PyVisa | Trouble I identifying Resources | Rigol DS1054 | Keithly 2200-20-5

You need to create a udev rule for USBTMC devices.

echo 'SUBSYSTEM=="usb", MODE="0666", GROUP="usbusers"' >> 99-com.rules sudo mv 99-com.rules /etc/udev/rules.d/99-com.rules

Make sure you're in "usbusers" and do a reboot after that. (And really, reboot. I'm not certain what service has to restart to make it work.) pyVISA may be able to see them then.

Also, the license for R&S's VISA driver is not very restrictive. My interpretation is that you can use it with anyone's hardware/software. I also know they use pyVISA quite a bit, so it works really well with pyVISA. There are builds for various linux versions on their site.

Do I need to create the 99-com.rules file. My system had 99-nivisia_usbraw.rules file in the udev directory? Similar but not the same I can try both out until you reply.

Do I need to create the 99-com.rules file. My system had 99-nivisia_usbraw.rules file in the udev directory? Similar but not the same I can try both out until you reply.

I cannot say for sure. The udev rule may only apply when you're using the pyvisa-py VISA driver.

I do not own any NI software or hardware, so I am not able to use NI-VISA (it's against their license to use it unless it is with their tools, even though it is "free.")

I don't have it installed on any of the machines I've used with pyvisa. I either use pyvisa-py, R&S VISA, or Keysight's IO Connect. (But I have only used IO Connect on Windows, not Linux.)

If you have a VISA driver installed, such as NI-VISA, I would use their connection tools to verify what is connected and troubleshoot it. pyvsia's ResouceManager talks to it. For example, if NI-VISA's connection tool does not see the USB instruments, then pyvisa's ResourceManager won't either.

Remember, pyvisa talks to a VISA driver. If you don't have one installed, then it can use its own "pyvisa-py" driver.

Yeah I went down the NI-VISA path because that is where the Keithely ( Tecktonix) site took me.  I can try to uninstall it and use pyvisapy as the backend.  To be clear that pyvisa acts like visa drive giving me the usbtmc backend then I use pyvisa for scripiting?

baldengineer 

Ok so switching to the pyvisapy backend seemed to do the trick. It now shot the usb address as detailed in the manual. Many thanks to everyone in the thread for help. See output belowl.

Python 3.10.10 (main, Mar  5 2023, 22:26:53) [GCC 12.2.1 20230201] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import visa
/usr/lib/python3.10/site-packages/visa.py:13: FutureWarning: The visa module provided by PyVISA is being deprecated. You can replace `import visa` by `import pyvisa as visa` to achieve the same effect.

The reason for the deprecation is the possible conflict with the visa package provided by the https://github.com/visa-sdk/visa-python which can result in hard to debug situations.
  warnings.warn(
>>> import pyvisa as visa
>>> rm =visa.ResourceManager('@py')
>>> rm.list_resources()
('USB0::1510::8704::9201747::0::INSTR',)
>>> 

Oh, right. Keithley/Tek is licensed. I forgot you said you were using one of their PSUs.

pyvisa is a wrapper for the VISA driver. Example VISA drivers are:

1. NI-VISA
2. R&S VISA
3. Keysight IO Connect (or whatever they call it now)
4. pyvisa-py

I know it is confusing because the name is so similar. "pyvisa-py" is a pure Python VISA implementation. "pyvisa" is the wrapper. (also pyvisa-py is not installed automatically if you pip installed pyvisa.)

The pyvisa maintainers specifically write pyvisa to work as a wrapper for NI-VISA. So, if you can use NI-VISA, that is your best option. pyvisa-py is less feature0rich and is only a good option if you have no other VISA driver.

The VISA driver is what talks to the devices via USBTMC or TCPIP or Serial or whatever.

The result is that if NI-VISA's configuration tool cannot see your devices, then pyvisa won't be able to either.

On Linux this may become a stretch, but for Windows, Rigol (and other SCPI compliant manufacturers) supply a VISA runtime with their software install. Usually an OEM-licensed NI-VISA version ...

Yeah, I think you still have to be careful there. Tier 1 manufacturers are generally covered. But some of the smaller (and very popular) companies are not. Some will even link their customers to NI's website, but they don't have a license agreement. They're just banking on the fact that their customer is using LabView.

And, while I am not a lawyer, my read of the NI-VISA runtime license only covers using the manufacturer's "software," not generic SCPI usage.

I know it is splitting hairs. But since NI is so purposefully restrictive, I would rather err on the side of caution.