Rotator - Device-Specific Responders

This module contains the Rotator device-specific responder classes for the Alpaca REST endpoints which represent ASCOM interface members. You would need to create a module like this for the device you wish to handle in your driver (e.g., Focuser). The interface to each of these responder classes is identical, as described in The Falcon Web Framework but with the Alpaca Device Number as an additional parameter to the on_get() and on_put() methods.

The ASCOM standard interface members (properties and methods) are implemented as separate responder classes here. Incoming Alpaca requests are mapped to the responders. Thus, your device’s low-level control code would be called from within the on_get() and/or on_put() responder functions. Here are the bare interfaces (error handling omitted for clarity). See the Developer Roadmap for details on how the responders work in this template/sample.

Note

The devno parameter carries the Alpaca device number. This is used only if your Alpaca device supports more than one ASCOM device (e.g. two or more Rotators).
The PropertyResponse and MethodResponse classes take a second attribute for returning an Alpaca exception. If omitted, it defaults to Success (no exception).

The maxdev = 1 Constant

This constant is passed as a parameter to all PreProcessRequest() decorators. It is used to range check the device number in requests. It should be 1 unless your Alpaca device supports more than one ASCOM device of this type (e.g. two or more rotators).

Property (GET) Endpoint Responder

This returns a Value in the JSON response (response.text):

Sample GET responder (for a property)

@before(PreProcessRequest(maxdev))
class IsMoving:
    def on_get(self, req: Request, resp: Response, devnum: int):
        value = #whatever your device says
        resp.text = PropertyResponse(value, req).json

Method (PUT) Endpoint Responder

Initiates an action. Normally returns no value. Parameters for the method are carried in the PUT request body, and are encoded as HTTP “form fields”. These are retrieved as a Python dictionary via the Falcon req.get_media() function.

Sample PUT responder (for a method)

@before(PreProcessRequest(maxdev))
class MoveAbsolute:
    def on_put(self, req: Request, resp: Response, devnum: int):
        formdata = req.get_media()
        newpos = float(formdata['Position'])    # Position parameter
        # Whatever it takes to START the action
        resp.text = MethodResponse(req).json

API Responder Documentation

Each class is a responder for that specific member (property or method) of the ASCOM IRotator specification.

Note

Calls to on_get() and on_put() have the same arguments as described above and in The Falcon Web Framework plus the Alpaca DeviceNumber as the last argument.

Attention

The CommandXxx() methods are deprecated. These are left over from the distant past. If you want to implement unique non-standard commands for your device, use the Action() and SupportedActions members. In this sample all of these are marked as not implemented.

class rotator.RotatorMetadata: Metadata describing the Rotator Device. Edit for your device

class rotator.action

Invoke the specified device-specific custom action

See https://ascom-standards.org/newdocs/rotator.html#Rotator.Action

class rotator.canreverse

True if the rotator supports the Reverse method

Seehttps://ascom-standards.org/newdocs/rotator.html#Rotator.CanReverse

Always True for IRotatorV3 (InterfaceVersion >= 3).

class rotator.connect

Connect to the device asynchronously

See https://ascom-standards.org/newdocs/rotator.html#Rotator.Connect

class rotator.connected

Retrieves or sets the connected state of the device

See https://ascom-standards.org/newdocs/rotator.html#Rotator.Connected

Notes

There is a setting sync_write_connected in config.toml that determines whether connecting by writing Connected = True behaves synchronously or acts asynchronously. Conform requires this to be synchronous per IRotatorV3 (PLatform 6).

class rotator.connecting

True while the device is undertaking an asynchronous connect or disconnect operation.

See https://ascom-standards.org/newdocs/rotator.html#Rotator.Connecting

class rotator.description

Description of the device such as manufacturer and model number. Any ASCII characters may be used.

See https://ascom-standards.org/newdocs/rotator.html#Rotator.Description

class rotator.devicestate

List of StateValue objects representing the operational properties of this device.

See https://ascom-standards.org/newdocs/rotator.html#Rotator.DeviceState

class rotator.disconnect

Disconnect from the device asynchronously.

See https://ascom-standards.org/newdocs/rotator.html#Rotator.Disconnect

NOTE: In this sample, Disconnect is instantaneous

class rotator.driverinfo

Descriptive and version information about the ASCOM driver

See https://ascom-standards.org/newdocs/rotator.html#Rotator.DriverInfo

class rotator.driverversion

String containing only the major and minor version of the driver.

See https://ascom-standards.org/newdocs/rotator.html#Rotator.DriverVersion

class rotator.halt

Immediately stop any rotator motion

See https://ascom-standards.org/newdocs/rotator.html#Rotator.Halt

class rotator.interfaceversion

ASCOM Device interface definition version that this device supports. Should return 4 for this interface version IRotatorV4.

See https://ascom-standards.org/newdocs/rotator.html#Rotator.InterfaceVersion

class rotator.ismoving

True if the rotator is currently moving to a new angle

See https://ascom-standards.org/newdocs/rotator.html#Rotator.IsMoving

class rotator.mechanicalposition

The raw mechanical position of the rotator in degrees.

See https://ascom-standards.org/newdocs/rotator.html#Rotator.MechanicalPosition

class rotator.move

Start rotation relative to the current position (degrees)

See https://ascom-standards.org/newdocs/rotator.html#Rotator.Move

class rotator.moveabsolute

Start rotation to the given Position (degrees)

See https://ascom-standards.org/newdocs/rotator.html#Rotator.MoveAbsolute

class rotator.movemechanical

Start rotation to the given new mechanical position (degrees)

See https://ascom-standards.org/newdocs/rotator.html#Rotator.MoveMechanical

class rotator.name

The short name of the driver, for display purposes.

See https://ascom-standards.org/newdocs/rotator.html#Rotator.Name

class rotator.position

Current instantaneous Rotator position, allowing for any sync offset, in degrees.

See https://ascom-standards.org/newdocs/rotator.html#Rotator.Position

class rotator.reverse

The direction of rotation CCW or CW

See https://ascom-standards.org/newdocs/rotator.html#Rotator.Reverse

class rotator.stepsize

Minimum rotation step size (deg)

See https://ascom-standards.org/newdocs/rotator.html#Rotator.StepSize

class rotator.supportedactions

Returns the list of custom action names, to be used with Action(), supported by this driver.

See https://ascom-standards.org/newdocs/rotator.html#Rotator.SupportedActions

class rotator.sync

Syncs the rotator to the specified position angle (degrees) without moving it.

See https://ascom-standards.org/newdocs/rotator.html#Rotator.Sync

class rotator.targetposition

The destination angle for Move() and MoveAbsolute()

See https://ascom-standards.org/newdocs/rotator.html#Rotator.TargetPosition