first prototype (based to some extent on pycoly)

4 files changed, 625 insertions, 0 deletions

diff --git a/README.md b/README.md
new file mode 100644
index 0000000..1484c48
--- /dev/null
+++ b/README.md
@@ -0,0 +1,6 @@
+# Python library to access Danfoss ULX/TLX inverters over RS-485
+
+* Some code is based on https://bitbucket.org/wagnerflo/pycoly
+* Compatible with micropython and cpython
+* Supports Ping, GetNodeInformation and CAN Messages
+
diff --git a/comlynx.py b/comlynx.py
new file mode 100644
index 0000000..eb9b360
--- /dev/null
+++ b/comlynx.py
@@ -0,0 +1,422 @@
+# Copyright (c) 2012, Florian Wagner <florian@wagner-flo.net> See https://bitbucket.org/wagnerflo/pycoly.
+# Copyright (c) 2018, Yves Fischer <yvesf+git@xapek.org>.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+# 1. Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#
+# 2. Redistributions in binary form must reproduce the above copyright
+# notice, this list of conditions and the following disclaimer in the
+# documentation and/or other materials provided with the distribution.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR
+# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+# EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+# PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+# PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+# LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+# NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+import struct
+
+__all__ = [
+    'hdlc',
+    'Address', 'ProtocolError', 'ParseError', 'Message',
+    'PingRequest', 'PingReply', 'GetNodeInformationRequest', 'GetNodeInformationReply', 'CanRequest', 'CanReply',
+    'Parameters',
+]
+
+
+class hdlc:
+    _fcs_init = 0xffff
+    _fcs_table = (
+        0x0000, 0x1189, 0x2312, 0x329b, 0x4624, 0x57ad, 0x6536, 0x74bf,
+        0x8c48, 0x9dc1, 0xaf5a, 0xbed3, 0xca6c, 0xdbe5, 0xe97e, 0xf8f7,
+        0x1081, 0x0108, 0x3393, 0x221a, 0x56a5, 0x472c, 0x75b7, 0x643e,
+        0x9cc9, 0x8d40, 0xbfdb, 0xae52, 0xdaed, 0xcb64, 0xf9ff, 0xe876,
+        0x2102, 0x308b, 0x0210, 0x1399, 0x6726, 0x76af, 0x4434, 0x55bd,
+        0xad4a, 0xbcc3, 0x8e58, 0x9fd1, 0xeb6e, 0xfae7, 0xc87c, 0xd9f5,
+        0x3183, 0x200a, 0x1291, 0x0318, 0x77a7, 0x662e, 0x54b5, 0x453c,
+        0xbdcb, 0xac42, 0x9ed9, 0x8f50, 0xfbef, 0xea66, 0xd8fd, 0xc974,
+        0x4204, 0x538d, 0x6116, 0x709f, 0x0420, 0x15a9, 0x2732, 0x36bb,
+        0xce4c, 0xdfc5, 0xed5e, 0xfcd7, 0x8868, 0x99e1, 0xab7a, 0xbaf3,
+        0x5285, 0x430c, 0x7197, 0x601e, 0x14a1, 0x0528, 0x37b3, 0x263a,
+        0xdecd, 0xcf44, 0xfddf, 0xec56, 0x98e9, 0x8960, 0xbbfb, 0xaa72,
+        0x6306, 0x728f, 0x4014, 0x519d, 0x2522, 0x34ab, 0x0630, 0x17b9,
+        0xef4e, 0xfec7, 0xcc5c, 0xddd5, 0xa96a, 0xb8e3, 0x8a78, 0x9bf1,
+        0x7387, 0x620e, 0x5095, 0x411c, 0x35a3, 0x242a, 0x16b1, 0x0738,
+        0xffcf, 0xee46, 0xdcdd, 0xcd54, 0xb9eb, 0xa862, 0x9af9, 0x8b70,
+        0x8408, 0x9581, 0xa71a, 0xb693, 0xc22c, 0xd3a5, 0xe13e, 0xf0b7,
+        0x0840, 0x19c9, 0x2b52, 0x3adb, 0x4e64, 0x5fed, 0x6d76, 0x7cff,
+        0x9489, 0x8500, 0xb79b, 0xa612, 0xd2ad, 0xc324, 0xf1bf, 0xe036,
+        0x18c1, 0x0948, 0x3bd3, 0x2a5a, 0x5ee5, 0x4f6c, 0x7df7, 0x6c7e,
+        0xa50a, 0xb483, 0x8618, 0x9791, 0xe32e, 0xf2a7, 0xc03c, 0xd1b5,
+        0x2942, 0x38cb, 0x0a50, 0x1bd9, 0x6f66, 0x7eef, 0x4c74, 0x5dfd,
+        0xb58b, 0xa402, 0x9699, 0x8710, 0xf3af, 0xe226, 0xd0bd, 0xc134,
+        0x39c3, 0x284a, 0x1ad1, 0x0b58, 0x7fe7, 0x6e6e, 0x5cf5, 0x4d7c,
