Add NI-XNET CANFD interface (#968)

* Add initial NI-XNET support
* Add NI-XNET doc
* update authors information
* Add queue len condition to read and use BRS flag to change message type

Author: jaesc

can/interfaces/__init__.py

@@ -27,6 +27,7 @@
     "seeedstudio": ("can.interfaces.seeedstudio", "SeeedBus"),
     "cantact": ("can.interfaces.cantact", "CantactBus"),
     "gs_usb": ("can.interfaces.gs_usb", "GsUsbBus"),
+    "nixnet": ("can.interfaces.nixnet", "NiXNETcanBus"),
 }
 
 BACKENDS.update(

can/interfaces/nixnet.py

@@ -0,0 +1,257 @@
+# coding: utf-8
+
+"""
+NI-XNET interface module.
+
+Implementation references:
+    NI-XNET Hardware and Software Manual: https://www.ni.com/pdf/manuals/372840h.pdf
+    NI-XNET Python implementation: https://github.com/ni/nixnet-python
+
+Authors: Javier Rubio Giménez <[email protected]>, Jose A. Escobar <[email protected]>
+"""
+
+import logging
+import sys
+import time
+import struct
+
+from can import CanError, BusABC, Message
+
+logger = logging.getLogger(__name__)
+
+if sys.platform == "win32":
+    try:
+        from nixnet import session, types, constants, errors, system, database
+    except ImportError:
+        logger.error("Error, NIXNET python module cannot be loaded.")
+        raise ImportError()
+else:
+    logger.error("NI-XNET interface is only available on Windows systems")
+    raise NotImplementedError("NiXNET is not supported on not Win32 platforms")
+
+
+class NiXNETcanBus(BusABC):
+    """
+    The CAN Bus implemented for the NI-XNET interface.
+
+    """
+
+    def __init__(
+        self,
+        channel,
+        can_filters=None,
+        bitrate=None,
+        fd=False,
+        fd_bitrate=None,
+        brs=False,
+        can_termination=False,
+        log_errors=True,
+        **kwargs
+    ):
+        """
+        :param str channel:
+            Name of the object to open (e.g. 'CAN0')
+
+        :param int bitrate:
+            Bitrate in bits/s
+
+        :param list can_filters:
+            See :meth:`can.BusABC.set_filters`.
+
+        :param bool log_errors:
+            If True, communication errors will appear as CAN messages with
+            ``is_error_frame`` set to True and ``arbitration_id`` will identify
+            the error (default True)
+
+        :raises can.interfaces.nixnet.NiXNETError:
+            If starting communication fails
+
+        """
+        self._rx_queue = []
+        self.channel = channel
+        self.channel_info = "NI-XNET: " + channel
+
+        # Set database for the initialization
+        if not fd:
+            database_name = ":memory:"
+        else:
+            if not brs:
+                database_name = ":can_fd:"
+            else:
+                database_name = ":can_fd_brs:"
+
+        try:
+
+            # We need two sessions for this application, one to send frames and another to receive them
+
+            self.__session_send = session.FrameOutStreamSession(
+                channel, database_name=database_name
+            )
+            self.__session_receive = session.FrameInStreamSession(
+                channel, database_name=database_name
+            )
+
+            # We stop the sessions to allow reconfiguration, as by default they autostart at creation
+            self.__session_send.stop()
+            self.__session_receive.stop()
+
+            # See page 1017 of NI-XNET Hardware and Software Manual to set custom can configuration
+            if bitrate:
+                self.__session_send.intf.baud_rate = bitrate
+                self.__session_receive.intf.baud_rate = bitrate
+
+            if fd_bitrate:
+                # See page 951 of NI-XNET Hardware and Software Manual to set custom can configuration
+                self.__session_send.intf.can_fd_baud_rate = fd_bitrate
+                self.__session_receive.intf.can_fd_baud_rate = fd_bitrate
+
+            if can_termination:
+                self.__session_send.intf.can_term = constants.CanTerm.ON
+                self.__session_receive.intf.can_term = constants.CanTerm.ON
+
+            self.__session_receive.queue_size = 512
+            # Once that all the parameters have been restarted, we start the sessions
+            self.__session_send.start()
+            self.__session_receive.start()
+
+        except errors.XnetError as err:
+            raise NiXNETError(function="__init__", error_message=err.args[0]) from None
+
+        self._is_filtered = False
+        super(NiXNETcanBus, self).__init__(
+            channel=channel,
+            can_filters=can_filters,
+            bitrate=bitrate,
+            log_errors=log_errors,
+            **kwargs
+        )
+
+    def _recv_internal(self, timeout):
+        try:
+            if len(self._rx_queue) == 0:
+                fr = self.__session_receive.frames.read(4, timeout=0)
+                for f in fr:
+                    self._rx_queue.append(f)
+            can_frame = self._rx_queue.pop(0)
+
+            # Timestamp should be converted from raw frame format(100ns increment from(12:00 a.m. January 1 1601 Coordinated
+            # Universal Time (UTC)) to epoch time(number of seconds from January 1, 1970 (midnight UTC/GMT))
