RDM Discovery packets

[sblair]

To clarify, a responder MUST respond within 2ms. A controller must listen for a response for up to 2.8ms.

It is up to you when you discover devices connected to you. Generally it is something that you want to have some user configurable options for. Typically I'd suggest doing a discovery shortly after you first come up and then you can do an ongoing discovery when you want. I'd suggest no more frequently than once/minute or so. It's also a good idea to do it whenever you see the controller above you doing discovery as well. If the controller above you is hardly ever doing discovery then there isn't much need in you doing it more frequently than it. Again, user configurable options here are a good idea.

Port ID can be useful in some larger systems, especially for dimmer racks that consume multiple universes of DMX for it to understand the source where it's data is originating. If you don't make use of the Port ID field as a responder receiving it you can choose to ignore it. On the Controller-side, you need to properly generate the correct Port ID though.