Front and back

On the back there are XLR3 DMX-512 connectors, address display and control buttons.

Look inside

On the left there is aluminum circuit board with LEDs. Going to right there is green main control board and power supply.

Control board main chips are 74HC595, MAX485 and unmarked IC that is possibly some MCU. The board seems to be designed for 12V power supply. The circuit board has three small FETs that drive the R, G and B LED control lines according to the controller chip controls. It seem that the LED board has just LEDs (and maybe resistors or other current limiters) and all the actual controlling is is done in the control board.

Power supply

There seems to be fuse F1 on the mains side. Y capacitor seems to be 2.2 nF (222) with 2 kV rating which should be decent but not dual isolation level. How well the transformer is isolated cannot be determined from outside.

Circuit board solder side seems to have decent clearly marked clearance between mains and low voltage side. This looks good.

This seems to be quite OK built device.

On longer run it seems that the DMX-512 input is somewhat unreliable.

It soon became the primary method for linking controllers (such as a lighting console) to dimmers and special effects devices such as fog machines and intelligent lights. DMX has also expanded to uses in non-theatrical interior and architectural lighting, at scales ranging from strings of Christmas lights to electronic billboards.

A DMX512 network employs a multi-drop bus topology where devices are typically daisy chained after each other. A network consists of a single DMX512 controller – which is the master of the network — and one or more slave devices. DMX512 uses unidirectional variable-size packet-based communication protocol.  At the datalink layer, a DMX512 controller transmits asynchronous serial data at 250 kbit/s. DMX512′s popularity is partly due to its robustness.DMX512 data is transmitted over a differential pair using EIA-485 voltage levels on cable with nominal characteristic impedance of 120 ohms. DMX512 does not include automatic error checking and correction, but due to cyclic constant transmission of all data errors due the interference are short temporary problems (just slight light flicker of noticeable at all).

The original DMX512 1990 specified that where connectors are used, the data link shall use five-pin XLR style electrical connectors (XLR-5). DMX512-A (ANSI E1.11-2008) defined the use of eight-pin modular (8P8C, or “RJ-45″) connectors for fixed installations. However three-pin XLR connector is commonly used for DMX512, on lighting and related control equipment, particularly at the budget/DJ end of the market (although that is specifically prohibited by section 7.1.2 of the DMX512 standard).

There is lots of information and project related to DMX512 in Internet. DMX-512 page from Ujjal website has been helping thousands of folks in understanding DMX512 since 1996.

There are some interesting open hardware projects on DMX512. Maybe the most popular is OpenDMX that is DMX512 master interface for PC. The Open DMX USB is inexpensive way to get into the world of controlling DMX devices from a PC. You can buy it as a ready made product or you can build one yourself. It is supported by many control software. It provides no-fuss control of 512 channels with full compatibility with a range of programs.Using a simple application on a PC you can send and also receive DMX512. It is very suitable for example for small live music applications.

Open DMX USB is an open USB to DMX hardware design developed by Enttec. The Open in Open DMX USB refers to the fact that everybody is free to use the design and produce its own USB DMX dongle without paying any licenses.This DMX USB interface is based on the FTDI 232RL chip, that a USB to serial converter. Basically the interface consists of FTDI 232RL chip and RS-485 transceiver chip. This interface design relies  on the computer to handle all the timing of the DMX signal.

Here is my version of Open DMX USB design. I have built this many years ago and it has served me well.

Closer look to the electronics box.

Let’s look inside.

The circuit is built to a small piece of the prototyping board that host only the RS-485 transceiver chip. The USB-serial conversion part is handled by FTDI TTL-232R-5.0V USB- TTL Serial Cable based on FTDI 232RL chip, so all I had to add to it was MX483 chip that converts the serial data top RS-485. I also added few resistor to provide proper RS-485 line termination.

Other angle view.

