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Old August 29th, 2013   #2
sblair
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Larry,

Welcome to the forums! The response packet to the DISCOVERY_UNIQUE_BRANCH message is always just a packet data encoded as specified with no BREAK.

To anything else on the wire, it just looks like a single DMX packet with a very long delay in the middle of it.

It may all seem a bit convoluted, but this was done to maintain compatibility with legacy DMX devices that have older UARTs in them that would see the BREAK and then misinterpret the collisions on the wire as a null START code and then interpret following data as DMX data for the fixtures and cause glitching.

Removing the break and then doing the 0xAA, 0x55 encoding causes the enough transitions on the line, even with collisions, that the Discovery collisions of everyone responding back can not be mistaken for a BREAK and null START Code...

Hope that helps explain it.
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