st10_controller

frog.hardware.plugins.stepper_motor.st10_controller

Code for interfacing with the ST10-Q-NN stepper motor controller.

Applied Motion have their own bespoke programming language ("Q") for interfacing with their devices, of which we're only using a small portion here.

The specification is available online

https://appliedmotion.s3.amazonaws.com/Host-Command-Reference_920-0002W_0.pdf

Attributes

Classes

ST10AlarmCode

Bases: IntFlag

The set of possible alarm codes for the ST10 motor controller.

These values are taken from the manual. Note that the alarm code is a bit mask, so several of these may be set at once (if you're especially unlucky!).

Functions

__str__()

Convert the set alarm code bits to a string.

Source code in src/frog/hardware/plugins/stepper_motor/st10_controller.py

def __str__(self) -> str:
    """Convert the set alarm code bits to a string."""
    error_str = ", ".join(code.name for code in self)  # type: ignore[misc]
    return f"Alarm code 0x{self:04X}: {error_str}"

ST10Controller(port, baudrate=9600, timeout=5.0, nadir_offset=0.0, hot_bb_angle=0.0, cold_bb_angle=0.0)

Bases: SerialDevice, StepperMotorBase

An interface for the ST10-Q-NN stepper motor controller.

This class allows for moving the mirror to arbitrary positions and retrieving its current position.

It is assumed that the optoswitch used for homing is connected to input 6 (rising edge). Limit switches, if present, will be disabled.

Create a new ST10Controller.

Parameters:

Name	Type	Description	Default
port	str	Description of USB port (vendor ID + product ID)	required
baudrate	int	Baud rate of port	9600
timeout	float	Connection timeout	5.0
nadir_offset	float	Angle of nadir relative to homing switch (degrees)	0.0
hot_bb_angle	float	Angle of hot black body relative to nadir (degrees)	0.0
cold_bb_angle	float	Angle of cold black body relative to nadir (degrees)	0.0

Raises:

Type	Description
SerialException	Error communicating with device
SerialTimeoutException	Timed out waiting for response from device
ST10ControllerError	Malformed message received from device

Source code in src/frog/hardware/plugins/stepper_motor/st10_controller.py

def __init__(
    self,
    port: str,
    baudrate: int = 9600,
    timeout: float = 5.0,
    nadir_offset: float = 0.0,
    hot_bb_angle: float = 0.0,
    cold_bb_angle: float = 0.0,
) -> None:
    """Create a new ST10Controller.

    Args:
        port: Description of USB port (vendor ID + product ID)
        baudrate: Baud rate of port
        timeout: Connection timeout
        nadir_offset: Angle of nadir relative to homing switch (degrees)
        hot_bb_angle: Angle of hot black body relative to nadir (degrees)
        cold_bb_angle: Angle of cold black body relative to nadir (degrees)

    Raises:
        SerialException: Error communicating with device
        SerialTimeoutException: Timed out waiting for response from device
        ST10ControllerError: Malformed message received from device
    """
    SerialDevice.__init__(self, port, baudrate)

    if timeout <= 0.0:
        raise ValueError("Timeout must be greater than zero")

    if abs(nadir_offset) >= 360.0:
        raise ValueError("Nadir offset must be strictly between -360° and 360°")

    self._reader = _SerialReader(self.serial, timeout)
    self._reader.async_read_completed.connect(self._on_initial_move_end)
    self._reader.read_error.connect(self.send_error_message)
    self._reader.start()

    self._init_error_timer = QTimer()
    """A timer to raise an error if the motor takes too long to move."""
    self._init_error_timer.setInterval(round(STEPPER_MOTOR_HOMING_TIMEOUT * 1000))
    self._init_error_timer.setSingleShot(True)
    self._init_error_timer.timeout.connect(
        lambda: self.send_error_message(
            RuntimeError("Timed out waiting for motor to move")
        )
    )

    # Check that we are connecting to an ST10
    self._check_model_id()

    self._disable_limit_switches()

    # Move mirror to home position
    self._home_and_reset(nadir_offset)

    StepperMotorBase.__init__(
        self, hot_bb_angle=hot_bb_angle, cold_bb_angle=cold_bb_angle
    )

Attributes

HOME_SWITCH_INPUT = 6 class-attribute instance-attribute

The input number for the home switch.

ST10_MODEL_ID = '024' class-attribute instance-attribute

The model ID for the ST10 controller we are using.

STEPS_PER_ROTATION = 50800 class-attribute instance-attribute

The total number of steps in one full rotation of the mirror.

alarm_code property

Get the current alarm code for the controller, if any.

is_moving property

Whether the motor is moving.

This is done by checking whether the status code has the moving bit set.

status_code property

The status code of the device.

For a complete list of status codes and their meanings, consult the manual.

step property writable

The current state of the device's step counter.

This makes use of the "IP" command, which estimates the immediate position of the motor. If the motor is moving, this is an estimated (calculated trajectory) position. If the motor is stationary, this is the actual position.

Raises:

Type	Description
SerialException	Error communicating with device
SerialTimeoutException	Timed out waiting for response from device
ST10ControllerError	Malformed message received from device

steps_per_rotation property

Get the number of steps that correspond to a full rotation.

Functions

close()

Close device and leave mirror facing downwards.

This prevents dust accumulating.

Source code in src/frog/hardware/plugins/stepper_motor/st10_controller.py

def close(self) -> None:
    """Close device and leave mirror facing downwards.

    This prevents dust accumulating.
    """
    StepperMotorBase.close(self)

    if not self.serial.is_open:
        return

    # Don't handle move end events because they will likely happen after the device
    # is disconnected
    self._reader.async_read_completed.disconnect()

    try:
        self.move_to("nadir")
    except Exception as e:
        logging.error(f"Failed to reset mirror to downward position: {e}")

    # Set flag that indicates the thread should quit
    self._reader.quit()

    # If _reader is blocking on a read (which is likely), we could end up waiting
    # forever, so close the socket so that the read operation will terminate
    SerialDevice.close(self)

stop_moving()

Immediately stop moving the motor.

Source code in src/frog/hardware/plugins/stepper_motor/st10_controller.py

def stop_moving(self) -> None:
    """Immediately stop moving the motor."""
    self._write_check("ST")

ST10ControllerError

Bases: DeviceError

Indicates that an error has occurred with the ST10 controller.