I have not drawn specific circuit diagram, but this OpenDMX Compatible Unbuffered USB-DMX Interface project page has a good circuit diagram showing what is inside this circuit:

Links to more information:

https://www.enttec.co.uk/en/product/controls/dmx-usb-interfaces/open-dmx-usb/

https://sourceforge.net/projects/opendmxusb/

https://vvvv.org/contribution/opendmx-(devices-enttec)

https://www.openlighting.org/

http://www.OpenDMX.net

Other HW projects:

OpenDMX Compatible Unbuffered USB-DMX Interface project

Your Arduino becomes a OpenDmx USB interface is a tutorial that explains how to use the Arduino as a USB to DMX interface for software that works with OpenDmx. Not that this design works only with an old arduino board that used FTDI chip, and the new Arduino UNO that uses different USB-serial chip (that is not compatible with this application)

DIY USB DMX Interface for under 10$ page describes how to convert a cheap RS485 USB converter to control DMX devices. Some cheap adapters can be used directly, some need some small modifications and some can’t be used. Be sure to get a converter that uses original FTDI chip and not any clones or completely different chips.

Links to software I have used:

QLC+ is a free and cross-platform software to control DMX or analog lighting systems like moving heads, dimmers, scanners etc. QLC+ runs on Windows, MacOS and Linux.

FreeStyler DMX is a free lighting control software used by many dj’s, venues and lighting designers. It can be used together with “Magic 3D easy view” visualizer for FREE.

Other interesting looking links:

https://github.com/paulhayes/UnityOpenDMX

https://github.com/orcaomar/processing-opendmx

https://wiki.openlighting.org/index.php/Open_Lighting_Project

https://wiki.openlighting.org/index.php/Open_Lighting_Architecture

https://stackoverflow.com/questions/15732608/how-to-control-enttec-open-dmx-usb-via-python

https://github.com/davepaul0/DmxPy

It has some reliability issues so I decided to take a look inside. Here are some pics of the product first.

What is inside? Opening few screws shows what is inside.

On the bottom side there is the power supply and control electronics. On the top side there are the circuit board with LEDs. Looks quite decent quality construction considering that this is very cheap Chinese product.

Let’s take a closer look at the power supply that converts the 230V mains voltage to low voltage used by electronics. It seems that the output of the power supply is 12V DC and power rating seems to be 15W (note that I have not verified the voltage with measurement).

The top side of the power supply looks half decent. On the bottom side of the circuit board I would want to see more distance between the mains side and the low voltage side. On some places there seems to be good isolation, but there are also places where the distances are quite small – especially near the opto-isolator. Hard to say what is the quality of the transformer isolation (at least it passed 500V DC insulation testing). The power supply seems to have also fuse on the mains input – there is clearly  a resistor looking fuse or fusible resistor on the circuit board on mains input.

On the bottom there are is a small circuit board connecting the XLR connectors together and another board with control control buttons + address display. I did not dig deeper to the electronics to see if the control processor was in this board on the bottom or in the same circuit board with LEDs.

DMX-512 control channels usage

To experiment with LED conrolling I got one 72W 3 Channel DMX512 Encoder Decoder Board Codering Module for RGB LED Stage Light board from Banggood. This cheap (less than $4) board promises to provide gray-scale 0-100% dimming with 256 * 256 * 256 gray-scale. The board is powered from DC12 ~ 24V and can drive up to 72W (2A*3 Channel). This is exactly what is needed to power high power RGB LEDs or RGB LED strip. Connected with DMX512 controller, the controller will follow the effect of changes on generated PWM outputs. Recommended applications are high-power full-color wall wash lights, spot lights, buried lights, underwater lights, stage lights, tunnel lights.

Here is the board (with some cables connected with test clips).

Here is a look at the backside

According to the product documentation when not associated DMX512 controller will automatically run the built-in effects (colorful hopping, gradient) – this worked as promised. Next test was to use Q Light Controller Plus software and OpenDMX USB DMX-512 output adapter (same setup as I have successfully used earlier) to control the module.