+        0xc60c, 0xd785, 0xe51e, 0xf497, 0x8028, 0x91a1, 0xa33a, 0xb2b3,
+        0x4a44, 0x5bcd, 0x6956, 0x78df, 0x0c60, 0x1de9, 0x2f72, 0x3efb,
+        0xd68d, 0xc704, 0xf59f, 0xe416, 0x90a9, 0x8120, 0xb3bb, 0xa232,
+        0x5ac5, 0x4b4c, 0x79d7, 0x685e, 0x1ce1, 0x0d68, 0x3ff3, 0x2e7a,
+        0xe70e, 0xf687, 0xc41c, 0xd595, 0xa12a, 0xb0a3, 0x8238, 0x93b1,
+        0x6b46, 0x7acf, 0x4854, 0x59dd, 0x2d62, 0x3ceb, 0x0e70, 0x1ff9,
+        0xf78f, 0xe606, 0xd49d, 0xc514, 0xb1ab, 0xa022, 0x92b9, 0x8330,
+        0x7bc7, 0x6a4e, 0x58d5, 0x495c, 0x3de3, 0x2c6a, 0x1ef1, 0x0f78
+    )
+
+    @staticmethod
+    def _fcs(iterator, yield_bytes):
+        fcs = hdlc._fcs_init
+        for byte in iterator:
+            fcs = (fcs >> 8) ^ hdlc._fcs_table[(fcs ^ byte) & 0xff]
+            if yield_bytes:
+                yield byte
+        fcs = fcs ^ hdlc._fcs_init
+        yield fcs & 0x00ff
+        yield fcs >> 8
+
+    @staticmethod
+    def fcs(iterator):
+        return tuple(hdlc._fcs(iterator, False))
+
+    @staticmethod
+    def append_fcs(iterator):
+        return hdlc._fcs(iterator, True)
+
+    control_escape = 0x7d
+    flag_sequence = 0x7e
+    broadcast = 0xff
+    unnumbered_info = 0x03
+
+    @staticmethod
+    def byte_stuff(iterator, additional=()):
+        stuff = (hdlc.control_escape, hdlc.flag_sequence) + additional
+        for byte in iterator:
+            if byte in stuff:
+                yield 0x7d
+                yield byte ^ 0x20
+            else:
+                yield byte
+
+    @staticmethod
+    def byte_unstuff(iterator, count):
+        for i in range(count):
+            byte = next(iterator)
+            if byte == hdlc.control_escape:
+                yield ord(next(iterator)) ^ 0x20
+            else:
+                yield byte
+
+
+class ProtocolError(Exception):
+    pass
+
+
+class ParseError(Exception):
+    pass
+
+
+def _chain(*items):
+    for item in items:
+        try:
+            for i in item:
+                yield i
+        except TypeError:
+            yield item
+
+
+class Address:
+    def __init__(self, network, subnet, node):
+        if not (0 <= network < 16 and 0 <= subnet < 16 and 0 <= node < 256):
+            raise ProtocolError('Invalid address')
+        self.network = network
+        self.subnet = subnet
+        self.node = node
+
+    def as_bytes(self):
+        return (self.network << 4 | self.subnet, self.node)
+
+    def __repr__(self):
+        return "({:02x}-{:02x}-{:02x})".format(self.network, self.subnet, self.node)
+
+    @classmethod
+    def from_bytes(cls, first, second):
+        return cls(first >> 4, first & 0x0f, second)
+
+    @classmethod
+    def broadcast(cls, network=0xf, subnet=0xf):
+        return cls(network, subnet, 0xff)
+
+
+message_types = {}
+
+
+class Message(object):
+    source = property(lambda self: self._source)
+    destination = property(lambda self: self._destination)
+
+    def __init__(self, source, destination, data=()):
+        self._source = source
+        self._destination = destination
+        self._data = data
+
+    def __iter__(self):
+        return _chain(
+            hdlc.flag_sequence,
+            hdlc.byte_stuff(
+                hdlc.append_fcs(
+                    _chain(
+                        hdlc.broadcast, hdlc.unnumbered_info,
+                        self._source.as_bytes(),
+                        self._destination.as_bytes(),
+                        len(self._data), self._type, self._data))),
