Not able to query instrument using PyVISA

Question

I am trying to control Rohde & Schwarz signal generator using PyVISA

PyVISA details is as follows.

C:\Python27\lib\site-packages\pyvisa\ctwrapper\functions.py:1222: VisaIOWarning: VI_WARN_CONFIG_NLOADED (1073676407): The specified configuration either does not exist or could not be loaded. VISA-specified defaults will be used.
 ret = library.viOpenDefaultRM(byref(session))
Machine Details:
 Platform ID: Windows-8-6.2.9200
 Processor: Intel64 Family 6 Model 61 Stepping 4, GenuineIntel
Python:
 Implementation: CPython
 Executable: C:\Python27\python.exe
 Version: 2.7.9
 Compiler: MSC v.1500 32 bit (Intel)
 Bits: 32bit
 Build: Dec 10 2014 12:24:55 (#default)
 Unicode: UCS2
PyVISA Version: 1.7
Backends:
 ni:
 Version: 1.7 (bundled with PyVISA)
 #1: C:\Windows\system32\visa32.dll:
 found by: auto
 bitness: 32
 Vendor: National Instruments
 Impl. Version: 5243905
 Spec. Version: 5243136
 #2: C:\Windows\system32\visa32.dll:
 found by: auto
 bitness: 32
 Vendor: National Instruments
 Impl. Version: 5243905
 Spec. Version: 5243136

NI-VISA version is 5.4.1. Here is what I get when I run following code

>>> import visa
>>> rm = visa.ResourceManager()
C:\Python27\lib\site-packages\pyvisa\ctwrapper\functions.py:1222: VisaIOWarning: VI_WARN_CONFIG_NLOADED (1073676407): The specified configuration either does not exist or could not be loaded. VISA-specified defaults will be used.
 ret = library.viOpenDefaultRM(byref(session))
>>> RAS = rm.open_resource('TCPIP::10.8.9.16::5025::SOCKET')
>>> RAS.ask("*idn?")
Traceback (most recent call last):
 File "<stdin>", line 1, in <module>
 File "C:\Python27\lib\site-packages\pyvisa\resources\messagebased.py", line 387, in query
 return self.read()
 File "C:\Python27\lib\site-packages\pyvisa\resources\messagebased.py", line 312, in read
 message = self.read_raw().decode(enco)
 File "C:\Python27\lib\site-packages\pyvisa\resources\messagebased.py", line 286, in read_raw
 chunk, status = self.visalib.read(self.session, size)
 File "C:\Python27\lib\site-packages\pyvisa\ctwrapper\functions.py", line 1582, in read
 ret = library.viRead(session, buffer, count, byref(return_count))
 File "C:\Python27\lib\site-packages\pyvisa\ctwrapper\highlevel.py", line 188, in _return_handler
 raise errors.VisaIOError(ret_value)
pyvisa.errors.VisaIOError: VI_ERROR_TMO (-1073807339): Timeout expired before operation completed.
>>>

Does anyone know what am I doing wrong?

Answer 1

I figured it out. instead of doing

RAS = rm.open_resource('TCPIP::10.8.9.16::5025::SOCKET')

I just had to do

RAS = rm.open_resource('TCPIP::10.8.9.16::inst0::INSTR')

or

RAS = rm.open_resource('TCPIP::10.8.9.16::INSTR')

either works

Answer 2

 import visa
 import socket
 try:
 #open connection
 rm = visa.ResourceManager()
 c = (rm.list_resources())
 myinst = rm.open_resource('TCPIP::xxx.xxx.xxx.xxx::inst0::INSTR')
 #Close Connection
 myinst.close()
 print 'close instrument connection'
 except Exception as err:
 print 'Exception: ' + str(err.message)
 finally:
 #perform clean up operations
 print 'complete'