OpenTrons Software Development Kit

The point of this repository is to provide a software equivalent to an operating OpenTrons machine, including all related deck modules and instruments (pipettes, tipracks, microplates, etc).

This current version has basic support for keeping track of liquids (and mixtures of liquids) between liquid containers.

It's currently exporting data concerning modules to a separate codebases in charge of running the OpenTrons client. An example of a minimalist Flask client to calibrate and run a protocol can be found at OpenTrons/sdk_demo.

Protocols

Protocols are defined by importing the Protocol class, adding containers and instruments, and finally defining commands.

Every instrument added must have a tiprack of the same size defined within the protocol.

from opentrons_sdk.protocol import Protocol

protocol = Protocol()

# Add containers.
protocol.add_container('A1', 'microplate.96')
protocol.add_container('C1', 'tiprack.p200')
protocol.add_container('B2', 'point.trash')

# Add a pipette (p200)
protocol.add_instrument('A', 'p200')

# Define transfers.
protocol.transfer('A1:A1', 'A1:A2', ul=100)
protocol.transfer('A1:A2', 'A1:A3', ul=80)

Running on the Robot

To run a protocol on the OT-One machine, provide calibration data and then attach the Protocol class to the serial port connected to the robot.

Protocol.run is a generator that will yield the current progress and total number of commands within the protocol upon completion of each command.

To know when each command has been completed by the robot, it sends a special debug command (M62) to the OpenTrons custom firmware and reads from the serial device until the line {"stat":0} is found.

This functionaly can be changed by modifying drivers.motor.OpenTrons.

# Calibrate containers relative to the only instrument.
protocol.calibrate('A1', x=1, y=2, top=40, bottom=50)
protocol.calibrate('C1', x=100, y=100, top=40)
protocol.calibrate('B2', x=200, y=200, top=40)

# Attach to the robot via USB port.
protocol.attach_motor('/dev/tty.usbmodem1421')

# Run protocol.
for current, total in protocol.run():
    print("Completed command {} of {}.").format(current, total)

# Disconnect from the serial port.
protocol.disconnect()

Context Awareness

The Protocol is capable of being context aware, in the sense that it can use data about what's been attached to the protocol in order to fill in variables automatically.

For example, if two pipettes are added to a protocol and a transfer is specified without an explicitly defined axis or tool, the Context Handler is capable of returning a pipette which supports that volume automatically.

Protocol Handlers

The Protocol class itself is in charge of normalizing command arguments, storing them, and passing that data to designated Handlers to perform the work necessary to complete the protocol.

Two Handlers are defined by default, Context and MotorController.

Context Handler

The Context Handler is in charge of keeping track of the state of the robot, calibrations, instruments, and other details using a virtualized deck map with classes that correspond to each labware item.

Other Handlers may take advantage of this context in making intelligent decisions regarding their operations.

Motor Handler

The Motor Handler takes high-level commands from the Protocol class and translates them to serial data (G-Code) in order to perform these actions on the robot itself.

If the Motor Handler is not attached to a USB port, it will still log its movements and the serial commands it would have executed using the standard logging library.

Additionally, the MotorHandler includes a PipetteMotor class which wraps and tries to mimic the interface of a standard Pipette instance from the labware portion of the codebase.

Creating Additional Handlers

Additional handlers can be created by extending from ProtocolHandler. Once you've created a new protocol handler, you can attach it using Protocol's attach method.

The attach method takes a class and returns an instance, which can then be manipulated at will.

Protocol Data Format

From a design perspective, the main responsibility of the Protocol class is to normalize arguments passed to command methods, such as transfer and distribute.

These calls are then stored within the class to be sent during the appropriate times to any attached Protocol Handlers.

The data format is meant to be isomorphic with the OT-One JSON protocol, meaning that ingesting and exporting to our legacy format should be a simple exercise.

Compilers

This library has support for custom compilers, which will generate protocols in JSON format to run on the original OT-One software.

FusX

The only compiler currently in service is the one running on the backend of Mix.Bio's FusX page.

This code can be called through the library by importing the pfusx module from compilers.

Multiple sequences can be defined in either DNA or RVD format and compiled into a single protocol output file.

from opentrons_sdk.compilers import pfusx

inputs = [
	'NI NG NI HD HD NN NG HD NG NG NI NG NG NG NG',
	'ATACCRTCTTATTT'
]

pfusx.compile(*inputs)

CSV Plate Maps

A utility for working with CSV Plate Maps is defined within the compiler section of the framework. Example plate map CSVs can be found in the test fixtures, as well as the compiler data directory.

This allows third parties to specify well layouts within Excel and then utilize that information for the creation of protocols.

Currently, this functionality is being used in the FusX compiler to replace the original SQLite database from Mayo specifying plate positions, as well as in a test for Tipracks to ensure proper tip offset order.

Command Engine

A command engine is provided to allow for the specification of high-level syntax for human readable commands.

A decorator is provided to allow for setting complex syntaxes and then passing parsed arguments from string-based input into the handler methods.

This functionality can be utilized within a Protocol Ingestor and perhaps a formatting system such as YAML to provide a new protocol language to replace the JSON protocols.

Argument Definition

Arguments are defined via regular expressions and given names as well as human-readable examples of what the input should look like.