+            hdlc.flag_sequence)
+
+    def __str__(self):
+        return u'<{}.{} source={} destination={} type=0x{:02x} data="{}">'.format(
+            type(self).__module__, type(self).__name__,
+            self._source, self._destination, self._type,
+            ' '.join(hex(byte) for byte in self))
+
+    @classmethod
+    def unpack(cls, data_bytes):
+        iterator = iter(data_bytes)
+
+        def read(count):
+            return tuple(hdlc.byte_unstuff(iterator, count))
+
+        if read(3) != (hdlc.flag_sequence, hdlc.broadcast,
+                       hdlc.unnumbered_info):
+            raise ParseError()
+
+        source = read(2)
+        destination = read(2)
+        size, type = read(2)
+        data = read(size)
+
+        if (type >> 5) & 0x1 == 1:
+            raise ProtocolError("Application Error")
+        if (type >> 6) & 0x1 == 1:
+            raise ProtocolError("Transmission Error")
+
+        crc = hdlc.fcs(_chain(hdlc.broadcast, hdlc.unnumbered_info,
+                              source, destination, size, type, data))
+        if read(2) != crc:
+            raise ParseError('crc does not match {}'.format(crc))
+
+        if read(1) != (hdlc.flag_sequence,):
+            raise ParseError()
+
+        source = Address.from_bytes(*source)
+        destination = Address.from_bytes(*destination)
+
+        if type in message_types:
+            return message_types[type].unpack_data(source, destination, data)
+        else:
+            raise ProtocolError("Unknown type: {}".format(type))
+
+    @classmethod
+    def unpack_data(cls, source, destination, data):
+        raise NotImplementedError()
+
+
+class PingRequest(Message):
+    _type = 0x15
+
+    def __init__(self, source, destination):
+        super(PingRequest, self).__init__(source, destination, ())
+
+    @classmethod
+    def unpack_data(cls, source, destination, data):
+        return cls(source, destination)
+
+
+message_types[PingRequest._type] = PingRequest
+
+
+class PingReply(Message):
+    _type = 0x95
+
+    def __init__(self, source, destination):
+        super(PingReply, self).__init__(source, destination, ())
+
+    @classmethod
+    def unpack_data(cls, source, destination, data):
+        return cls(source, destination)
+
+
+message_types[PingReply._type] = PingReply
+
+
+class GetNodeInformationRequest(Message):
+    _type = 0x13
+
+    def __init__(self, source, destination):
+        super(GetNodeInformationRequest, self).__init__(
+            source, destination, 29 * (0xff,))
+
+    @classmethod
+    def unpack_data(cls, source, destination, data):
+        return cls(source, destination)
+
+
+message_types[GetNodeInformationRequest._type] = GetNodeInformationRequest
+
+
+class GetNodeInformationReply(Message):
+    _type = 0x93
+
+    def __init__(self, source, destination, data):
+        super(GetNodeInformationReply, self).__init__(
+            source, destination, data)
+
+    def get_product_number(self):
+        return bytes(self._data[0:11]).decode('ascii')
+
+    product_number = property(get_product_number)
+
+    def get_serial_number(self):
+        return bytes(self._data[12:23]).decode('ascii')
+
+    serial_number = property(get_serial_number)
+
+    def get_network_number(self):
+        return self._data[24]
+
+    network_number = property(get_network_number)
+
+    def get_subnet_number(self):
+        return self._data[25]
+
+    subnet_number = property(get_subnet_number)
+
+    def get_address(self):
