Quick code to talk to COM or TCPIP hardware devices

com-port.ipynb

tcpip.ipynb

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   "source": [
    "import socket\n",
    "from time"
   ]
  },
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   "cell_type": "code",
   "execution_count": null,
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   "source": [
    "class TCPClient(object):\n",
    "    \"\"\"\n",
    "    Wraps socket.socket to make it a bit more suitable for receiving and\n",
    "    transmitting terminated strings.\n",
    "    \"\"\"\n",
    "        \n",
    "    TERMINATOR = '\\r\\n'\n",
    "    INPUT_TIMEOUT = 10\n",
    "\n",
    "    def __init__(self, server_ip, server_port):\n",
    "        self._socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)\n",
    "        self._server_ip = server_ip\n",
    "        self._server_port = server_port\n",
    "        # we implement our own buffer just to make bytes_available\n",
    "        # a thing, since socket.socket doesn't have it.\n",
    "        self._buffer = ''\n",
    "\n",
    "    def connect(self):\n",
    "        self._socket.connect((self._server_ip, self._server_port))\n",
    "        self._socket.setblocking(0)\n",
    "\n",
    "    def close(self):\n",
    "        self._socket.close()\n",
    "\n",
    "    def _fill_buffer(self):\n",
    "        is_complete = False\n",
    "        while not is_complete:\n",
    "            try:\n",
    "                self._buffer += self._socket.recv(8192)\n",
    "                time.sleep(0.01)\n",
    "            except:\n",
    "                is_complete = True\n",
    "\n",
    "\n",
    "    @property\n",
    "    def bytes_available(self):\n",
    "        self._fill_buffer()\n",
    "        return len(self._buffer)\n",
    "\n",
    "    def flush_input(self):\n",
    "        self._fill_buffer()\n",
    "        self._buffer =  ''\n",
    "\n",
    "    def write_string(self, string):\n",
    "        self._socket.send(string + TCPClient.TERMINATOR)\n",
    "\n",
    "    def read_string(self):\n",
    "        self._fill_buffer()\n",
    "        message, sep, end = self._buffer.partition(TCPClient.TERMINATOR)\n",
    "        self._buffer = end\n",
    "        return message + sep\n",
    "\n",
    "    def read_string_until_terminator(self, timeout=None):\n",
    "        timeout = self.INPUT_TIMEOUT if timeout is None else timeout\n",
    "        message = self.read_string()\n",
    "        t = time.time()\n",
    "        while len(message) == 0 or ord(message[-1]) != ord(TCPClient.TERMINATOR):\n",
    "            message += self.read_string()\n",
    "            time.sleep(0.01)\n",
    "            if timeout > 0 and time.time() - t > timeout:\n",
    "                raise IOError('TCP input stream timeout waiting for terminator. So far we have: \\n\"{}\"'.format(message))\n",
    "        return message"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
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   "outputs": [],
   "source": [
    "client = TCPClient('192.168.1.120',12321)\n",
    "client.connect()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "client.write_string('IDN')\n",
    "print client.read_string_until_terminator()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "client.close()"
   ]
  }
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