/usr/lib/python3/dist-packages/pyvisa-py/tcpip.py is in python3-pyvisa-py 0.2-2.
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"""
pyvisa-py.tcpip
~~~~~~~~~~~~~~~
TCPIP Session implementation using Python Standard library.
:copyright: 2014 by PyVISA-py Authors, see AUTHORS for more details.
:license: MIT, see LICENSE for more details.
"""
import random
import socket
import select
import time
from pyvisa import constants, attributes
from .sessions import Session, UnknownAttribute
from .protocols import vxi11
from . import common
StatusCode = constants.StatusCode
SUCCESS = StatusCode.success
@Session.register(constants.InterfaceType.tcpip, 'INSTR')
class TCPIPInstrSession(Session):
"""A TCPIP Session that uses the network standard library to do the low level communication
using VXI-11
"""
lock_timeout = 1000
timeout = 1000
client_id = None
link = None
max_recv_size = 1024
@staticmethod
def list_resources():
# TODO: is there a way to get this?
return []
def after_parsing(self):
# TODO: board_number not handled
# TODO: lan_device_name not handled
self.interface = vxi11.CoreClient(self.parsed.host_address)
self.lock_timeout = 10000
self.timeout = 10000
self.client_id = random.getrandbits(31)
(error, link,
abort_port,
max_recv_size) = self.interface.create_link(self.client_id, 0, self.lock_timeout,
self.parsed.lan_device_name)
if error:
raise Exception("error creating link: %d" % error)
self.link = link
self.max_recv_size = min(max_recv_size, 2 ** 30) # 1GB
for name in 'SEND_END_EN,TERMCHAR,TERMCHAR_EN'.split(','):
attribute = getattr(constants, 'VI_ATTR_' + name)
self.attrs[attribute] = attributes.AttributesByID[attribute].default
def close(self):
self.interface.destroy_link(self.link)
self.interface.close()
self.link = None
self.interface = None
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
"""
if count < self.max_recv_size:
chunk_length = count
else:
chunk_length = self.max_recv_size
flags = 0
reason = 0
if self.get_attribute(constants.VI_ATTR_TERMCHAR_EN)[0]:
term_char, _ = self.get_attribute(constants.VI_ATTR_TERMCHAR)
else:
term_char = 0
if term_char:
flags = vxi11.OP_FLAG_TERMCHAR_SET
term_char = str(term_char).encode('utf-8')[0]
read_data = bytearray()
end_reason = vxi11.RX_END | vxi11.RX_CHR
read_fun = self.interface.device_read
status = SUCCESS
while reason & end_reason == 0:
error, reason, data = read_fun(self.link, chunk_length, self.timeout,
self.lock_timeout, flags, term_char)
if error:
return read_data, StatusCode.error_io
read_data.extend(data)
count -= len(data)
if count <= 0:
status = StatusCode.success_max_count_read
break
chunk_length = min(count, chunk_length)
return bytes(read_data), status
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: str
: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)
chunk_size = 1024
try:
if send_end:
flags = vxi11.OP_FLAG_TERMCHAR_SET
else:
flags = 0
num = len(data)
offset = 0
while num > 0:
if num <= chunk_size:
flags |= vxi11.OP_FLAG_END
block = data[offset:offset+self.max_recv_size]
error, size = self.interface.device_write(self.link, self.timeout,
self.lock_timeout, flags, block)
if error:
return offset, StatusCode.error_io
elif size < len(block):
return offset, StatusCode.error_io
offset += size
num -= size
return offset, SUCCESS
except vxi11.Vxi11Error:
return 0, StatusCode.error_timeout
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_TCPIP_ADDR:
return self.host_address, SUCCESS
elif attribute == constants.VI_ATTR_TCPIP_DEVICE_NAME:
raise NotImplementedError
elif attribute == constants.VI_ATTR_TCPIP_HOSTNAME:
raise NotImplementedError
elif attribute == constants.VI_ATTR_TCPIP_KEEPALIVE:
raise NotImplementedError
elif attribute == constants.VI_ATTR_TCPIP_NODELAY:
raise NotImplementedError
elif attribute == constants.VI_ATTR_TCPIP_PORT:
raise NotImplementedError
elif attribute == constants.VI_ATTR_SUPPRESS_END_EN:
raise NotImplementedError
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)
def assert_trigger(self, protocol):
"""Asserts software or hardware trigger.
Corresponds to viAssertTrigger function of the VISA library.
:param protocol: Trigger protocol to use during assertion. (Constants.PROT*)
:return: return value of the library call.
:rtype: VISAStatus
"""
flags = 0
error = self.interface.device_trigger(self.link, flags, self.lock_timeout, self.io_timeout)
if error:
# TODO: Which status to return
raise Exception("error triggering: %d" % error)
return SUCCESS
def clear(self):
"""Clears a device.
Corresponds to viClear function of the VISA library.
:return: return value of the library call.
