Sohum Suthar | Lee Teng @ APS @ Argonne National Laboratory

Initial Setup (PC)

Initially, it is necessary to install the required driver support for the Vector Network Analyzer (VNA). The R&S ZVA-24 can be interfaced using NI-VISA (National Instruments Virtual Instrument Software Architecture) through the NI MAX (Measurement & Automation Explorer) software or similar software such as R&S VISA (link to docs).

Install NI MAX

Download the package from the NI System Configuration webpage or by using NI Package Manager and searching for "NI System Configuration" in the Browse Products tab.
Run the downloaded executable file.
Check the "NI Measurement & Automation Explorer" box and proceed with the installation.
Restart your computer to complete the installation.

Note: NI MAX is included with all NI drivers such as NI-VISA.

For more information on how to correctly install NI VISA, please refer to the documentation provided by National Instruments.

Physical LAN Connection

To connect the ZVA-24 Vector Network Analyzer to your Windows computer via LAN, follow these steps:

Connect a LAN/ethernet cable to one of the LAN ports on the rear panel of the analyzer.

Ensure that the LAN ports of the analyzer are auto-crossover Ethernet ports, which can be connected directly to a computer or another test instrument.

TCP/IP Configuration

The LAN TCP/IP configuration for the analyzer can be obtained in different ways depending on the network capacities.

If the network supports dynamic TCP/IP configuration using DHCP (Dynamic Host Configuration Protocol), the configuration can be assigned automatically.
If the network does not support DHCP or if the analyzer is set to use alternate TCP/IP configuration, the configuration must be entered manually.
By default, the analyzer is configured to use dynamic TCP/IP, so it is safe to establish a physical connection to the LAN without any previous analyzer configuration.

Finding your IP

On your VNA, open the command prompt and run the command:

ipconfig

The output will be similar to the following:

Look for the “Ethernet adapter Local Area Connection” IP address.

Note: If your network does not support DHCP or if you choose to disable dynamic TCP/IP configuration, you must enter a valid TCP/IP configuration before connecting the analyzer to the LAN.

Host Configuration

Using NI MAX to Connect the ZVA-24 to the Windows Computer:

Install NI MAX:

Ensure that you have NI MAX (Measurement & Automation Explorer) installed on your computer.

Open NI MAX:

Launch NI MAX from your Start menu

Create a New VISA TCP/IP Resource:

In NI MAX, right-click on "Devices and Interfaces" and select "Create New..."

Choose "VISA TCP/IP Resource" from the list of options.

Manual Entry of LAN Instrument:

Select "Manual entry of LAN Instrument."

Enter the IP address of the ZVA-24 into the field "Hostname or IP Address." Use the IP address obtained from above.

Validate Connection:

Use the "Validate" button to verify that the VISA connection can be successfully established. NI MAX will attempt to communicate with the instrument and confirm the connection.

Open VISA Test Panel:

Once the connection is validated, right-click on the newly created resource under "Devices and Interfaces" and select "Open VISA Test Panel."

Send IDN? Query:

In the VISA Test Panel, go to the "Input/Output" tab.

In the command box, type:

IDN?\n

And click "Query." This command queries the instrument for its identification string.

The instrument should respond with its identification string, confirming that the communication is established.

Verify IP Configuration:

Use the command prompt to verify the network settings by typing ipconfig. This will display the network configuration, including IP address, subnet mask, and gateway, ensuring the ZVA-24 is on the same network.

Ping the Instrument: Use the command prompt to ping the instrument's IP address to ensure it is reachable. Type:

ping <instrument_IP_address>

on the host computer shell and check for a successful reply indicating connectivity.

Before ping:	After ping:

Software Configuration

Reading information using Python:

Install the necessary packages in your Python environment by running the following command in your command prompt or terminal:

python -m pip install -U pyvisa numpy

Install a VISA backend by running the following command in your command prompt or terminal:

python -m pip install -U pyvisa-py

Once the packages are installed, you can import the required module in your Python script and start collecting data. For example:

import numpy as np
import zva as vna

frequencies, measurements, trace_definitions = vna.read_traces( address='TCPIP0::your-instrument-address::inst0::INSTR', num_sweeps=1, channels=[1] )
The read_traces function reads complex-valued trace data from the ZVA-24 VNA. You need to specify the address of the analyzer (e.g., XXXX0::ADDRESS::INSTR') and other parameters such as the number of sweeps and channels.

Python SnP Programming

Exporting Data and Plotting

Data Export: Using the Python script, you can export the trace data from the ZVA-24 into Touchstone files. This is done by running a Python script that reads the complex-valued trace data and saves it into the desired format. Be sure to install scikit before proceeding:

import os
import numpy as np
import skrf as rf
import zva as vna
from RsInstrument.RsInstrument import RsInstrument

vna_address = 'TCPIP0::your-instrument-address::inst0::INSTR'
experiement_name = 'vna_test'

def init_vna(address=vna_address):
    instr = RsInstrument(address, True, False)

    idn = instr.query_str('*IDN?')
    print("****************************************\n")
    print(f"\nHello, I am: '{idn}'")
    print(f'RsInstrument driver version: {instr.driver_version}')
    print(f'Visa manufacturer: {instr.visa_manufacturer}')
    print(f'Instrument full name: {instr.full_instrument_model_name}')
    print(f'Instrument installed options: {",".join(instr.instrument_options)}')
    print("****************************************\n")

def save_touchstone(freqs=None, meas=None, trace_definitions=None, experiement_name=experiement_name):
    num_ports = int(np.sqrt(len(meas[0]) / len(freqs[0])))

    freqs = freqs[0]
    folder_path = os.getcwd()    
    freq = rf.Frequency.from_f(freqs, unit='Hz')
    freq.unit = 'GHz'
    filename = 'snp_files'
    N = len(freq.f)
    os.makedirs(os.path.join(folder_path, filename), exist_ok=True)

    for inx, data in enumerate(meas[0]):
        S_para = np.array([[[s11,s12], [s21,s22]] for s11,s12,s21,s22 in zip(data[0],data[1],data[2],data[3])])

        touchstone_name = filename + f'_{experiement_name}_{inx+1:0{len(str(N))}d}'

        NW = rf.Network(s=S_para, frequency=freq, name = touchstone_name)
        NW.write_touchstone(filename = touchstone_name,
                            dir = os.path.join(folder_path, filename), skrf_comment=False)
        print("saved trace to", os.path.join(folder_path, filename, touchstone_name))

def grab_data(address=vna_address, sweeps=1, channels=[1]):
    frequencies, measurements, trace_definitions = vna.read_traces(address=address, num_sweeps=sweeps, channels=channels)

    return frequencies, measurements, trace_definitions

if __name__ == '__main__':
    init_vna()
    freqs, meas, trace_definitions = grab_data(sweeps=1, channels=[1])
    save_touchstone(freqs, meas, trace_definitions)

Plotting Data: After exporting the data, you can use plotting libraries such as matplotlib in Python to visualize the S-parameter touchstone files:

Additional Resources

Refer to the following resources: