RDM Controller timing clarification

[Dan Scheurell]

I’d like to verify my understanding of the RDM Controller Packet Spacing Times. These are given in Table 3-2 of the RDM spec.

For discovery, a controller sends the command and then waits up to 2.8 ms. If no response, then there are no responders and we move on to the next branch. If there is a response within 2.8 ms, then receive responses until a total of 5.8 ms has passed. So, from the controller's point-of-view, a discovery response always takes either 2.8 ms (no responses) or 5.8 ms (responses).

For normal operation, the controller waits up to 2.8 ms for the response. If no response is received, then wait another 200 us before sending any other packet.

Is this a correct reading of the spec?

Thank you,
Dan

[sblair]

Dan,

Your understanding is pretty close I'd say. My reading of the document would say that as a Controller you must always wait 5.8mS after sending a Discovery packet before transmitting any other packet, including another Discovery Packet.

I'm not sure why we stated in that manner though other than to make sure there isn't any missed traffic as a result of collisions happening. Worst case, if the responders waited until right up until the end of their window to start transmitting and then you have collisions, it might be possible to miss the response and then incorrectly infer that there was nothing in that branch.

Scott