ni-visa

ni-visa is a Node.js library that allows you to interface with instruments using the NI-VISA standard. It provides an easy-to-use API for managing VISA resources and communicating with instruments. The library expects that RsVisa is installed on your system. Alternatively, you can provide the path to your own dynamic library that supports the NI-VISA standard.

Features

• Resource Management: List and filter VISA resources.
• Instrument Communication: Open an instrument and send queries.
• Graceful Cleanup: Automatically handles closing of instruments and resource managers.
• Customizable: Option to specify a custom dynamic library path.

Requirements

• RsVisa: The library is built to work with RsVisa.
• Custom Dynamic Library: If RsVisa is not used, you can specify a custom path to a dynamic library that supports NI-VISA.
• Node.js 23+: The examples and type stripping support require Node.js version 23 or later.

Installation

Install the library using npm:

npm install ni-visa

Usage

Below is a usage example demonstrating how to list VISA resources, filter for USB resources, open an instrument, query its identity, and then properly close all connections:

import { VisaInstrument, VisaResourceManager } from 'ni-visa';

const rm = new VisaResourceManager();

try {
  console.log('Listing resources...');
  const resources = rm.listResources();
  console.log(`Resources: ${resources}`);

  const usbResources = resources.filter((resource) => resource.startsWith('USB'));
  console.log(`USB resources: ${usbResources}...`);

  const selectedResource = usbResources[0];
  if (!selectedResource) {
    throw new Error('No USB resources found');
  }

  console.log(`Opening instrument: ${selectedResource}...`);
  const instr = rm.open(selectedResource);

  try {
    await onInstrumentOpened(instr);
  } finally {
    console.log('Closing instrument...');
    instr.close();
  }

} catch (error) {
  console.error(error);
} finally {
  console.log('Closing default resource manager...');
  rm.close();
}

async function onInstrumentOpened(instr: VisaInstrument) {
  const response = instr.query('*IDN?');
  console.log(`\nInstrument ID: ${response}\n`);
}

Custom Dynamic Library Path

If you want to use your own dynamic library that supports the NI-VISA standard, you can specify its path when initializing the VisaResourceManager:

const rm = new VisaResourceManager('/path/to/your/library');

Running the Examples

The example above is provided in the examples directory and can be run directly using Node.js 23+ (which supports TypeScript type stripping). Simply navigate to the example directory and run:

npm install
node example.ts

API Reference

VisaResourceManager

• listResources(): string[]
  Lists all available VISA resources.
• open(resource: string): VisaInstrument
  Opens a connection to the specified VISA resource.
• close(): void
  Closes the resource manager and cleans up resources.

VisaInstrument

• write(data: Buffer | string): void
  Writes data to the instrument.
• query(command: string): string
  Sends a query command to the instrument and returns its response.
• queryBinary(command: string, bufferSize = 1024): Buffer
  Sends a query command to the instrument and returns its response as a binary buffer.
• close(): void
  Closes the instrument connection.

Contributing

Contributions are welcome! If you find any issues or have suggestions, please open an issue or submit a pull request on GitHub.

License

This project is licensed under the MIT License.

Support

If you have any questions or need further assistance, please open an issue on the GitHub repository.