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Python API

deimos

Controller

The control program that communicates with hardware peripherals, runs calculations, and dispatches data.

controller_loss_of_contact_limit property writable

Number of missed packets from a peripheral that indicates disconnection.

dt_ns property writable

[ns] control program cycle period.

enable_manual_inputs property writable

Whether manual input overrides should be applied during the control loop.

loop_method property writable

The loop waiting method for the controller.

Busywaiting is performant, but inefficient; relying on the operating system for scheduling is efficient, but not performant.

loss_of_contact_policy property writable

The response of the control program when a peripheral disconnects during run.

op_dir property writable

The directory where this operation's logs and other data will be placed, and where calcs with linked configuration (like a SequenceMachine) can find their linked files or folders by relative path.

op_name property writable

The name of the operation. Used to set database table names, set log and data file names, etc.

peripheral_loss_of_contact_limit property writable

Number of missed packets from the controller that indicates disconnection.

rate_hz property writable

[Hz] control program cycle rate.

termination_criteria property writable

Criteria for exiting the control program.

__init__(op_name, op_dir, rate_hz)

Build a new controller.

rate_hz will be rounded to the nearest nanosecond when converted to the sample period.

This constructor does not run the controller or attach any peripherals.

add_calc(name, calc)

Add a calc to the expression graph that runs on every cycle

add_dataframe_dispatcher(name, max_size_megabytes, overflow_behavior)

Add an in-memory dataframe dispatcher and return its shared handle.

add_dispatcher(name, dispatcher)

Add a dispatcher via a JSON-serializable dispatcher instance.

add_peripheral(name, p)

Register a peripheral with the control program

add_socket(name, socket)

Add a socket via a JSON-serializable socket instance.

attach_hootl_driver(peripheral_name, transport, end_epoch_ns=None)

Wrap an existing peripheral with a hootl wrapper and start its driver.

available_inputs()

List peripheral inputs that can be written manually.

clear_calcs()

Remove all calcs.

clear_dispatchers()

Remove all dispatchers.

clear_peripherals()

Remove all peripherals.

clear_sockets()

Remove all sockets.

remove_socket(name)

Remove a socket by name.

run()

Run the control program.

run_nonblocking(latest_value_cutoff_freq=None, wait_for_ready=True)

Run the control program on a separate thread and return a handle for coordination.

Parameters:

Name Type Description Default
latest_value_cutoff_freq float | None

Optional second-order Butterworth low-pass filter cutoff frequency to apply to latest-value data. If the selected frequency is outside the viable range for the filter, the cutoff frequency will be clamped to the viable bounds and a warning will be emitted.

 None
wait_for_ready bool

Block until the controller has completed its first cycle.

 True

scan(timeout_ms=10)

Scan the local network (and any other attached sockets) for available peripherals.

set_peripheral_input_source(input_field, source_field)

Connect an entry in the calc graph to a command to be sent to the peripheral.

LoopMethod

Efficient class-attribute

Use operating system scheduling to reduce CPU usage at the expense of degraded cycle performance. Typically viable up to about 50Hz control rate.

Performant class-attribute

Use 100% of a CPU to protect timing. This increases maximum usable control frequency.

efficient() staticmethod

Use operating system scheduling for lower CPU usage.

performant() staticmethod

Use 100% of a CPU to protect timing.

LossOfContactPolicy

Reconnect class-attribute

Attempt to reconnect to the peripheral

Terminate class-attribute

Terminate the control program.

reconnect_indefinite() staticmethod

Construct a reconnect policy with no timeout.

reconnect_s(timeout_s) staticmethod

Construct a reconnect policy with a timeout in seconds.

terminate() staticmethod

Construct a policy that terminates the control program.

Overflow

Error class-attribute

Emit an error and shut down.

NewFile class-attribute

Create a new shard.

Wrap class-attribute

Overwrite oldest data first.

error() staticmethod

Error on overflow.

new_file() staticmethod

Create a new file on overflow.

wrap() staticmethod

Wrap back to the beginning of the file.

Termination

Scheduled class-attribute

End the control program at a specific UTC system time.

Timeout class-attribute

End the control program after some duration from the start of the first cycle.

scheduled_epoch_ns(ns) staticmethod

End at a specified absolute system time in UTC nanoseconds.

timeout_s(s) staticmethod

End after s seconds from the start of the first cycle.