+        return self._data[26]
+
+    address = property(get_address)
+
+    def get_device_type_id(self):
+        return self._data[27]
+
+    device_type_id = property(get_device_type_id)  # "for future use"
+
+    def get_device_type_sub_id(self):
+        return self._data[28]
+
+    device_type_sub_id = property(get_device_type_sub_id)  # "for future use"
+
+    @classmethod
+    def unpack_data(cls, source, destination, data):
+        if len(data) != 0x1d:
+            raise ParseError("Length of {} is not 29".format(cls))
+        return cls(source, destination, data)
+
+
+message_types[GetNodeInformationReply._type] = GetNodeInformationReply
+
+
+class Parameters:
+    class ULX:
+        # Raw measured values
+        RawInstantEnergyProduction1 = [0x01, 0x01, 0x01]
+        RawInstantEnergyProduction2 = [0x01, 0x01, 0x02]
+        RawInstantEnergyProduction3 = [0x01, 0x01, 0x03]
+        RawInstantEnergyProduction4 = [0x01, 0x01, 0x04]
+        # Smoothed measured values
+        SmoothedInstantEnergyProduction = [0x02, 0x01, 0xd]
+        GridVoltage = [0x02, 0x14, 0xd]
+        GridCurrent = [0x02, 0x15, 0xd]
+        GridFrequency = [0x02, 0x16, 0xd]
+        PVVoltage1 = [0x02, 0x28, 0xd]
+        PVVoltage2 = [0x02, 0x29, 0xd]
+        PVVoltage3 = [0x02, 0x2a, 0xd]
+        PVCurrent1 = [0x02, 0x2d, 0xd]
+        PVCurrent2 = [0x02, 0x2e, 0xd]
+        PVCurrent3 = [0x02, 0x2f, 0xd]
+        # Status information
+        LatestEvent = [0x0a, 0x28, 0x0d]
+        OperationMode = [0x0a, 0x02, 0x04]
+        ModulesInUseMask = [0x0a, 0x02, 0x04]
+        LatestEventModule = [0x0a, 0x29, 0x0d]
+
+
+class CanDataType:
+    NOT_DEFINED = 0x0
+    BOOLEAN = 0x1
+    SIGNED_8 = 0x2
+    SIGNED_16 = 0x3
+    SIGNED_32 = 0x4
+    UNSIGNED_8 = 0x5
+    UNSIGNED_16 = 0x6
+    UNSIGNED_32 = 0x7
+    FLOAT = 0x8
+    VISIBLE_STRING = 0x9
+    PACKED_BYTES = 0xa
+    PACKED_WORDS = 0xb
+
+    @staticmethod
+    def decode(type, value):
+        if type == CanDataType.BOOLEAN:
+            raise NotImplementedError("Boolean not implemented")
+        elif type == CanDataType.UNSIGNED_8:
+            return value[0]
+        elif type == CanDataType.UNSIGNED_16:
+            return struct.unpack('H', bytes(value[0:2]))[0]
+        elif type == CanDataType.UNSIGNED_32:
+            return struct.unpack('i', bytes(value[0:4]))[0]
+        else:
+            raise NotImplementedError('Data type not supported: {} for data: {}'.format(type, value))
+
+
+class CanRequest(Message):
+    """Embedded CAN Kingdom message"""
+    _type = 0x01
+
+    def __init__(self, source, destination, parameter_index, parameter_sub_index, destination_module):
+        super(CanRequest, self).__init__(
+            source, destination, 10 * [0x00, ])
+        self._data[0] = 0xc8
+        self._data[1] = destination_module  # Destination module id
+        self._data[2] = 0xd0  #
+        self._data[3] = parameter_index  # Parameter index
+        self._data[4] = parameter_sub_index  # parameter sub-index
+        self._data[5] = 0x00
+        self._data[6] = 0x00
+        self._data[7] = 0x00
+        self._data[8] = 0x00
+
+    @classmethod
+    def unpack_data(cls, source, destination, data):
+        msg = cls(source, destination)
+        print(data)
+        return msg
+
+
+message_types[CanRequest._type] = CanRequest
+
+
+class CanReply(Message):
+    _type = 0x81
+
+    def __init__(self, source, destination, data):
+        super(CanReply, self).__init__(
