analysis
pip install scipy uncertainties

# For report generation
pip install jinja2 weasyprint

Usage Patterns

Basic Instrument Communication

import pyvisa

# Initialize resource manager
rm = pyvisa.ResourceManager()

# List available instruments
print(rm.list_resources())

# Connect to oscilloscope
scope = rm.open_resource('TCPIP::192.168.1.100::INSTR')
scope.timeout = 5000  # 5 second timeout

# Query identification
idn = scope.query('*IDN?')
print(f"Connected to: {idn}")

# Configure and measure
scope.write(':CHANnel1:DISPlay ON')
scope.write(':CHANnel1:SCALe 1.0')  # 1V/div
scope.write(':TIMebase:SCALe 0.001')  # 1ms/div
scope.write(':TRIGger:EDGE:SOURce CHANnel1')
scope.write(':TRIGger:EDGE:LEVel 0.5')

# Read measurement
vpp = float(scope.query(':MEASure:VPP? CHANnel1'))
freq = float(scope.query(':MEASure:FREQuency? CHANnel1'))

print(f"Vpp: {vpp:.3f} V, Frequency: {freq:.2f} Hz")

scope.close()

Automated Test Sequence

from dataclasses import dataclass
from typing import List, Dict, Any
import time

@dataclass
class TestResult:
    name: str
    passed: bool
    value: float
    unit: str
    limit_low: float
    limit_high: float

class TestSequence:
    def __init__(self, instruments: Dict[str, Any]):
        self.instruments = instruments
        self.results: List[TestResult] = []

    def run_test(self, name: str, measure_func, limit_low: float,
                 limit_high: float, unit: str) -> TestResult:
        value = measure_func()
        passed = limit_low <= value <= limit_high
        result = TestResult(name, passed, value, unit, limit_low, limit_high)
        self.results.append(result)
        return result

    def generate_report(self) -> Dict:
        return {
            'total_tests': len(self.results),
            'passed': sum(1 for r in self.results if r.passed),
            'failed': sum(1 for r in self.results if not r.passed),
            'results': [vars(r) for r in self.results]
        }

# Example usage
def measure_output_voltage():
    return float(dmm.query(':MEASure:VOLTage:DC?'))

sequence = TestSequence({'dmm': dmm, 'psu': psu})
sequence.run_test('Output Voltage', measure_output_voltage, 4.9, 5.1, 'V')

Measurement Uncertainty Analysis

from uncertainties import ufloat
import numpy as np

class UncertaintyAnalysis:
    def __init__(self):
        self.measurements = []
        self.instrument_uncertainty = 0.0

    def add_measurement(self, value: float):
        self.measurements.append(value)

    def set_instrument_uncertainty(self, uncertainty: float):
        """Set Type B uncertainty from instrument specifications"""
        self.instrument_uncertainty = uncertainty

    def calculate_combined_uncertainty(self, coverage_factor: float = 2.0):
        # Type A uncertainty (statistical)
        n = len(self.measurements)
        mean = np.mean(self.measurements)
        std = np.std(self.measurements, ddof=1)
        type_a = std / np.sqrt(n)

        # Type B uncertainty
        type_b = self.instrument_uncertainty / np.sqrt(3)  # Rectangular distribution

        # Combined standard uncertainty
        combined = np.sqrt(type_a**2 + type_b**2)

        # Expanded uncertainty
        expanded = coverage_factor * combined

        return {
            'mean': mean,
            'type_a_uncertainty': type_a,
            'type_b_uncertainty': type_b,
            'combined_uncertainty': combined,
            'expanded_uncertainty': expanded,
            'coverage_factor': coverage_factor
        }

# Usage
analysis = UncertaintyAnalysis()
for _ in range(10):
    analysis.add_measurement(float(dmm.query(':MEASure:VOLTage:DC?')))
analysis.set_instrument_uncertainty(0.001)  # 1mV from spec sheet
result = analysis.calculate_combined_uncertainty()
print(f"Voltage: {result['mean']:.4f} +/- {result['expanded_uncertainty']:.4f} V (k=2)")

Usage Guidelines

When to Use This Skill

• Automated hardware validation and characterization
• Production test development
• Design verification testing
• Environmental testing with data acquisition
• EMC pre-compliance measurements

Best Practices

1. Always verify instrument connections before starting test sequences
2. Use appropriate timeouts for slow measurements
3. Implement proper error handling for instrument communication failures
4. Document measurement conditions (temperature, humidity, setup)
5. Include calibration verification in test procedures
6. Use statistical analysis for production testing decisions

Process Integration

• ee-hardware-validation (all phases)
• ee-environmental-testing (data acquisition)
• ee-emc-design-testing (pre-compliance measurements)

Dependencies

• PyVISA and PyVISA-py for instrument communication
• NI VISA or Keysight IO Libraries for driver support
• Instrument-specific drivers as needed

References

• PyVISA Documentation
• SCPI Standard Reference
• GUM Uncertainty Guide