# percent vs. dmx value

Discussion in 'Lighting and Electrics' started by Bobby, Jan 12, 2010.

1. ### BobbyNew Member

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Hey guys, I did a quick search for this and didn't see anything.
I was wondering if anyone had a conversion table for DMX values and what they compare to in percentage. I use a ETC Express 48/96 and we just got some LED lights and it would ease up programming.

Bobby
sleepy and (deleted user) like this.
2. ### FooterSenior TeamSenior TeamPremium Member

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its essentially 2.5 in value to 1%. DMX is a 8bit protocol so you have 255 values in a given DMX slot.
3. ### coldnorth57Member

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it is just simple math 256/100 = X/% so if you want 50% then divid 256 by 2 and that gives you 128 and this works for all % points
4. ### MNicolaiWell-Known Member

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Not really a table, but it's just 255/100 = 2.55/1%. So if you want 50%, quick math gets you to ~127.

+5% = 12.75
+10% = 25.5

5% - 12.75
10% - 25.5
15% - 38.25
...
...
90% - 229.5
95% - 242.25
100% - 255

Most of the time if you do the quick math in your head, that'll get you close enough to the values you want. Granted, it's easier mentally going from percentage to DMX value than the other way around. If you really want a table though it'd take about a minute to make in Excel to whatever level of precision you, be it for every percentage point or every 5 or 10 percentage points.
5. ### starkskETC Technical Support SpecialistPremium Member

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A good thing to note here is that different console models have different ways of handling the rounding that is necessary because there is no such DMX value as 242.25 (for example). Some consoles actually do the math and round up, some round down, and most have a table that is referenced in the console's deep level of programming code that tells it what to output at each percentage point.

To make life more complicated, there is not a "standard" table that every manufacturer uses, or even that is necessarily used between console lines of the same manufacturer.

Moral of the story: Using the division method will get you close, but you may need to do some tweaking to get exactly what you need.

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Thanks guys!
7. ### xanderActive Member

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I just wanted point out what others might have noticed in the above posts. Some people are using 255 and some are using 256. While 1 out of 256 is very small and not too noticeable, the correct value is 256. Like someone said, it is 8-bit, or 2^8, or 256. I am going to assume that people are making this mistake because the values we use are 0-255, but that is actually 256 values because 0 counts too!

-Tim

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While I agree that 1/256 is very small, the difference between 1/255 and 1/256 is orders of magnitude smaller than that. And, 256 is not a DMX value, it is the number of values available. In DMX land, 255=100, so the correct ratio actually is 255/100. As I'm typing this, I'm discovering how insane it is to be arguing this, so I'm going to stop now.
9. ### dcollinsMember

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actually, 255 is right.
0% = 0 DMX
100% = 255 DMX

So, take the percentage and multiply by 255/100 and you'll get the DMX value.

If we use your conversion factor of 256/100, we get 100% * (256/100) = 256 DMX which is an invalid output.

Edit: epimetheus, are you calling me insane?
10. ### derekleffewSenior TeamSenior TeamPremium Member

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Yep, but even more to drive one crazy...
0-255 is 256 (2^8) unique values.
0-65535 is 65536 (2^16) unique values.
0-100% is 101 unique values.

And all this time as an LD you thought you only had 100 choices for each channel.
11. ### xanderActive Member

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Thank you dcollins and epimetheus for correcting me. The ratio off 255/100 is correct. I think what triggered my response was in this post:
12. ### David AshtonActive Member

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It is rather strange that on 12/24 and 24/48 chinese desks costing \$300-500 I can change the display to read dmx or % but not on multi thousand dollar desks.Perhaps ETC could use a Chinese consultant.
13. ### lenWell-Known Member

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I've been developing a reference for my own use over the last few weeks, showing the rgb % for different colors. The base I have been using is 500+ Named Colours with rgb and hex values and then entering them into a spreadsheet using X/255, not 256. I've been doing this since some of my controllers can do percent and others can't. That doesn't really matter anyway because the number and quality of the respective diodes in the fixture will affect the output, so using the same settings on two different brands of fixture will get you different output.

I'd be happy to put my efforts up so far on something that could be collaborated on, maybe google worksheets. Is anyone interested?
14. ### starkskETC Technical Support SpecialistPremium Member

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While there is no further development for the Express line of consoles, our current line of consoles (Congo Family, Eos Family) have the ability to display the DMX value being output.

No consultant needed

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How would one go about this on an Ion? I know I can go to the Background tab in the About screen. Occasionally though it would be nice to be able to hit a key and have the percent values in the channel display change over to DMX.
16. ### starkskETC Technical Support SpecialistPremium Member

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Ok, I guess I should have clarified... You can display what the DMX value is being output from the console (unlike most of Express) but not always from the channel display.

On Ion, the background tab in the About screen is the way to display that information. If you have a device, you can see what ranges the non-intensity parameters are currently set to (useful if you have palettes referenced) by holding [Data] and if that range was set 0-255, you would see the absolute value there as well.

Sorry to get your hopes up. I have filed it in as a customer request for the development team to evaluate.

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Sweet! It's not such a big deal when the fixture definitions are accurate, but I had a heck of a time figuring out a fixture that had a bad definition. I ended up have to switch over to my Artnet->DMX box (Enttec ODE) and the DMX Workbench software to figure out the correct DMX values.
18. ### FooterSenior TeamSenior TeamPremium Member

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This is something the Strand 300/500 series did. On the main screen, you could see the true DMX value in the parameter display.
19. ### philhaneyCBModCB Mods

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I know this is a necropost, but I'm posting to help anyone who comes along and finds this thread in their search for information (I did a Google search for "Convert DMX values to percent" and this thread was the first hit on the list).

If 100% = 255 DMX (as was previously stated), then 1% = 2.55 DMX. Plugging this into Excel, and rounding off, produced the following table:

Click the image to get the larger version. This table is not exact, but it should get you in the ballpark.

Enjoy...

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