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Experiment: Keysight PNA N5232A Validation

This document summarizes the validation of the Keysight N5232A PNA-L VNA integration into the instrumation HAL.

Setup & Discovery

The N5232A was connected via LAN to the bench network.

Discovery Breakthrough: mDNS & HiSLIP

Standard VISA list_resources() often misses HiSLIP interfaces on complex networks. We enhanced the HAL's AUTO discovery engine with: - mDNS Probing: Proactively resolving a-n5232a-20127.local. - HiSLIP Priority: Specifically checking port 4880 and appending ::hislip0::INSTR. - Address Resolution: Verified that get_instrument("AUTO", "VNA") now correctly identifies the instrument in under 2 seconds.

Validation Script

The following script was used for the final validation. It uses the "AUTO" discovery mode and demonstrates the high-speed 4-trace characterization.

from instrumation.factory import get_instrument

# HAL automatically finds the PNA-L via mDNS/HiSLIP
with get_instrument("AUTO", "VNA") as vna:
    print(f"Connected to: {vna.get_id()}")

    # 1. Optimized Reset
    # PNA-L A.10 requires *RST and explicit OPC fencing
    vna.preset()

    # 2. Robust Catalog Cleanup
    # Must stop sweep (INIT:CONT OFF) before CALC:PAR:DEL:ALL to prevent bus hang
    vna.delete_all_measurements()

    # 3. Multi-Trace/Window Setup
    # Uses 'Display Gating' (DISP:ENAB ON) to bypass firmware SCPI blocks
    params = ["S11", "S21", "S12", "S22"]
    for i, p in enumerate(params):
        vna.create_measurement(f"MEAS_{p}", p, window=i+1, trace=1)

    # 4. Synchronized Data Acquisition
    vna.wait_for_sweep()
    s11_data = vna.get_trace_data("MEAS_S11")

    # 5. High-Speed Binary Screenshot
    # Bypasses fragile MMEM file system; uses HCOP:SDUM:DATA? with 
    # raw binary magic-number detection (\x89PNG)
    img = vna.get_screenshot()
    with open("docs/assets/vna_full_scan.png", "wb") as f:
        f.write(img)

Results

The instrument successfully executed the multi-trace setup. Binary data for all 4 parameters was acquired with 401 points.

Live Multi-Trace Capture (Standard 4-Window Layout)

The screenshot below confirms that the HAL successfully initialized 4 independent windows and traces on the physical hardware.

VNA 4-Window Scan

Troubleshooting & Resolution Summary

  • Display Gating: Older PNA-L (A.10) firmware gates DISP commands when DISP:ENAB is OFF. The driver now handles this transparently.
  • Bus Lockups: Addressed instrument hangs by ensuring the sweep engine is inhibited during measurement deletion.
  • Binary Image Integrity: Solved "corrupted" image issues by switching to read_raw() and manual PNG header detection, bypassing non-standard SCPI block headers on A.10 firmware.
  • Discovery Reliability: Expanded the HAL factory to support HiSLIP and mDNS hostname resolution.

Final Summary

  1. Instrument Found: AUTO mode verified via HiSLIP.
  2. Setup Verified: 4 windows/traces created without SCPI errors.
  3. Data Verified: 401 points of S-parameter data fetched via Little-Endian binary.
  4. Image Verified: Valid PNG captured with correct magic-number header.