+            source, destination, data)
+
+    def value(self):
+        dt = self._data[5] & 0x0f
+        return CanDataType.decode(dt, self._data[6:10])
+
+    @classmethod
+    def unpack_data(cls, source, destination, data):
+        msg = cls(source, destination, data)
+        return msg
+
+
+message_types[CanReply._type] = CanReply
diff --git a/test_asyncio.py b/test_asyncio.py
new file mode 100644
index 0000000..d917e35
--- /dev/null
+++ b/test_asyncio.py
@@ -0,0 +1,91 @@
+# Copyright (c) 2018, Yves Fischer <yvesf+git@xapek.org>.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+# 1. Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#
+# 2. Redistributions in binary form must reproduce the above copyright
+# notice, this list of conditions and the following disclaimer in the
+# documentation and/or other materials provided with the distribution.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR
+# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+# EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+# PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+# PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+# LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+# NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+if __name__ == "__main__":
+    import typing
+    import asyncio
+
+    import serial_asyncio
+    import serial
+
+    from comlynx import *
+
+
+    @asyncio.coroutine
+    def open_serial() -> typing.Tuple[asyncio.StreamReader, asyncio.StreamWriter]:
+        reader = asyncio.StreamReader()
+        ser = serial.serial_for_url('/dev/ttyUSB0', baudrate=19200)
+        protocol = asyncio.StreamReaderProtocol(reader, loop=loop)
+        transport = serial_asyncio.SerialTransport(loop, protocol, ser)
+        writer = asyncio.StreamWriter(transport, protocol, reader, loop)
+        return reader, writer
+
+
+    @asyncio.coroutine
+    def request(reader: asyncio.StreamReader, writer: asyncio.StreamWriter, message):
+        data = bytes(tuple(message))
+        print("Write: {}".format(data))
+        writer.write(data)
+
+        begin = yield from reader.read(1)
+        if begin != bytes([hdlc.flag_sequence]):
+            raise Exception('{}'.format(begin))
+
+        data = begin + (yield from reader.readuntil(b'\x7e'))
+        print("Read: {}".format(data))
+        m = Message.unpack(iter(data))
+        return m
+
+
+    @asyncio.coroutine
+    def ping():
+        reader, writer = yield from open_serial()
+        message = PingRequest(Address(0, 0, 2), Address.broadcast())
+        response = yield from request(reader, writer, message)
+        print(response)
+
+
+    @asyncio.coroutine
+    def get_node_request():
+        reader, writer = yield from open_serial()
+        message = GetNodeInformationRequest(Address(0x00, 0x00, 0x02), Address(0x01, 0x01, 0x3d))
+        response = yield from request(reader, writer, message)
+        print(response)
+
+
+    @asyncio.coroutine
+    def can():
+        reader, writer = yield from open_serial()
+        message = CanRequest(Address(0x00, 0x00, 0x02), Address(0x01, 0x01, 0x3d), *Parameters.ULX.LatestEvent)
+        response = yield from request(reader, writer, message)
+        print(response)
+
+
+    loop = asyncio.get_event_loop()
+    loop.run_until_complete(can())
+
+    print("Close loop")
+    loop.close()
diff --git a/test_plain.py b/test_plain.py
new file mode 100644
index 0000000..6690064
--- /dev/null
+++ b/test_plain.py
