It is strongly recommended that you use the Chooser object for selecting the driver for the device to be used by your application. It is extremely simple to use, and presents the user with a consistent interface for device selection and configuration. When you connect to a standard driver, you use the ProgID, for example "NexStar.Telescope" in a CreateObject() call. Yiu can see these ProgIDs in the ASCOM Profile Explorer, in the left hand tree pane.
Furthermore, the Chooser has the ability provide your ASCOM/COM speaking app with connectivity to Alpaca devices. It does this by first discovering all of the Alpaca devices of the selected type and adding them to the dropdown list (as **NEW ALPACA DEVICE ....**. If your user selects one, the chooser builds a "dynamic driver" which is an ASCOM/COM driver that converts your app's ASCOM calls into Alpaca, and then replaces the selection in the list with a user-friendly name retrieved from the Alpaca device. Thus your app can talk to an Alpaca speaking device without needing Alpaca code itself.
The chooser returns the selected device's ProgID (including a freshly created ProgID for an Alpaca dynamic Driver). You can pass a (saved) ProgID to the Choose() method, and that device will be pre-selected in the list. The drivers are listed in a special registry area, with the user-friendly name and progID. The Chooser hides all of this from you, and allows us to evolve the registry area without fear of breaking your code. Also, the Chooser provides an interlock which forces the user to pop open the configuration dialog for the chosen device before being able to click OK to change the selected device. It looks like this to the user:
The code to use the Chooser is simple (set a reference to ASCOM.Utilities.Chooser for early binding and IntelliSense):
Dim chsr as New ASCOM.Utilities.Chooser ' This will be a Telescope chooser chsr.DeviceType = "Telescope" ' Retrieve the ProgID of the previously chosen ' device, or set it to "" scopeProgID = chsr.Choose(scopeProgID) ' Maybe save the new telescope choice ProgID here... ' Create the Telescope and connect it. Set scope = CreateObject(scopeProgID) scope.Connected = True ... etc.FYI, the Chooser can be configured to choose any ASCOM device type. The default is "Telescope", but you can change the Chooser.DeviceType property to something else (e.g. "Focuser") and the Chooser will then work for that device type.