Discovery API
Not all of the features in this interface are required to be supported by all drivers and telescopes. This permits support for a wide range of telescope types without the evils of least-common-denominator designs. Telescope includes properties that permit discovery of supported features and supported ranges of motion rates.Many optional properties can be discovered by simply trying to read or set them. If a property is not supported, trying to read or set it it will raise an exception, which you can trap.
On the other hand, some features must be discovered by reading one of the Can___ properties, all of which must be supported. These are used to discover support for features (such as slewing capabilities) which would alter the state of the telescope if called directly for discovery.
These Can___ properties are intended to declare only that the telescope supports the particular capability. They are not intended to reflect the current state of the telescope/mount. Furthermore, connecting to the telescope may be required in order to determine the capabilities to reflect in the Can___ properties (an error will be raised if a Can___ property is not available). Once connected, however, the Can___ properties must not change.
Finally, the MoveAxis() method supports rate discovery. To discover the supported rates for this feature, a collection of Rate objects is provided. Each Rate object contains a maximum and minimum rate value. They may be equal, in which case the Rate object specifies a single discrete supported rate. The collections may contain more than one Rate object. Each specifies a range of rates or a single discrete rate.