Using the Enttec DMX Sender, It is possible to send dmx data over the serial port once one has a usb-dmx interface. However, I am not very sure what to expect from the Encode node.
Let’s say I have a DMX decoder, and would like to control the brightness of an LED connected to CH1 of the decoder’s output. How could I send the 0-255 value to ensure it reaches the CH1?
I assume the byte structure should be something like this:
126: Start of the frame.(Spesific to USB-DMX interface)
6: Sub-command for sending DMX data.
2: Length or number of data bytes following.
0: Reserved.
1: CH1
255: Sets the data for CH1 (0-255) .
231: Checksum or end of frame.
I tested the same hardware with QCL+, and I can easily control the LEDs brightness.
@amir I have opened your patch and tried to understand your question.
In general, the DMX structure is such that each byte of data in the ‘universe’ of 512 bytes is a channel. Roughly speaking, their number in that sequence is the channel number. So if your fixture has 15 channels and it starts at number 10 in the universe, then its second channel will be 11.
Eurolite USB DMX512 probably FTDI based controller and there is a chance that standard OpenDMX technique may be unusable. I have an FTDI based controller and had to write a wrapper for it. For some reason FTDI chips don’t work as simple USB<>SERIAL translators. I think this is done to create more proprietary devices.
Try this: FTDI_DMX.zip (52.4 KB)
It’s kind of prototypical, but I’ve been using it in my projects for a while.
Let’s get this straight.
What equipment are you sending DMX to? Is it an addressable strip? Or some kind of fixture or device?
Is the data you’re sending not getting through at all, or are you seeing data getting through but you don’t like the result?
A single LED is attached to the output of the CH1, and I hope to be able to control its brightness.
Using the “Enttec DMX Sender” to send the data results in some wired behaviours. The same hardware setup behaves as expected once I send the data from QLC+
Not knowing the specifics of your setup or if it is possible to change hardware at all.
That said, wouldn’t it make make more sense to use an artnet LED controller?
eg. pixlite from advatek?
DMX512 decoder (with 4 CH outputs) - you mean there are 4 strip outputs, 4 channels. Is this meant to be RGBW? Roughly speaking, is this a 4 channel fixture? Not addresable led strip on that channels?
All implementations (including mine) of FTDI controllers do not require such a significant header (or I’m missing something). This is the difference between FTDI chip based controllers and a ‘normal’ USB<>RS485 connection.
Got it to work with the SerialPort node alone.
Here is a summary combining @yar tips and some internet searches if someone else is interested:
Data Structure:
The first slice of the spread has to be 0 (0x00)
The following slices of the spread will be N slices of 0-255 for as many channels/slots.
If the Spread count is less than the physical outputs of the DMX512 decoder, the first slice will be taken as the Start byte, and the next slice will be the value of the first channel/slot on the decoder. Note:
Things will get confusing if the spread count sent from vvvv is more than the physical outputs of the DMX512 decoder!
There’s always been a lot of complexity with DMX controllers. The concert equipment market tends to make expensive and proprietary equipment, even though the technology is very old by today’s standards, though reliable. So you can expect very different behaviour from different manufacturers, although it is usually not difficult to get almost any controller to work.
I have made many boards for DMX control - soldering them together from whatever I had, and developing custom devices with microcontrollers, producing them in the factory.
See, for example, this my somewhat outdated device:
I flashed a WLED to this controller and drove 4 channel fixtures (4 channel LED drivers). This requires recompiling the firmware to support DMX, but it’s worth it - out of the box it supports ARTNET over the air and the fixtures can be programmed without a computer, just on the controller via web interface. If for some reason you need similar controllers (but already in a more current revision), then let me know. You’d be surprised that the production cost of such feature-packed boards is less than $10 (usually significantly less).
