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   "source": [
    "# Scales\n",
    "\n",
    "PyLabRobot supports the following scales:\n",
    "\n",
    "- Mettler Toledo WXS205SDU\n",
    "\n",
    "Scales are controlled by the {class}`~pylabrobot.scales.scale.Scale` class. This class takes a backend as an argument. The backend is responsible for communicating with the scale and is specific to the hardware being used."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [],
   "source": [
    "from pylabrobot.scales import Scale\n",
    "from pylabrobot.scales.mettler_toledo import MettlerToledoWXS205SDU"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [],
   "source": [
    "backend = MettlerToledoWXS205SDU(port=\"/dev/cu.usbserial-110\")  # take any ScaleBackend you want\n",
    "scale = Scale(backend=backend, size_x=0, size_y=0, size_z=0)\n",
    "await scale.setup()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "The {meth}`~pylabrobot.scales.scale.Scale.setup` method is used to initialize the scale. This is where the backend will connect to the scale and perform any necessary initialization.\n",
    "\n",
    "The {class}`~pylabrobot.scales.scale.Scale` class has a number of methods for controlling the scale and reading measurements. These are:\n",
    "\n",
    "- {meth}`~pylabrobot.scales.scale.Scale.get_weight`: Read the weight from the scale in grams.\n",
    "- {meth}`~pylabrobot.scales.scale.Scale.tare`: Tare the scale.\n",
    "- {meth}`~pylabrobot.scales.scale.Scale.zero`: Zero the scale."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "=(MettlerToledoWXS205SDU)\n",
    "\n",
    "## Mettler Toledo WXS205SDU\n",
    "\n",
    "The Mettler Toledo XS205 scale is controlled by the {class}`~pylabrobot.scales.mettler_toledo.MettlerToledoWXS205SDU` class. This scale is used by the Hamilton Liquid Verification Kit (LVK).\n",
    "\n",
    "The scale comes with an RS-232 serial port. You'll probably want to use a USB to serial adapter to connect it to your computer. Any $10 generic USB to serial adapter should work (e.g. something that uses FTDI).\n",
    "\n",
    "Note that this scale has a 'warm-up' time after plugging in that is documented as 60-90 minutes by Mettler Toledo depending on the document you like at. In our experience, 30 minutes is sufficient. If you try to take a measurement before this time, you will likely get a \"Command understood but currently not executable (balance is currently executing another command)\" error. Sometimes plugging the power cord in and out will make things work faster."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "0.00148"
      ]
     },
     "execution_count": 3,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "backend = MettlerToledoWXS205SDU(port=\"/dev/cu.usbserial-110\")\n",
    "scale = Scale(backend=backend)\n",
    "await scale.setup()\n",
    "await scale.get_weight(timeout=\"stable\")"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "This scale provides various timeouts:\n",
    "\n",
    "- `\"stable\"`: The time to wait for the scale to stabilize before reading the weight. Note that this may take a very long time to finish if the scale cannot take a stable reading. If you're not using the air enclosure, even being near the scale can cause it to never stabilize.\n",
    "- 0: Read the value immediately\n",
    "- n>0: Try to get a stable value for n seconds. If the value is stable before n seconds, return it immediately. Otherwise, return the value after n seconds.\n",
    "\n",
    "These parameters are available for {meth}`~pylabrobot.scales.mettler_toledo.MettlerToledoWXS205SDU.get_weight`, {meth}`~pylabrobot.scales.mettler_toledo.MettlerToledoWXS205SDU.tare`, and {meth}`~pylabrobot.scales.mettler_toledo.MettlerToledoWXS205SDU.zero`."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "0.00148"
      ]
     },
     "execution_count": 4,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "await scale.get_weight(timeout=0)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Example: getting timing information\n",
    "\n",
    "Let's say you wanted to determine how long it takes to take a measurement. In PyLabRobot, this is easy:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [],
   "source": [
    "backend = MettlerToledoWXS205SDU(port=\"/dev/cu.usbserial-110\")\n",
    "s = Scale(backend=backend)\n",
    "await s.setup()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "100.44 ms ± 6.78 ms\n"
     ]
    }
   ],
   "source": [
    "import time\n",
    "import numpy as np\n",
    "\n",
    "l = []\n",
    "for i in range(10):\n",
    "  t0 = time.monotonic_ns()\n",
    "  await scale.get_weight(timeout=\"stable\")\n",
    "  t1 = time.monotonic_ns()\n",
    "  l.append((t1 - t0) / 1e6)\n",
    "\n",
    "print(f\"{np.mean(l):.2f} ms ± {np.std(l):.2f} ms\")"
   ]
  }
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