This Indigo 6.0+ plugin allows Indigo to control a Niles Audio Multi-Zone Receiver (ZR-4 or ZR-6) without the need to purchase additional keypads or control points from Niles Audio (though the plugin can work in tandem with those as well.) This plugin connects via a serial connection to the Niles Audio Receiver and is able to both read and set nearly all aspects of the device.
Once installed you will be able to create new Indigo Devices for both your Niles Audio receiver and its attached audio zones. This will give you complete control of your system at both a zone and receiver level. See the forum post (via the More Info link above) for additional details or for assistance!