On Tue, 31 Aug 1999 16:27:03 +0100 Nigel Orr writes: >At 06:22 31/08/99 -0700, you wrote: >> 1. Break >> 2. Mark after break >> 3. Start Code (0x00 for most lighting devices) >> 4. Up to 512 bytes where each byte is a lighting level (0x00 >to >0xff) > >I don't remember the details, but aren't they pairs of address and >level? >Nothing in the above tells you which light is being controlled, and >you can >have lots of lights/dimmers in parallel on the bus. > The standard (using start code 0) does not send addresses. It is assumed that the first byte (after the start code) drives dimmer 1, the second dimmer 2, etc. up to a maximum of 512 dimmers. There have been proposals to include some sort of data compression using RLL or similar, but, at least with a start code of 0, it's just ordered data. It's likely to stay that way for bnackward compatability. Other start codes may use different formats. Harold Harold Hallikainen harold@hallikainen.com Hallikainen & Friends, Inc. See the FCC Rules at http://hallikainen.com/FccRules and comments filed in LPFM proceeding at http://hallikainen.com/lpfm ___________________________________________________________________ Get the Internet just the way you want it. Free software, free e-mail, and free Internet access for a month! Try Juno Web: http://dl.www.juno.com/dynoget/tagj.