In this testing I needed some suitable RGB LED to control. I decided to use one RGB LED moduke designed for Arduino I had around (MF DIY RGB SMD LED Module for Funduino).

This LED module (MF DIY RGB SMD LED Module for Funduino) is designed to work with 5V Arduino, so running it from 12V  instead of 5V could easily overheat the LED and/or tiny current limiting resistors on board. I finally decided to try my luck by powering theDMX512 Encoder Decoder Board from 8V power supply (the board logic circuits power supply is based on 7805 type regulator, so it should run nicely down to 8V). The testing at 8V was success – both RGB LED and decoder worked well. The decoder board always responds to DMX-512 channels 1-3 (it does not have DMX-512 address switches in it).

I measured that the LED PWM control frequency is 488 Hz, which should be high enough that you can’t see any flickering on LED dimming.

The electronics on the board seem to consist of two MAX1487 RS-485 transceivers, 78L05 regulator, ST 8s003f3p6 microcontroller (STM8 core), 16 MHz crystal, three FETs and some supporting components.

72W 3 Channel DMX512 Encoder Decoder Board Codering Module for RGB LED Stage Light board page as pretty much all the basic information to get the board working, but there seems to be some things are not entirety right. For example this drawing:

The lower pcture parallel method seem to be as it should. But the upper series work seems to have the exactly same drawing – I think that the second decoder board should get the signal from the output of the first board, otherwise connection does not make sense. The boards have for a reason DMX-512 input and output.

On my short testing 72W 3 Channel DMX512 Encoder Decoder Board Codering Module for RGB LED Stage Light board seems to do what it promises on the features I tested. I could not test all the features, because I had only one decoder power and only low power RGB leds.

Pros:

- works as promised

- cheap

- small (18 mm x 36 mm)

- OK quality

Cons:

- this board does not have way to set DMX-512 address it listens to

- mistake in documentation (series connection drawing)

Nowadays when there is a trend that all the communications is converging to use Ethernet, the has been several task forces in converting lighting control to Ethernet. One standard to this direction is ESTA’s BSR E1.17, the “Architecture for Control Networks” protocol (ACN) developed by the live entertainment industry for control of pretty much anything. It is an entirely new protocol.

There are also work going on somewhat simpler approach where you you combine DMX-512 devices and transport the communications over Ethernet where that suits best. For example there are situations where it makes a lot of sense to use computer to send control data to Ethernet network, and at location near the actual lighting equipment convert it to DMX-512 signal. There are several competing protocols for this:Art-Net, Shownet and E1.31 (also called Streaming ACN). There are Art-Net and sACN compatible software, both free & commercial. (FreeStyler, Madrix, Jinx, LoR(E1.31) ……….)

Art-Net is a communications protocol for transmitting the DMX512-A lighting control protocol and Remote Device management (RDM) protocol over the User Datagram Protocol (UDP) of the Internet Protocol suite. It is a trademark of and copyright by Artistic Licence Holdings Ltd., which released the protocol specification into public domain and allows the protocol to be used subject to attribution, but without royalty. Art-Net uses a simple UDP based packet structure designed to provide efficient and low overhead data flow. Art-Net was created by Artistic Licence to overcome the channel restriction of DMX while still utilizing its structure: allows multiple DMX universes to be transported over a single Cat5 cable using ethernet technology. Art-Net I was implemented on 10BaseT network and it uses broadcast. Art-Net II was released in 2006 and it can also use unicast communications. The protocol specification is available for download from the Artistic Licence web site.

E1.31 (also called Streaming ACN) is a protocol for sending DMX512 data over the ACN (E1.17) family of protocols. Streaming ACN (sACN) is a standard protocol developed by ESTA to efficiently transport DMX universes over the network. It is comparable to ArtNET in many aspects. One nice thing is the multicast option allowing very easy configuration. sACN is a popular protocol to control large number of RGB LEDs. E1.31 is expected to become the new standard for transporting DMX over IP, replacing other protocols such as ArtNet and Shownet.