+            msg = Message(
+                timestamp=can_frame.timestamp / 10000000.0 - 11644473600,
+                channel=self.channel,
+                is_remote_frame=can_frame.type == constants.FrameType.CAN_REMOTE,
+                is_error_frame=can_frame.type == constants.FrameType.CAN_BUS_ERROR,
+                is_fd=(
+                    can_frame.type == constants.FrameType.CANFD_DATA
+                    or can_frame.type == constants.FrameType.CANFDBRS_DATA
+                ),
+                bitrate_switch=can_frame.type == constants.FrameType.CANFDBRS_DATA,
+                is_extended_id=can_frame.identifier.extended,
+                # Get identifier from CanIdentifier structure
+                arbitration_id=can_frame.identifier.identifier,
+                dlc=len(can_frame.payload),
+                data=can_frame.payload,
+            )
+
+            return msg, self._filters is None
+        except Exception as e:
+            # print('Error: ', e)
+            return None, self._filters is None
+
+    def send(self, msg, timeout=None):
+        """
+        Send a message using NI-XNET.
+
+        :param can.Message msg:
+            Message to send
+
+        :param float timeout:
+            Max time to wait for the device to be ready in seconds, None if time is infinite
+
+        :raises can.interfaces.nixnet.NiXNETError:
+            If writing to transmit buffer fails.
+            It does not wait for message to be ACKed currently.
+        """
+        if timeout is None:
+            timeout = constants.TIMEOUT_INFINITE
+
+        if msg.is_remote_frame:
+            type_message = constants.FrameType.CAN_REMOTE
+        elif msg.is_error_frame:
+            type_message = constants.FrameType.CAN_BUS_ERROR
+        elif msg.is_fd:
+            if msg.bitrate_switch:
+                type_message = constants.FrameType.CANFDBRS_DATA
+            else:
+                type_message = constants.FrameType.CANFD_DATA
+        else:
+            type_message = constants.FrameType.CAN_DATA
+
+        can_frame = types.CanFrame(
+            types.CanIdentifier(msg.arbitration_id, msg.is_extended_id),
+            type=type_message,
+            payload=msg.data,
+        )
+
+        try:
+            self.__session_send.frames.write([can_frame], timeout)
+        except errors.XnetError as err:
+            raise NiXNETError(function="send", error_message=err.args[0]) from None
+
+    def reset(self):
+        """
+        Resets network interface. Stops network interface, then resets the CAN
+        chip to clear the CAN error counters (clear error passive state).
+        Resetting includes clearing all entries from read and write queues.
+        """
+        self.__session_send.flush()
+        self.__session_receive.flush()
+
+        self.__session_send.stop()
+        self.__session_receive.stop()
+
+        self.__session_send.start()
+        self.__session_receive.start()
+
+    def shutdown(self):
+        """Close object."""
+        self.__session_send.flush()
+        self.__session_receive.flush()
+
+        self.__session_send.stop()
+        self.__session_receive.stop()
+
+        self.__session_send.close()
+        self.__session_receive.close()
+
+    @staticmethod
+    def _detect_available_configs():
+        configs = []
+        nixnet_system = system.System()
+        for can_intf in nixnet_system.intf_refs_can:
+            logger.info("Channel index %d: %s", can_intf.port_num, str(can_intf))
+            configs.append(
+                {
+                    "interface": "nixnet",
+                    "channel": str(can_intf),
+                    "can_term_available": can_intf.can_term_cap
+                    == constants.CanTermCap.YES,
+                }
+            )
+        nixnet_system.close()
+        return configs
+
+
+# To-Do review error management, I don't like this implementation
+class NiXNETError(CanError):
+    """Error from NI-XNET driver."""
+
+    def __init__(self, function="", error_message=""):
+        super(NiXNETError, self).__init__()
+        #: Function that failed
+        self.function = function
+        #: Arguments passed to function
+        self.error_message = error_message
+
+    def __str__(self):
+        return "Function %s failed:\n%s" % (self.function, self.error_message)

doc/interfaces.rst

@@ -19,6 +19,7 @@ The available interfaces are:
    interfaces/udp_multicast
    interfaces/neovi
    interfaces/nican
+   interfaces/nixnet
    interfaces/pcan
    interfaces/robotell
    interfaces/seeedstudio

doc/interfaces/nixnet.rst

@@ -0,0 +1,20 @@
+NI-XNET
+=======
+
+This interface adds support for NI-XNET CAN controllers by `National Instruments`_.
+
+
+.. warning::
+
+    NI-XNET only seems to support windows platforms.
+
+
+Bus
+---
+
+.. autoclass:: can.interfaces.nican.NiXNETcanBus
+
+.. autoexception:: can.interfaces.nican.NiXNETError
+
+
+.. _National Instruments: http://www.ni.com/can/

setup.py

@@ -31,6 +31,7 @@
     "neovi": ["filelock", "python-ics>=2.12"],
     "cantact": ["cantact>=0.0.7"],
     "gs_usb": ["gs_usb>=0.2.1"],
+    "nixnet": ["nixnet>=0.3.1"],
 }
 
 setup(