DMX Hex Values

Well, in1992, a USITT committee published this formula:

DMX_level = Round(Percentage * (255/100))

But you'll run into consoles now and then that don't precisely follow it.  Perhaps someone from ETC will tell us if this is their "official" internal standard.

For example, almost as long ago, I ran a Colortran Prestige 3000, which didn't use this formula.  Here are the first few lines in a table of values:

Percent  USITT  Colortran
  0%       0        1
  1%       3        4
  2%       5        6
  3%       8        9
  4%       A(=10) B(=11)
...

As I remember, one reason why Colortran used this peculiar system is that, unlike typical ETC disk formats, Colortran had fixed-length records that provided a spot for every channel, even if there was no value present.  So the 0% value had to be non-zero (!) to create a "Blocking Zero" in the file format.  A real zero in the file meant that there was no channel value present in that cue or group.  But more sophisticated file formats only include channel values (and the channel number) when a channel is present.
 

I should have added that the Prestige 3000 actually stored those DMX numbers in the show data.  Most consoles today store percentages instead, which makes more sense-since (in answer to one of your questions) there's usually no way to alter the DMX output for a given percentage displayed on the Stage/Live screen.  But as stated before, you can't be sure of the internal math without a DMX "meter" tool.  It's not what you asked about, but some consoles output intermediate values (001, 002,003...) while they are fading, but many do not-they only output the 101 discrete values for the percentages.

Honestly, the reason I finally bought a Lil DMXter (...on Ebay-a small risk, of course) was because I got tired of road people wasting a lot of time suggesting that our dry lines or DMX cables were at fault, rather than their rented equipment.