Interesting looking projects related to Art-Net:

ArtNet arduino set v3.1 has implementation of ArtNet receiver and sender working

chris‘s library also implements receiving DMX, working with EtherCard (i.e. the ENC28J60).

Nat‘s library can receive multiple universes and has examples for the NeoPixel library and OctoWS811 libraries. It works with the standard Ethernet library

Arduino Nano + ENC28J60 running 2 universe of WS2812 – sACN/ArtNet

SmartShow Artnet sACN to 2 DMX universe WS2812 Neopixel Driver – Arduino Nano video

Interesting looking projects related to sACN:

E1.31 (sACN) library for Arduino with ESP8266 support

Arduino Nano + ENC28J60 running 2 universe of WS2812 – sACN/ArtNet

ESPixelStick – An E1.31 WiFi Pixel Controller is a pixel driver motherboard for the ESP8266 ESP-01 WiFi module that supports WS2811 / WS2812 pixels

SmartShow Artnet sACN to 2 DMX universe WS2812 Neopixel Driver – Arduino Nano video

I happened to find this AnyTronics 4 channel dimmer thrown out as trash. It looks looks like Anytronics wall mounted dimmer 4 x 10 A that someone has adapted to become rack mounted and moved the DMX-512 address selection switches outside the device. I expected that Anytronics DP410 dimmer pack installation instructions would be about right for this, but after some testing revelealed that that was not the case.

Next task was to look what is inside. This looks as pretty typical 4 channel analogue controller light dimmer, and resembles pretty much the design of newer models. As you can see there are some wires that go to the fuses cut out and most fuse holders missing, So there is something to be fixed before this can be used.

The basic circuitry looks pretty normal. The main board has triacs with heatsinks, control electronics, filtering component (big coils because they need to handle 10A current) and related. The board has pretty good markings what is what in there. It seems that the board is designed so that it can be used to build several different dimmer models (4 and 8 channel dimmers). On the right you can see an extra circuit board that does DMX-512 to anlogue (0-10V) conversion.

The dimmer circuit outlook looks pretty normal. This is four channel dimmer powered from one phase 230V AC 50 Hz mains power. Because the dimmer can output 10A per channel, it will need to be powered from 40A 230V power source if you want to use all the capacity. If you don’t need to use all the power, lower amperage power feed is OK (for example 230V 16A).

The dimmer circuit looks at quick outlook as pretty normal looking analogue dimmer design. There is a low voltage side (powered with one transformer) where there is a ramp voltage generator, and a set of voltage comparators (LM324) that feed opto-isolators. The basic construction of control circuit design look somewhat similat to SchematicsForFree disco power pack and my four channel dimmer pack design. On the mains voltage side of opto-isolators there is circuitry needed to trigger the triacs (powered with the second transformer).

Here is a closer look of the DMX-512 to analogue 0-10V adapter circuit board. The board looks pretty much like homemade circuit board. The main components there 7805 regulator, RS-485 transceiver IC, microcontroller with DMX4ALL label one one IC made by Maxim. This board takes DMX-512 signal and converts it to analogue signal that goes to main dimmer board.

I wanted to test the DMX-512 part, so I needed to fix the problems on the dimmer power wiring, and get suitable hardware + software to generate DMX-512 signals from PC. For harware interfacing I used my pwn USB-to-DMX-512 adapter I had built years ago based on popular open hardware OpenDMX USB design (based on a FT232BM chip and RD-485 transceiver). I did some testing first with  Q Light Controller software that provided easy to use basic light desk  (worked on old Windows XP PC, not with Open DMX adaper on Windows 10 due some driver issues). On the newer PC I started to use Q Light Controller Plus software that worked well.

The end result was that I have now a working DMX-512 controlled light dimmer.