Using External Hardware Devices.md

Connecting to External Signal Processing Equipment

VISA via USB connection

This is the simplest way to communicate with devices like oscilloscopes, Signal Generators etc Even older devices have a USB connection that uses VISA.

To connect to a device via VISA you need to install the VISA package for the programming language you prefer.

Despite VISA being used over the raw USB connection, you might have trouble with your operating system. For Ubuntu Linux, you need to specifically allow the use of these kind of connection by the users. Otherwise, you might not be able to list your device as VISA resource despite you being able to see it listed in lsusb output.

Ubuntu:

• Modify the following file:

sudo vim /etc/udev/rules.d/99-com.rules

• Add the following lines, save and exit:

SUBSYSTEM=="usb", MODE="0666", GROUP="usbusers"

• reboot your Linux

(Adapted from https://stackoverflow.com/questions/66480203/pyvisa-not-listing-usb-instrument-on-linux/66480539#66480539)

Using Python:

• Dependencies Installation:

  pip install pyvisa-py zeroconf

• Minimal Example:

  import pyvisa
  
  def main():
   _rm = pyvisa.ResourceManager()
   devices = _rm.list_resources()
   print(devices)
  
  if __name__=='__main__':
  main()