@@ -0,0 +1,106 @@
+# Copyright (c) 2018, Yves Fischer <yvesf+git@xapek.org>.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+# 1. Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#
+# 2. Redistributions in binary form must reproduce the above copyright
+# notice, this list of conditions and the following disclaimer in the
+# documentation and/or other materials provided with the distribution.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR
+# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+# EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+# PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+# PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+# LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+# NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+import selectors
+import os
+import logging
+import termios
+import tty
+from comlynx import *
+
+
+def execute(message):
+    with SerialConnection('/dev/ttyUSB0') as conn:
+        data = bytes(tuple(message))
+        logging.debug("Write: %s", data)
+        os.write(conn.fd, data)
+
+        data = b''
+        while conn.wait_for_data(1.0):
+            data += os.read(conn.fd, 8)
+            if len(data) > 1 and data.endswith(b'\x7e'):
+                # one frame is complete then
+                m = Message.unpack(data)
+                logging.debug("Received: %s", m)
+                yield m
+
+
+class SerialConnection:
+    def __init__(self, path):
+        self._path = path
+        self.fd = None
+        self.sel = selectors.DefaultSelector()
+
+    def __enter__(self):
+        self.fd = os.open(self._path, os.O_RDWR | os.O_NOCTTY)
+
+        tty.setraw(self.fd, tty.TCSAFLUSH)
+        iflag, oflag, cflag, lflag, ispeed, ospeed, cc = termios.tcgetattr(self.fd)
+        ispeed, ospeed = termios.B19200, termios.B19200
+        cc[termios.VTIME] = 10
+        cc[termios.VMIN] = 1
+        termios.tcsetattr(self.fd, termios.TCSAFLUSH, [iflag, oflag, cflag, lflag, ispeed, ospeed, cc])
+
+        termios.tcflush(self.fd, termios.TCIOFLUSH)
+
+        self.sel.register(self.fd, selectors.EVENT_READ, 'READ-READY')
+
+        return self
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        self.sel.close()
+        os.close(self.fd)
+
+    def wait_for_data(self, timeout):
+        for key, mask in self.sel.select(timeout=timeout):
+            if key.data == 'READ-READY':
+                return True
+        return False
+
+def main():
+    source = Address(0x0, 0x0, 0x01)
+    ping  =PingRequest(source, Address.broadcast())
+    print(ping)
+    for ping_reply in execute(ping):
+        node_information: GetNodeInformationReply = next(execute(GetNodeInformationRequest(source, ping_reply.source)))
+        device_name = "{}_{}".format(node_information.product_number, node_information.serial_number)
+
+        for field, value in Parameters.ULX.__dict__.items():
+            if field.startswith('_'):
+                continue
+            try:
+                for message in execute(CanRequest(source, ping_reply.source, *value)):
+                    if isinstance(message, CanReply):
+                        print("comlynx.{}.{} value={}".format(device_name, field, message.value()))
+                    else:
+                        raise Exception(field)
+            except ProtocolError as e:
+                logging.error("%s %s", field, str(e))
+
+
+if __name__ == "__main__":
+    logging.basicConfig(level=logging.DEBUG)
+    main()