I presume that you want to just check the status rather than be able to open/close the garage door from Indigo?
When you set up a Virtual Device:
New... >
Virtual Device >
Type = Virtual devices, Model = Virtual On/Off Device, you are presented with a dialogue where you have to fill in Action Groups for
On,
Off,
Toggle. You need to tick
Supports Status and then provide a
Status Variable and a
Status (Action) Group to update the status.
In your case (assuming you don't want to open/close the garage door from Indigo) you don't require the on/off/toggle action groups but you have to set one up. You can set-up a dummy action group that does nothing for these three actions i.e.
No Action. In the variable field specify your variable that you are altering by your script. In the status field specify the Action Group which has your script which returns the value 0 from your rPi - I assume it returns 1 if it is open? Indigo can handle 0 / 1, 'true' / 'false' in the variable used to determine the state. So now when you click the Virtual Device status button in the main Indigo Device List UI, Indigo will run your action group that will run your script that changes the variable depending on garage door state and Indigo will update the Virtual device state accordingly.
Depending how you want the status updated, you could set up a repeating schedule (say every 30 seconds) to do an action:
Device Actions >
Universal Controls >
Request Full Status Update. This would check the state of the garage door every 30 seconds.
Hope that helps - post back if you need more detail.