/usr/lib/python2.7/dist-packages/pyvisa-py/gpib.py is in python-pyvisa-py 0.2-2.
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"""
pyvisa-py.gpib
~~~~~~~~~~~~~~
GPIB Session implementation using linux-gpib.
:copyright: 2015 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 bisect import bisect
from pyvisa import constants, logger
from .sessions import Session, UnknownAttribute
try:
import gpib
from Gpib import Gpib
except ImportError as e:
Session.register_unavailable(constants.InterfaceType.gpib, 'INSTR',
'Please install linux-gpib to use this resource type.\n%s' % e)
raise
def _find_listeners():
"""Find GPIB listeners.
"""
for i in range(31):
if gpib.listener(BOARD, i) and gpib.ask(BOARD, 1) != i:
yield i
StatusCode = constants.StatusCode
SUCCESS = StatusCode.success
# linux-gpib timeout constants, in milliseconds. See self.timeout.
TIMETABLE = (0, 1e-2, 3e-2, 1e-1, 3e-1, 1e0, 3e0, 1e1, 3e1, 1e2, 3e2, 1e3, 3e3,
1e4, 3e4, 1e5, 3e5, 1e6)
# TODO: Check board indices other than 0.
BOARD = 0
# TODO: Check secondary addresses.
@Session.register(constants.InterfaceType.gpib, 'INSTR')
class GPIBSession(Session):
"""A GPIB Session that uses linux-gpib to do the low level communication.
"""
@staticmethod
def list_resources():
return ['GPIB0::%d::INSTR' % pad for pad in _find_listeners()]
def after_parsing(self):
minor = self.parsed.board
pad = self.parsed.primary_address
self.handle = gpib.dev(int(minor), int(pad))
self.interface = Gpib(self.handle)
@property
def timeout(self):
# 0x3 is the hexadecimal reference to the IbaTMO (timeout) configuration
# option in linux-gpib.
return TIMETABLE[self.interface.ask(3)]
@timeout.setter
def timeout(self, value):
"""
linux-gpib only supports 18 discrete timeout values. If a timeout
value other than these is requested, it will be rounded up to the closest
available value. Values greater than the largest available timout value
will instead be rounded down. The available timeout values are:
0 Never timeout.
1 10 microseconds
2 30 microseconds
3 100 microseconds
4 300 microseconds
5 1 millisecond
6 3 milliseconds
7 10 milliseconds
8 30 milliseconds
9 100 milliseconds
10 300 milliseconds
11 1 second
12 3 seconds
13 10 seconds
14 30 seconds
15 100 seconds
16 300 seconds
17 1000 seconds
"""
self.interface.timeout(bisect(TIMETABLE, value))
def close(self):
gpib.close(self.handle)
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, constants.StatusCode
"""
# 0x2000 = 8192 = END
checker = lambda current: self.interface.ibsta() & 8192
reader = lambda: self.interface.read(1)
return self._read(reader, count, checker, False, None, False, gpib.GpibError)
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
"""
logger.debug('GPIB.write %r' % data)
try:
self.interface.write(data)
return SUCCESS
except gpib.GpibError:
# 0x4000 = 16384 = TIMO
if self.interface.ibsta() & 16384:
return 0, StatusCode.error_timeout
else:
return 0, StatusCode.error_system_error
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)
"""
if attribute == constants.VI_ATTR_GPIB_READDR_EN:
# IbaREADDR 0x6
# Setting has no effect in linux-gpib.
return self.interface.ask(6), SUCCESS
elif attribute == constants.VI_ATTR_GPIB_PRIMARY_ADDR:
# IbaPAD 0x1
return self.interface.ask(1), SUCCESS
elif attribute == constants.VI_ATTR_GPIB_SECONDARY_ADDR:
# IbaSAD 0x2
# Remove 0x60 because National Instruments.
sad = self.interface.ask(2)
if self.interface.ask(2):
return self.interface.ask(2) - 96, SUCCESS
else:
return constants.VI_NO_SEC_ADDR, SUCCESS
elif attribute == constants.VI_ATTR_GPIB_REN_STATE:
# I have no idea how to implement this.
raise NotImplementedError
elif attribute == constants.VI_ATTR_GPIB_UNADDR_EN:
# IbaUnAddr 0x1b
if self.interface.ask(27):
return constants.VI_TRUE, SUCCESS
else:
return constants.VI_FALSE, SUCCESS
elif attribute == constants.VI_ATTR_SEND_END_EN:
# IbaEndBitIsNormal 0x1a
if self.interface.ask(26):
return constants.VI_TRUE, SUCCESS
else:
return constants.VI_FALSE, SUCCESS
elif attribute == constants.VI_ATTR_INTF_NUM:
# IbaBNA 0x200
return self.interface.ask(512), SUCCESS
elif attribute == constants.VI_ATTR_INTF_TYPE:
return constants.InterfaceType.gpib, SUCCESS
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
"""
if attribute == constants.VI_ATTR_GPIB_READDR_EN:
# IbcREADDR 0x6
# Setting has no effect in linux-gpib.
if isinstance(attribute_state, int):
self.interface.config(6, attribute_state)
return SUCCESS
else:
return StatusCode.error_nonsupported_attribute_state
elif attribute == constants.VI_ATTR_GPIB_PRIMARY_ADDR:
# IbcPAD 0x1
if isinstance(attribute_state, int) and 0 <= attribute_state <= 30:
self.interface.config(1, attribute_state)
return SUCCESS
else:
return StatusCode.error_nonsupported_attribute_state
elif attribute == constants.VI_ATTR_GPIB_SECONDARY_ADDR:
# IbcSAD 0x2
# Add 0x60 because National Instruments.
if isinstance(attribute_state, int) and 0 <= attribute_state <= 30:
if self.interface.ask(2):
self.interface.config(2, attribute_state + 96)
return SUCCESS
else:
return StatusCode.error_nonsupported_attribute
else:
return StatusCode.error_nonsupported_attribute_state
elif attribute == constants.VI_ATTR_GPIB_UNADDR_EN:
# IbcUnAddr 0x1b
try:
self.interface.config(27, attribute_state)
return SUCCESS
except gpib.GpibError:
return StatusCode.error_nonsupported_attribute_state
elif attribute == constants.VI_ATTR_SEND_END_EN:
# IbcEndBitIsNormal 0x1a
if isinstance(attribute_state, int):
self.interface.config(26, attribute_state)
return SUCCESS
else:
return StatusCode.error_nonsupported_attribute_state
raise UnknownAttribute(attribute)
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