Multi-Channel Timing Measurement with LabVIEW and NI Counter Hardware — MIL-STD-1553 Verification Example

#electronics #testing #labview #aerospace

Here's a practical implementation of MIL-STD-1553 bus timing verification using LabVIEW and NI PCIe counter hardware. The same architecture works for ARINC 429, radar timing, or any other repetitive timing measurement requirement.

Hardware Setup

MIL-STD-1553 Bus Under Test
    │
    ├── Bus Monitor (PCMILSTD or equivalent)
    │       └── Extracts timing data from 1553 protocol
    │
    └── Counter/Timer Card (NI PCIe-6612 or similar)
            ├── Channel 0: Measures RT response time
            ├── Channel 1: Measures word gap
            └── Channel 2: Measures message gap

LabVIEW Measurement Architecture

# Pseudocode representing LabVIEW dataflow structure

# Configure counter channels
configure_counter(channel=0, mode='TWO_EDGE_SEPARATION',
                  start_edge='RISING', end_edge='RISING',
                  timebase='100MHz')  # 10ns resolution

# Main measurement loop
results = []
for i in range(N_SAMPLES):
    # Trigger measurement on 1553 BC command word
    wait_for_trigger(source='PFI0', edge='RISING')

    # Measure response time (BC→RT)
    response_time_us = read_counter(channel=0) * 1e6  # convert to μs

    # Measure word gap
    word_gap_us = read_counter(channel=1) * 1e6

    results.append({
        'sample': i,
        'response_time_us': response_time_us,
        'word_gap_us': word_gap_us
    })

# Statistical analysis
import numpy as np
rt_values = [r['response_time_us'] for r in results]
print(f"Response time: mean={np.mean(rt_values):.3f}μs, "
      f"std={np.std(rt_values):.3f}μs, "
      f"min={np.min(rt_values):.3f}μs, max={np.max(rt_values):.3f}μs")

Pass/Fail Evaluation

def evaluate_milstd1553_timing(results):
    # MIL-STD-1553 specification limits
    SPEC = {
        'response_time_us': (4.0, 12.0),   # min, max in μs
        'word_gap_us': (2.0, float('inf')), # min only
        'message_gap_us': (4.0, float('inf'))
    }

    failures = []
    for r in results:
        for param, (min_val, max_val) in SPEC.items():
            if param in r:
                val = r[param]
                if val < min_val or val > max_val:
                    failures.append({
                        'sample': r['sample'],
                        'parameter': param,
                        'measured': val,
                        'limit': f"{min_val}–{max_val} μs"
                    })

    return {
        'pass': len(failures) == 0,
        'total_samples': len(results),
        'failures': failures
    }

Generating Traceable Reports

import json
from datetime import datetime

def generate_test_report(dut_serial, results, evaluation):
    report = {
        'report_type': 'MIL-STD-1553 Timing Verification',
        'dut_serial': dut_serial,
        'test_date': datetime.utcnow().isoformat(),
        'standard': 'MIL-STD-1553B',
        'equipment': 'Neometrix PC-Based Counter Timer Test Rig',
        'summary': evaluation,
        'statistics': {
            'response_time_us': {
                'mean': np.mean([r['response_time_us'] for r in results]),
                'std': np.std([r['response_time_us'] for r in results]),
                'min': np.min([r['response_time_us'] for r in results]),
                'max': np.max([r['response_time_us'] for r in results])
            }
        }
    }
    return json.dumps(report, indent=2)