Instrument Remote Control (VISA / SCPI)

Overview

How it works

TstoneLab can communicate with your network analyzer over a TCP/IP network. You write a SCPI command sequence that tells the instrument what to measure; TstoneLab runs it, downloads the resulting Touchstone file, and opens it immediately in a QuickChart tab.

This guide covers:

1. Network setup
2. Installing a VISA runtime
3. Connecting to your instrument
4. Writing a SCPI command sequence
5. Running a measurement
6. Tip — using AI to write SCPI commands for your instrument

Step 1

Network setup

Your PC and your instrument must be on the same network.

Using a lab network (typical): If your PC and instrument are on the same lab network (Ethernet switch or Wi-Fi), they should already be reachable. Find the instrument's IP address from its front panel (usually under System → Network or similar).

Using a direct Ethernet cable (point-to-point): With a single cable and no router or switch in between, there is no DHCP server to assign addresses, so you must set a static IP on both sides.

The key rule: both devices must share the same network prefix — the part of the address defined by the subnet mask must be identical. With a mask of 255.255.255.0, the first three octets (192.168.1.___) define the network. Any two devices whose addresses start with 192.168.1. and use this mask are on the same network and can communicate directly. Only the last octet must differ.

Example configuration:

Both addresses share the 192.168.1.x prefix. The PC is .10 and the instrument is .100 — same network.

Verify connectivity. Open a command prompt and ping your instrument:

ping 192.168.1.100

If you get replies, you are ready to connect.

Step 2

Install a VISA runtime

TstoneLab communicates with instruments using the VISA (Virtual Instrument Software Architecture) standard, so you need a VISA runtime installed on your PC. Any of these will work — they are free and interchangeable regardless of your instrument's brand:

After installation, restart your PC. The VISA runtime places visa64.dll in your System32 folder, which TstoneLab uses at runtime.

Step 3

Connecting to your instrument

1. In TstoneLab, click Connect Instrument (from the left panel or the Quick Actions area).
2. Type your instrument's VISA address. The format is:
   VISA address format Copy

   TCPIP::<IP_ADDRESS>::<port>::SOCKET

   or for HiSLIP:
   HiSLIP Copy

   TCPIP::<IP_ADDRESS>::hislip0::INSTR

   Common examples:
   Examples Copy

   TCPIP::192.168.1.100::hislip0::INSTR
   TCPIP::192.168.1.100::5025::SOCKET

3. Click Connect. TstoneLab opens a VISA session, sends *IDN?, and shows your instrument's identification string (manufacturer, model, serial number, firmware version).
4. Once connected, the SCPI Editor tab opens automatically.

Step 4

Writing a SCPI command sequence

TstoneLab provides a step-by-step SCPI editor where you define a measurement sequence. Each step is one of:

A typical sequence has four sections:

1. Setup — Clear existing traces, configure display windows.
2. Define S-parameters — Create trace definitions (S11, S21, S12, S22, etc.).
3. Measure — Set single sweep mode, trigger a measurement, wait for completion.
4. Transfer — Save the Touchstone file on the instrument, then download it to your PC.

Starting points

Built-in presets (verified instruments)

TstoneLab ships with two verified presets you can load as starting points:

Step 5

Running a measurement

1. Use the SCPI Editor to load a preset or build your own.
2. Click Measure. TstoneLab executes each step sequentially and shows progress.
3. When the ReadSnpBinary (or ReadSnpText) step completes, the downloaded Touchstone data is saved to:
   Save location

   Documents\TstoneLab\InstrumentData\

   The filename includes your instrument model and a timestamp, for example N5222A_20260407_143052.s4p.
4. The file shows up under the Instruments node in the Explorer tree.
5. A new QuickChart tab opens immediately with your S-parameter traces.

Pro tip

Use AI to write SCPI commands for your instrument

Writing SCPI from scratch is tedious when your instrument has hundreds of commands. A practical shortcut:

1. Download your instrument's SCPI manual. Search the manufacturer's website for "<your model> SCPI programming guide" — it's usually a PDF.
2. Provide it to an assistant (such as Claude or ChatGPT) along with one of TstoneLab's example presets and a prompt like this:
   Prompt template Copy

   I use a [Your Instrument Brand/Model], a [N]-port Network Analyzer.
   
   Below is a SCPI command sequence for a Keysight PNA (4-port) that works with
   an app called TstoneLab. Please adapt it for my instrument using the attached
   SCPI manual.
   
   The sequence must follow this structure:
   - Setup: Clear existing traces, configure display.
   - Define S-Parameters: Create traces for all S-parameters (S11 through SNN).
   - Measure: Set single sweep mode, trigger, wait for completion.
   - Transfer: Save measurement as a Touchstone (.sNp) file on the instrument,
     then provide the SCPI command to read that file back as a binary block.
   
   [Paste the Keysight PNA or FieldFox preset commands here]
   
   Please output the adapted sequence in the same format (Section / Command / Label).

3. Review and test. The AI may not get everything right on the first try — always verify against your manual.
4. Paste the commands into TstoneLab's SCPI Editor, save as a named sequence, and run it.

If something goes wrong

Troubleshooting

At a glance

Summary