:rtype: VISAStatus
"""
flags = 0
error = self.interface.device_clear(self.link, flags, self.lock_timeout, self.io_timeout)
if error:
# TODO: Which status to return
raise Exception("error clearing: %d" % error)
def read_stb(self):
"""Reads a status byte of the service request.
Corresponds to viReadSTB function of the VISA library.
:return: Service request status byte, return value of the library call.
:rtype: int, VISAStatus
"""
flags = 0
error, stb = self.interface.device_read_stb(self.link, flags, self.lock_timeout, self.io_timeout)
if error:
# TODO: Which status to return
raise Exception("error reading status: %d" % error)
return stb, SUCCESS
def lock(self, lock_type, timeout, requested_key=None):
"""Establishes an access mode to the specified resources.
Corresponds to viLock function of the VISA library.
:param lock_type: Specifies the type of lock requested, either Constants.EXCLUSIVE_LOCK or Constants.SHARED_LOCK.
:param timeout: Absolute time period (in milliseconds) that a resource waits to get unlocked by the
locking session before returning an error.
:param requested_key: This parameter is not used and should be set to VI_NULL when lockType is VI_EXCLUSIVE_LOCK.
:return: access_key that can then be passed to other sessions to share the lock, return value of the library call.
:rtype: str, VISAStatus
"""
# TODO: lock type not implemented
flags = 0
error = self.interface.device_lock(self.link, flags, self.lock_timeout)
if error:
# TODO: Which status to return
raise Exception("error locking: %d" % error)
def unlock(self):
"""Relinquishes a lock for the specified resource.
Corresponds to viUnlock function of the VISA library.
:return: return value of the library call.
:rtype: VISAStatus
"""
flags = 0
error = self.interface.device_unlock(self.link)
if error:
# TODO: Which message to return
raise Exception("error unlocking: %d" % error)
@Session.register(constants.InterfaceType.tcpip, 'SOCKET')
class TCPIPSocketSession(Session):
"""A TCPIP Session that uses the network standard library to do the low level communication.
"""
lock_timeout = 1000
timeout = 1000
max_recv_size = 4096
# This buffer is used to store the bytes that appeared after termination char
_pending_buffer = b''
@staticmethod
def list_resources():
# TODO: is there a way to get this?
return []
def after_parsing(self):
# TODO: board_number not handled
self.interface = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
self.interface.setblocking(0)
try:
self.interface.connect_ex((self.parsed.host_address, int(self.parsed.port)))
except Exception as e:
raise Exception("could not create socket: %s" % e)
self.attrs[constants.VI_ATTR_TCPIP_ADDR] = self.parsed.host_address
self.attrs[constants.VI_ATTR_TCPIP_PORT] = self.parsed.port
self.attrs[constants.VI_ATTR_INTF_NUM] = self.parsed.board
for name in 'TERMCHAR,TERMCHAR_EN'.split(','):
attribute = getattr(constants, 'VI_ATTR_' + name)
self.attrs[attribute] = attributes.AttributesByID[attribute].default
def close(self):
self.interface.close()
self.interface = None
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
"""
if count < self.max_recv_size:
chunk_length = count
else:
chunk_length = self.max_recv_size
end_char, _ = self.get_attribute(constants.VI_ATTR_TERMCHAR)
enabled, _ = self.get_attribute(constants.VI_ATTR_TERMCHAR_EN)
timeout, _ = self.get_attribute(constants.VI_ATTR_TMO_VALUE)
timeout /= 1000
end_byte = common.int_to_byte(end_char) if end_char else b''
read_fun = self.interface.recv
now = start = time.time()
out = self._pending_buffer
if enabled and end_byte in out:
parts = out.split(end_byte)
self._pending_buffer = b''.join(parts[1:])
return (out + parts[0] + end_byte,
constants.StatusCode.success_termination_character_read)
while now - start <= timeout:
# use select to wait for read ready
select.select([self.interface], [], [])
last = read_fun(chunk_length)
if not last:
time.sleep(.01)
now = time.time()
continue
if enabled and end_byte in last:
parts = last.split(end_byte)
self._pending_buffer = b''.join(parts[1:])
return (out + parts[0] + end_byte,
constants.StatusCode.success_termination_character_read)
out += last
if len(out) == count:
return out, constants.StatusCode.success_max_count_read
else:
return out, constants.StatusCode.error_timeout
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: str
:return: Number of bytes actually transferred, return value of the library call.
:rtype: int, VISAStatus
"""
chunk_size = 4096
num = sz = len(data)
offset = 0
while num > 0:
block = data[offset:min(offset+chunk_size, sz)]
try:
# use select to wait for write ready
select.select([], [self.interface], [])
size = self.interface.send(block)
except socket.timeout as e:
return offset, StatusCode.error_io
if size < len(block):
return offset, StatusCode.error_io
offset += size
num -= size
return offset, SUCCESS
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_TCPIP_HOSTNAME:
raise NotImplementedError
elif attribute == constants.VI_ATTR_TCPIP_KEEPALIVE:
raise NotImplementedError
elif attribute == constants.VI_ATTR_TCPIP_NODELAY:
raise NotImplementedError
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)
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