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pyvisa / pyvisa-py

A pure python PyVISA backend
https://pyvisa-py.readthedocs.io
MIT License
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"list_resources" empty but can still connect explicitly using "open_resource" #257

Open christofferTP opened 8 years ago

christofferTP commented 8 years ago

Python 2.7.9 (default, Dec 10 2014, 12:24:55) [MSC v.1500 32 bit (Intel)] on win32 Type "help", "copyright", "credits" or "license" for more information.

import visa rm = visa.ResourceManager() rm.list_resources() () rm.open_resource('TCPIP0::K-34461A-17982::inst0::INSTR') <'TCPIPInstrument'(u'TCPIP0::K-34461A-17982::inst0::INSTR')>

What gives? Can resources be blocked by other applications, not allowing them to be read by list_resources, or is this an issue on my part? I have drivers and I/O libraries installed for the device im using (KeySight 3446X)

MatthieuDartiailh commented 6 years ago

I have no idea what could have caused that. Will try to look into it.

RognanCr commented 5 years ago

i have exactly the same problem

MatthieuDartiailh commented 5 years ago

Could you post the output of pyvisa-info ? and the model of the instrument you are trying to connect to ?

RognanCr commented 5 years ago

Model of instrument is keithley 34461A. If i use list_resources it will find only ASRLCOM1::INSTR

but when i use explicitly visa.ResourceManager.open_resource("TCPIP0::K-34461A-10709::inst0::INSTR") it works fine. Same story with other instrument Agilent 34461A.

Machine Details: Platform ID: Windows-10-10.0.17763-SP0 Processor: Intel64 Family 6 Model 158 Stepping 9, GenuineIntel

Python: Implementation: CPython Executable: C:\Users\zapadlik\AppData\Local\Programs\Python\Python36-32\python.exe Version: 3.6.1 Compiler: MSC v.1900 32 bit (Intel) Bits: 32bit Build: Mar 21 2017 17:54:52 (#v3.6.1:69c0db5) Unicode: UCS4

PyVISA Version: 1.9.1

Backends: ni: Version: 1.9.1 (bundled with PyVISA) Binary library: Not found py: Version: 0.3.1 ASRL INSTR: Available via PySerial (3.4) USB INSTR: Available via PyUSB (1.0.2). Backend: N/A USB RAW: Available via PyUSB (1.0.2). Backend: N/A TCPIP INSTR: Available TCPIP SOCKET: Available GPIB INSTR: Please install linux-gpib to use this resource type. No module named 'gpib'

MatthieuDartiailh commented 5 years ago

This is a known limitation of the pyvisa-py backend (cf https://github.com/pyvisa/pyvisa-py/issues/165). If you have time to work on a fix, you are welcome.