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# coding: utf-8
"""
This wrapper is for windows or direct access via CANAL API.
Socket CAN is recommended under Unix/Linux systems.
"""
from __future__ import division, print_function, absolute_import
from ctypes import *
from struct import *
import logging
import can
log = logging.getLogger('can.usb2can')
# type definitions
flags = c_ulong
pConfigureStr = c_char_p
handle = c_long
timeout = c_ulong
filter_t = c_ulong
# flags mappings
IS_ERROR_FRAME = 4
IS_REMOTE_FRAME = 2
IS_ID_TYPE = 1
CANAL_ERROR_SUCCESS = 0
CANAL_ERROR_RCV_EMPTY = 19
CANAL_ERROR_TIMEOUT = 32
class CanalStatistics(Structure):
_fields_ = [('ReceiveFrams', c_ulong),
('TransmistFrams', c_ulong),
('ReceiveData', c_ulong),
('TransmitData', c_ulong),
('Overruns', c_ulong),
('BusWarnings', c_ulong),
('BusOff', c_ulong)]
stat = CanalStatistics
class CanalStatus(Structure):
_fields_ = [('channel_status', c_ulong),
('lasterrorcode', c_ulong),
('lasterrorsubcode', c_ulong),
('lasterrorstr', c_byte * 80)]
# data type for the CAN Message
class CanalMsg(Structure):
_fields_ = [('flags', c_ulong),
('obid', c_ulong),
('id', c_ulong),
('sizeData', c_ubyte),
('data', c_ubyte * 8),
('timestamp', c_ulong)]
class Usb2CanAbstractionLayer:
"""A low level wrapper around the usb2can library.
Documentation: http://www.8devices.com/media/products/usb2can/downloads/CANAL_API.pdf
"""
def __init__(self, dll="usb2can.dll"):
"""
:type dll: str or path-like
:param dll (optional): the path to the usb2can DLL to load
:raises OSError: if the DLL could not be loaded
"""
self.__m_dllBasic = windll.LoadLibrary(dll)
if self.__m_dllBasic is None:
log.warning('DLL failed to load at path: {}'.format(dll))
def open(self, configuration, flags):
"""
Opens a CAN connection using `CanalOpen()`.
:param str configuration: the configuration: "device_id; baudrate"
:param int flags: the flags to be set
:raises can.CanError: if any error occurred
:returns: Valid handle for CANAL API functions on success
"""
try:
# we need to convert this into bytes, since the underlying DLL cannot
# handle non-ASCII configuration strings
config_ascii = configuration.encode('ascii', 'ignore')
result = self.__m_dllBasic.CanalOpen(config_ascii, flags)
except Exception as ex:
# catch any errors thrown by this call and re-raise
raise can.CanError('CanalOpen() failed, configuration: "{}", error: {}'
.format(configuration, ex))
else:
# any greater-than-zero return value indicates a success
# (see https://grodansparadis.gitbooks.io/the-vscp-daemon/canal_interface_specification.html)
# raise an error if the return code is <= 0
if result <= 0:
raise can.CanError('CanalOpen() failed, configuration: "{}", return code: {}'
.format(configuration, result))
else:
return result
def close(self, handle):
try:
res = self.__m_dllBasic.CanalClose(handle)
return res
except:
log.warning('Failed to close')
raise
def send(self, handle, msg):
try:
res = self.__m_dllBasic.CanalSend(handle, msg)
return res
except:
log.warning('Sending error')
raise can.CanError("Failed to transmit frame")
def receive(self, handle, msg):
try:
res = self.__m_dllBasic.CanalReceive(handle, msg)
return res
except:
log.warning('Receive error')
raise
def blocking_send(self, handle, msg, timeout):
try:
res = self.__m_dllBasic.CanalBlockingSend(handle, msg, timeout)
return res
except:
log.warning('Blocking send error')
raise
def blocking_receive(self, handle, msg, timeout):
try:
res = self.__m_dllBasic.CanalBlockingReceive(handle, msg, timeout)
return res
except:
log.warning('Blocking Receive Failed')
raise
def get_status(self, handle, CanalStatus):
try:
res = self.__m_dllBasic.CanalGetStatus(handle, CanalStatus)
return res
except:
log.warning('Get status failed')
raise
def get_statistics(self, handle, CanalStatistics):
try:
res = self.__m_dllBasic.CanalGetStatistics(handle, CanalStatistics)
return res
except:
log.warning('Get Statistics failed')
raise
def get_version(self):
try:
res = self.__m_dllBasic.CanalGetVersion()
return res
except:
log.warning('Failed to get version info')
raise
def get_library_version(self):
try:
res = self.__m_dllBasic.CanalGetDllVersion()
return res
except:
log.warning('Failed to get DLL version')
raise
def get_vendor_string(self):
try:
res = self.__m_dllBasic.CanalGetVendorString()
return res
except:
log.warning('Failed to get vendor string')
raise
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