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Old July 29th, 2009   #2
Task Group Member
Join Date: Aug 2008
Posts: 369

My interpretation is that each sub-device *could* have a different set of personalities.

Per section 9.2.3: "All sub-devices shall report an identical list for SUPPORTED_PARAMETERS." Other than that, there are relatively few restrictions on sub-devices.

I see nothing in the document that requires all sub-devices to have the same personalities.

I agree that there should have been a GET_SUPPORTED_SUBDEVICE_IDS PID in the document. As I recall, allowing gaps in the sub-device list came up relatively late in the development of the document as a way of dealing with dimmer racks that have modules removed. This detail slipped through the cracks.

Fortuntely, in most cases the sub-devices will be sequential, or nearly sequential. You can query each sub-device starting at 1 and work up the list until you've found the proper number of devices. You're unlikely to have a responder with 3 sub-devices numbered as 157, 393, and 503.
ericthegeek is offline   Reply With Quote