/usr/lib/python2.7/dist-packages/pyvisa/ctwrapper/highlevel.py is in python-pyvisa 1.8-2.
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"""
pyvisa.ctwrapper.highlevel
~~~~~~~~~~~~~~~~~~~~~~~~~~
Highlevel wrapper of the VISA Library.
This file is part of PyVISA.
:copyright: 2014 by PyVISA Authors, see AUTHORS for more details.
:license: MIT, see LICENSE for more details.
"""
from __future__ import division, unicode_literals, print_function, absolute_import
import logging
import warnings
from pyvisa import constants, errors, highlevel, logger
from pyvisa.compat import integer_types, OrderedDict
from .cthelper import Library, find_library
from . import functions
logger = logging.LoggerAdapter(logger, {'backend': 'ni'})
def add_visa_methods(aclass):
for method in functions.visa_functions:
setattr(aclass, method, getattr(functions, method))
return aclass
def _args_to_str(args):
out = []
for arg in args:
try:
# noinspection PyProtectedMember
out.append(str(arg._obj))
except AttributeError:
out.append(arg)
return tuple(out)
@add_visa_methods
class NIVisaLibrary(highlevel.VisaLibraryBase):
"""High level NI-VISA Library wrapper using ctypes.
The easiest way to instantiate the library is to let `pyvisa` find the
right one for you. This looks first in your configuration file (~/.pyvisarc).
If it fails, it uses `ctypes.util.find_library` to try to locate a library
in a way similar to what the compiler does:
>>> visa_library = NIVisaLibrary()
But you can also specify the path:
>>> visa_library = NIVisaLibrary('/my/path/visa.so')
:param library_path: path of the VISA library.
"""
@staticmethod
def get_library_paths():
"""Return a tuple of possible library paths.
:rtype: tuple
"""
from ..util import LibraryPath, read_user_library_path
user_lib = read_user_library_path()
tmp = [find_library(library_path)
for library_path in ('visa', 'visa32', 'visa32.dll')]
tmp = [LibraryPath(library_path)
for library_path in tmp
if library_path is not None]
logger.debug('Automatically found library files: %s' % tmp)
if user_lib:
user_lib = LibraryPath(user_lib, 'user')
try:
tmp.remove(user_lib)
except ValueError:
pass
tmp.insert(0, user_lib)
return tuple(tmp)
@staticmethod
def get_debug_info():
"""Return a list of lines with backend info.
"""
from pyvisa import __version__
d = OrderedDict()
d['Version'] = '%s (bundled with PyVISA)' % __version__
paths = NIVisaLibrary.get_library_paths()
for ndx, visalib in enumerate(paths, 1):
nfo = OrderedDict()
nfo['found by'] = visalib.found_by
nfo['bitness'] = visalib.bitness
try:
lib = NIVisaLibrary(visalib)
sess, _ = lib.open_default_resource_manager()
nfo['Vendor'] = str(lib.get_attribute(sess, constants.VI_ATTR_RSRC_MANF_NAME)[0])
nfo['Impl. Version'] = str(lib.get_attribute(sess, constants.VI_ATTR_RSRC_IMPL_VERSION)[0])
nfo['Spec. Version'] = str(lib.get_attribute(sess, constants.VI_ATTR_RSRC_SPEC_VERSION)[0])
lib.close(sess)
except Exception as e:
e = str(e)
if 'No matching architecture' in e:
nfo['Could not get more info'] = 'Interpreter and library have different bitness.'
else:
nfo['Could not get more info'] = str(e).split('\n')
d['#%d: %s' % (ndx, visalib)] = nfo
if not paths:
d['Binary library'] = 'Not found'
return d
def _init(self):
try:
lib = Library(self.library_path)
except OSError as exc:
raise errors.LibraryError.from_exception(exc, self.library_path)
self.lib = lib
# Set the argtypes, restype and errcheck for each function
# of the visa library. Additionally store in `_functions` the
# name of the functions.
functions.set_signatures(self.lib, errcheck=self._return_handler)
logger.debug('Library signatures: %d ok, %d failed',
len(getattr(self.lib, '_functions', [])),
len(getattr(self.lib, '_functions_failed', [])))
# Set the library functions as attributes of the object.
for method_name in getattr(self.lib, '_functions', []):
setattr(self, method_name, getattr(self.lib, method_name))
def _return_handler(self, ret_value, func, arguments):
"""Check return values for errors and warnings.
"""
logger.debug('%s%s -> %r',
func.__name__, _args_to_str(arguments), ret_value,
extra=self._logging_extra)
try:
ret_value = constants.StatusCode(ret_value)
except ValueError:
pass
self._last_status = ret_value
# The first argument of almost all registered visa functions is a session.
# We store the error code per session
session = None
if func.__name__ not in ('viFindNext', ):
try:
session = arguments[0]
except KeyError:
raise Exception('Function %r does not seem to be a valid '
'visa function (len args %d)' % (func, len(arguments)))
# Functions that use the first parameter to get a session value.
if func.__name__ in ('viOpenDefaultRM', ):
# noinspection PyProtectedMember
session = session._obj.value
if isinstance(session, integer_types):
self._last_status_in_session[session] = ret_value
else:
# Functions that might or might have a session in the first argument.
if func.__name__ not in ('viClose', 'viGetAttribute', 'viSetAttribute', 'viStatusDesc'):
raise Exception('Function %r does not seem to be a valid '
'visa function (type args[0] %r)' % (func, type(session)))
if ret_value < 0:
raise errors.VisaIOError(ret_value)
if ret_value in self.issue_warning_on:
if session and ret_value not in self._ignore_warning_in_session[session]:
warnings.warn(errors.VisaIOWarning(ret_value), stacklevel=2)
return ret_value
def list_resources(self, session, query='?*::INSTR'):
"""Returns a tuple of all connected devices matching query.
:param query: regular expression used to match devices.
"""
resources = []
try:
find_list, return_counter, instrument_description, err = self.find_resources(session, query)
except errors.VisaIOError as e:
if e.error_code == constants.StatusCode.error_resource_not_found:
return tuple()
raise e
resources.append(instrument_description)
for i in range(return_counter - 1):
resources.append(self.find_next(find_list)[0])
self.close(find_list)
return tuple(resource for resource in resources)
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