e01b072.PDF

ELECTRONICS ONLINE

DMX 512

protocol, software and interfaces

By Harry Baggen

In recent issues we have regularly devoted attention to the DMX-512 sys-

tem. Several construction projects have already been published, and more

are sure to follow. An enormous number of companies that make or sell

commercial DMX products can be found on the Internet. For the DIYer,

though, there are not all that many DMX projects. However, there are

still a few interesting designs and informative sites to be found.

The DMX standard was originally intended to

be used for theatre lighting systems. In the

meantime, the possibilities of the system and

the available equipment have been extended

to the point that it can be used for much more

than just controlling lights at a distance. Of

course, this is not news to regular readers of

Elektor Electronics , since we already published

an article about the protocol in the May issue

of this year. Naturally, there is a lot more that

can be said about the DMX protocol than what

we presented in a few pages in that issue.

The full DMX standard is published by the

USITT (United States Institute for Theatre

Technology). The complete version of the

standard is available in printed form, but only

portions are available on the Internet. How-

ever, information and news of the latest

developments are provided by the USITT web

site [1]. To order the DMX standard in Europe,

contact the PLASA (Professional Lighting and

Sound Association) [2].

Besides these official sources, there are vari-

ous sites maintained by DMX users and fans

that provide useful information about the pro-

tocol. Although this information is never

complete, most users probably do not need to

know everything. We have searched out a

few interesting sites in several different lan-

guages. At DMX512.COM [3] and The

anatomy of DMX512 [4] the language is Eng-

lish, at Soundlight [5] it’s German and at

Ressources Techniques [6] it’s French.

A site that addresses all aspects of DMX is

Ujjal’s DMX512 Website [7]. This extensive

site is very practically arranged and

also deals with DMX problems. In

addition, there is a large collection of

links related to DMX, including all

known manufacturers of DMX equip-

ment. Furthermore, there is a down-

load section for DMX software and

hardware.

There are also several DMX FAQs

available on the Internet. Most of

these are obviously not particularly

current. For example, we found three

addresses having the same FAQ list,

with only the revision date being dif-

ferent — and all around five years

old! One FAQ site we should men-

tion is DMX512 mini-FAQ [8], since

the contents are still quite useful in

spite of their age (they deal primar-

ily with basic issues).

If you want to start working with

DMX hardware and software, you

will need to know not only the organ-

isation the protocol, but also the

Elektor Electronics

11/2001

ELECTRONICS ONLINE

and the schematic diagram and hex code ﬁle

for a 12-button DMX ﬂasher.

The Electronic Projects pages of Christian

Mohr [13] contain various attractive electron-

ics projects. Two DMX projects that are cur-

rently under development are a PC/DMX

interface and a DMX receiver.

At the site of another DMX-512 fan, Adam

Davis, you can find a description of a small

DMX controller implemented using a PC [14].

This is also still in the experimental stage,

but it should be interesting to keep an eye on

how it develops.

LPR2DMX [15] is a very small printer inter-

face for the PC that supports DMX-512 com-

munications. This interface can be controlled

using a Linux driver that can be found under

the name of DMX4Linux at the Cubic site

[16]. This driver supports several other (com-

mercial) DMX interfaces in addition to the

LPR2DMX.

(050101-1)

codes to which the equipment from

various manufacturers responds.

Information on this subject is cer-

tainly available. There are two impor-

tant summaries: the ESTA has a page

with DMX Usage Data [9], and a

DMX Protocol Library [10] is avail-

able from Interactive Technologies.

Hardware and software develop-

ments can be found only sporadi-

cally on the Internet, but they will

probably become more frequent with

the increasing popularity of DMX for

hobby applications.

In particular, linking a PC with a

DMX-512 system appears to interest

many designers. For example, there

is an AVR DMX-512 dongle for PCs

[11]. This is a small interface build

around an AVR microcontroller and

an RS-485 transceiver IC. The circuit

is connected to the printer port of

the PC. The associated software is

written in C. The author makes both

the hardware and the software avail-

able for download from his site.

Another printer port interface is

available at Kristof’s Webpage [12].

The schematic diagrams and hex

code ﬁles can be downloaded free of

charge. Here you will also find the

schematic diagram of a DMX booster

Internet addresses

[1] USITT:

www.usitt.org/DMX/DMX512.htm

[2] PLASA:

www.plasa.org

[3] DMX512.COM:

www.dmx512.com/web/light/dmx512/

index.htm

[4] The anatomy of DMX512:

www.euro-pa.be/dmx.html

[5] Soundlight:

www.soundlight.de/techtips/dmx512/

dmx512.htm

[6] Ressources Techniques:

http://ogloton.free.fr/dmx_512/

presentation.html

[7] Ujjal’s DMX512 Website:

www.geocities.com/dmxpage/

[8] DMX512 mini-FAQ:

www.lightresource.com/dmx512fq.html

[9] DMX Usage Data:

www.esta.org/tsc_dmx_data/

dmx-cat.htm

[10] DMX Protocol Library:

www.interactive-online.com/library/

[11] AVR DMX-512 dongle for PC’s:

www.ele.tut.ﬁ/~viikari

[12] Kristof’s Webpage:

http://users.skynet.be/kristofnys/

[13] Electronic Projects:

www.hb.se/cmo/projekt/default.htm

[14] Adam Davis:

www.ubasics.com/adam/electronics/

dmx512.shtml

[15] LPR2DMX:

www.lighting-solutions.de/products/

LPR2DMX/index.html

[16] DMX4Linux:

http://llg.cubic.org/dmx4linux/

11/2001

Elektor Electronics

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