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Subject: Re: [LCtalk] dmx routing
From: Fokko van Duin
Date: Thu, 30 Oct 2003 20:25:11 +0100

At 16:53 +0100 30-10-2003, Eric van Duin wrote:
No, normally you have already max 1 packet time (25ms), now add frame time (LCX interval = 50mS) + another packet time, so about 100ms > delay.

Isn't the packet time a part of the frame time? 50mS frame time resulting in 20 frames per second?

Watch out the wording and definitions of DMX-512 USITT 1990:

A DMX frame is 11 bits (1byte + start & stop bits) = 44uS
A DMX packed is break + maximal 512 frames = about max 23mS, but may take up to 1 second.

The refresh rate to send a packed can be between 44 (highest) down to 1 sec per packed.

The time between frames -may- be 0 (LCX), as it gives the shortest delay between channel 1 and 511, but low cost desks and controllers needs more time for their software to grab next byte. The refresh rate is only important for latency and old moving heads without micro stepping, but 20 refreshes/sec is a common value.


Someone should design a solution! :)

There are mergers doing a better job, but it's complicated (expensive).


--
Fokko van Duin,                     Creators of the LanBox-LC
CDS advanced technology bv,         DMX lighting controller.
http://www.cds.nl/                  http://www.lanbox.com/

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