/usr/lib/python3/dist-packages/pyvisa-py/usb.py is in python3-pyvisa-py 0.2-2.
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"""
pyvisa-py.usb
~~~~~~~~~~~~~
Serial Session implementation using PyUSB.
:copyright: 2014 by PyVISA-py Authors, see AUTHORS for more details.
:license: MIT, see LICENSE for more details.
"""
from __future__ import division, unicode_literals, print_function, absolute_import
from pyvisa import constants, attributes
from .sessions import Session, UnknownAttribute
try:
import usb
from .protocols import usbtmc, usbutil, usbraw
except ImportError as e:
Session.register_unavailable(constants.InterfaceType.usb, 'INSTR',
'Please install PyUSB to use this resource type.\n%s' % e)
Session.register_unavailable(constants.InterfaceType.usb, 'RAW',
'Please install PyUSB to use this resource type.\n%s' % e)
raise
try:
_ = usb.core.find()
except ValueError as e:
msg = 'PyUSB does not seem to be properly installed.\n' \
'Please refer to PyUSB documentation and ' \
'install a suitable backend like ' \
'libusb 0.1, libusb 1.0, libusbx, ' \
'libusb-win32 or OpenUSB\%s' % e
Session.register_unavailable(constants.InterfaceType.usb, 'INSTR', msg)
Session.register_unavailable(constants.InterfaceType.usb, 'RAW', msg)
raise
from . import common
StatusCode = constants.StatusCode
SUCCESS = StatusCode.success
class USBSession(Session):
"""Base class for drivers that communicate with usb devices
via usb port using pyUSB
"""
timeout = 2000
@staticmethod
def list_resources():
"""Return list of resources for this type of USB device"""
raise NotImplementedError
@classmethod
def get_low_level_info(cls):
try:
ver = usb.__version__
except AttributeError:
ver = 'N/A'
try:
# noinspection PyProtectedMember
backend = usb.core.find()._ctx.backend.__class__.__module__.split('.')[-1]
except:
backend = 'N/A'
return 'via PyUSB (%s). Backend: %s' % (ver, backend)
def read(self, count):
"""Reads data from device or interface synchronously.
Corresponds to viRead function of the VISA library.
:param count: Number of bytes to be read.
:return: data read, return value of the library call.
:rtype: (bytes, VISAStatus)
"""
supress_end_en, _ = self.get_attribute(constants.VI_ATTR_SUPPRESS_END_EN)
if supress_end_en:
raise ValueError('VI_ATTR_SUPPRESS_END_EN == True is currently unsupported by pyvisa-py')
term_char, _ = self.get_attribute(constants.VI_ATTR_TERMCHAR)
term_char_en, _ = self.get_attribute(constants.VI_ATTR_TERMCHAR_EN)
return self._read(lambda: self.interface.read(1),
count,
lambda current: False,
supress_end_en,
term_char,
term_char_en,
usb.USBError)
def write(self, data):
"""Writes data to device or interface synchronously.
Corresponds to viWrite function of the VISA library.
:param data: data to be written.
:type data: bytes
:return: Number of bytes actually transferred, return value of the library call.
:rtype: (int, VISAStatus)
"""
send_end, _ = self.get_attribute(constants.VI_ATTR_SEND_END_EN)
count = self.interface.write(data)
return count, SUCCESS
def close(self):
self.interface.close()
def _get_attribute(self, attribute):
"""Get the value for a given VISA attribute for this session.
Use to implement custom logic for attributes.
:param attribute: Resource attribute for which the state query is made
:return: The state of the queried attribute for a specified resource, return value of the library call.
:rtype: (unicode | str | list | int, VISAStatus)
"""
raise UnknownAttribute(attribute)
def _set_attribute(self, attribute, attribute_state):
"""Sets the state of an attribute.
Corresponds to viSetAttribute function of the VISA library.
:param attribute: Attribute for which the state is to be modified. (Attributes.*)
:param attribute_state: The state of the attribute to be set for the specified object.
:return: return value of the library call.
:rtype: VISAStatus
"""
raise UnknownAttribute(attribute)
@Session.register(constants.InterfaceType.usb, 'INSTR')
class USBInstrSession(USBSession):
"""Base class for drivers that communicate with instruments
via usb port using pyUSB
"""
@staticmethod
def list_resources():
out = []
fmt = 'USB%(board)s::%(manufacturer_id)s::%(model_code)s::' \
'%(serial_number)s::%(usb_interface_number)s::INSTR'
for dev in usbtmc.find_tmc_devices():
intfc = usbutil.find_interfaces(dev, bInterfaceClass=0xfe, bInterfaceSubClass=3)
try:
intfc = intfc[0].index
except (IndexError, AttributeError):
intfc = 0
out.append(fmt % dict(board=0,
manufacturer_id=dev.idVendor,
model_code=dev.idProduct,
serial_number=dev.serial_number,
usb_interface_number=intfc))
return out
def after_parsing(self):
self.interface = usbtmc.USBTMC(int(self.parsed.manufacturer_id, 0),
int(self.parsed.model_code, 0),
self.parsed.serial_number)
for name in 'SEND_END_EN,TERMCHAR,TERMCHAR_EN'.split(','):
attribute = getattr(constants, 'VI_ATTR_' + name)
self.attrs[attribute] = attributes.AttributesByID[attribute].default
@Session.register(constants.InterfaceType.usb, 'RAW')
class USBRawSession(USBSession):
"""Base class for drivers that communicate with usb raw devices
via usb port using pyUSB
"""
@staticmethod
def list_resources():
out = []
fmt = 'USB%(board)s::%(manufacturer_id)s::%(model_code)s::' \
'%(serial_number)s::%(usb_interface_number)s::RAW'
for dev in usbraw.find_raw_devices():
intfc = usbutil.find_interfaces(dev, bInterfaceClass=0xFF)
try:
intfc = intfc[0].index
except (IndexError, AttributeError):
intfc = 0
out.append(fmt % dict(board=0,
manufacturer_id=dev.idVendor,
model_code=dev.idProduct,
serial_number=dev.serial_number,
usb_interface_number=intfc))
return out
def after_parsing(self):
self.interface = usbraw.USBRawDevice(int(self.parsed.manufacturer_id, 0),
int(self.parsed.model_code, 0),
self.parsed.serial_number)
for name in 'SEND_END_EN,TERMCHAR,TERMCHAR_EN'.split(','):
attribute = getattr(constants, 'VI_ATTR_' + name)
self.attrs[attribute] = attributes.AttributesByID[attribute].default
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