For example, the code below creates an argument syntax for a plate definition.

define_argument(
    'plate',
    '(([A-Z][1-9])|(\w+)):(([A-Z][1-9])|(\w+))',
    'A1:A1 or Plate1:A1'
)

Command Definition

A function decorator is provided for the definition of full command syntax.

The name of the method decorated becomes the name of the command.

The syntax string is composed of argument tags, which will be automatically parsed by the execution handler (execute) and applied to the function.

An argument tag is a name of a defined argument within angular brackets (< and >). To define a label for an argument, place a colon after the argument name and follow it with the desired argument name.

If no argument name is provided, then the argument will be passed as its base argument name.

Documentation for the command handler can be provided to the user interface by utilizing Python's docstring access, available as fn.__doc__.

Additionally, metadata regarding argument definitions (as specified within define_argument) may also be sent to the user interface.

@syntax('<volume> from <plate:from_plate> to <plate:to_plate>')
def transfer(volume=None, from_plate=None, to_plate=None):
    """
    Transfers the specified amount of liquid from the start
    plate to the end plate.
    """
    # [...]

Full example

from opentrons_sdk.engine.commands import define_argument, syntax, execute

define_argument(
    'plate',
    '(([A-Z][1-9])|(\w+)):(([A-Z][1-9])|(\w+))',
    'A1:A1 or Plate1:A1'
)

define_argument(
    'volume',
    '\d+[umµ]l',
    '10ul, 10ml, 10l, 10µl, etc.'
)

protocol = Protocol()

@syntax('<volume> from <plate:from_plate> to <plate:to_plate>')
def transfer(volume=None, from_plate=None, to_plate=None):
    """
    Transfers the specified amount of liquid from the start
    plate to the end plate.
    """
    protocol.transfer(volume, from_plate, to_plate)

execute("transfer 10µl from A1:A1 to A2:A2")

protocol.run()

Labware

Positions

Positions throughout this library are normalized into zero-indexed tuples based on column letter and row number. For example, "A1" becomes (0, 0). Tuples may be passed to any system where a position argument is valid.

Full addresses of a deck slot and well within that slot are indicated with a colon in string format ("A1:A1") and as a list of tuples in normalized format ([(0, 0), (0, 0)]).

Deck

All containers added to a Protocol are ultimately added to a deck, as part of the "Virtual Robot" that runs the handler.

You can search for modules on the Deck by using find_module with keyword arguments representing filters.

The filters work on dynamic properties as well, for example has_tips on Tipracks.

tiprack = deck.find_module(name="tiprack.p200", has_tips=True)

Pipettes

Unlike containers, which are calibrated within the Context Handler, Pipettes store their calibration values within the base labware class. This is because Pipettes will use their interal calibration values to make potentially complex calculations based on volume.

Data collection and a more detailed supports_volume algorithm can account for working volumes. It's possible to get increased accuracy from physical pipettes by doing a distribution call using a larger volume instead of a single transfer of a smaller volume.

Multi-channel pipettes are left as an exercise for the reader. In the current implementation, multi-channel transfers are simply specified as single transfers on the axis of a multi-channel pipette.

Well Volumes

A complex liquid inventory system has been added to the labware containers.

Most of this functionality has been disabled for the time being, but could be very useful to the creation of a more advanced protocol editor.

Containers

The labware.containers module provides data about all supported containers, as well as conversions between old and new data formats.

Containers can be specified by the user.

Listing Containers

from opentrons_sdk.labware import containers

list = labware.containers.list_containers()

Defining a Container

Containers definitions are stored in config/containers. These are YAML files specifying the base type of container, the number of columns and rows, the A1 offset, and well margin.

See the documented example container for more detailed instructions.

For containers with varying well or tube sizes, you can specify each variation as a custom_well within the YAML structure. See the 15-50ml tuberack for an example of this functionality being used.

Getting Container Well Offset

All container classes provide a static interface for getting non-calibrated well offsets, which are all in reference to the A1 (or first coordinate) of each plate.

from opentrons_sdk.labware import containers

microplate = containers.load_container('microplate.24')
microplate.offset('A1')

Tipracks and Tip Inventory

Containers of the Tiprack type have the ability to return the position of a tip from a given offset number of tips (which represent the tips that have been used during the operation of the robot).

For example, the code below will provide the offset to the eleventh tip position, in the event that the first ten have already been used.

A CSV containing a Plate Maps of tip offset order can be found in the test fixtures. If the order is changed, so should the offset map to ensure that the tests pass.

Tip offset can also be set at the Protocol level, and will allow the user to specify how many tips have been used in a particular rack and automatically switch to the next rack with remaining tips.

from opentrons_sdk.labware import containers

tiprack = containers.load_container('tiprack.10ul')
tiprack.tip_offset(10)

User-Specific Containers

Users can provide their own YAML files specifying custom containers. These containers can be stored anywhere, but must be loaded within the containers module before being accessible.

This can be set to automatically load from a preloaded folder in the users' documents for the desktop client.

from opentrons_sdk.labware import containers

containers.load_custom_containers('/path/to/containers')

This will do a recursive glob through the directory provided and add all YAML files to the list of available labware containers.

Supported Container Types

As of this writing, supported container types are as follows:

Grid (all containers extend from this base)
Legacy (containers specified within the old containers.json format)
Microplate
Reservoir
Tiprack
Tuberack
Point

For an up-to-date list, please use the containers.list_container_types() method.

These types are implemented in the internal code and are currently not extendable by the end user.

License

Yuffster/opentrons_sdk

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