MIDI-MT - Lighting control module

Currently, at reasonable prices, a large number of lighting equipment that support control via the DMX512 protocol has become available.

The DMX512 protocol is designed to control lighting fixtures. It allows you to control 512 channels simultaneously via one three-wire communication line. Depending on the capabilities of the lighting device, you can change the color, brightness, position of the light beam, switching effects and many other characteristics. As a rule, several channels are used on one lighting fixture. Several devices switched on simultaneously allow using the DMX512 control protocol to create light patterns and design elements of varying complexity.

The ArtNet protocol is a network version of the DMX512 protocol. Distributed over a local network by sending to broadcast addresses. In this case, the final equipment must support the ArtNet protocol, or a gate must be installed to convert to the DMX512 protocol.

MIDI-MT supports both of these protocols, both simultaneous and separate operation is possible. Support for both standard 8-bit channels and 16-bit channels has been implemented. They can be used simultaneously, but when designing a network, it must be taken into account that a 16-bit channel takes the place of two 8-bit channels. For example, if you assign a device with four 16-bit DMX channels address 10, then the next free DMX address will be number 18 and not 14.

Settings for the lighting control module

Allows you to control lighting devices and equipment using the «DMX512», «ArtNet» and «BobLight» protocols.

Control Binding Settings

You can assign 8 or 16 bit channels in the configuration editor. To assign a channel, select the required item in the Control refers to light control:

In the last column of settings, in the target group, you need to specify the DMX channel number (address). Possible values range from “1” to “254”.

Configuration file

It is also possible to edit the configuration file in any editor you are familiar with. The main section of lighting control settings looks like this:

  ...
  "lights": {
    "pool": true,
    "dmx": {
      "enable": true,
      "send_bobonly": false,
      "port": 4,
      "type": "AdaLight compatible (momo)",
      "baudrate": 115200,
      "stopbits": 1,
      "timeout": 3,
      "smoothly": 5,
      "name": "USB Serial Port"
    },
    "artnet": {
      "enable": false,
      "port": 6454,
      "universe": 1,
      "ip": "192.168.22.105",
      "mask": "255.255.255.0",
      "broadcast": "192.168.22.255"
    },
    "boblight": {
      "enable": true,
      "port": 19333,
      "ip": "192.168.22.105",
      "start_dmx": 0,
      "reverse_dmx": false,
      "brightness": 0,
      "direction": {
        "colors_type": 5,
        "screen_start": 0,
        "screen_directions": [ 12, 12, 14, 14, 28 ],
        "screen_height": [ 10, 10, 10, 10, 10 ],
        "screen_padding": [ 0, 0, 0, 0, 0 ]
      }
    }
  },
  ...

Repeaters, repeaters and protocol converters

To implement the integration of ArtNet, MQTT and DMX512 network technologies into a single lighting control system, you can use not only equipment from well-known manufacturers. It is much cheaper to use Arduino-like boards for these purposes that support WiFi technology, designed on ESP chipsets, for example ESP8266, ESP32, etc.

At the same time, it turns out to get a device with maximum capabilities at a minimum price. The budget of such a device will cost about the cost of one track lamp, in other words, its cost will be approximately 10-15% of the price of similar branded equipment.

One of these designs, which serves to expand the coverage of a network of controlled devices, runs under the control of the MIDI-MT program, for which it was specially developed. Simplicity of execution and the wide availability of electronic components make it universal. This is a “repeater” that collects control information about the switching status of lighting fixtures from the ArtNet and MQTT networks, then the information is summarized and transmitted via the DMX protocol to the wired network, through which the actual lighting control occurs. Use requires the presence of a wired DMX512 network and a connection point to it.

The repeater can be connected to a DMX512 network consisting of one segment. If the control network is divided into unconnected segments, you can install “repeaters” in each network segment, thereby combining them into a single network. At the same time, the distance of the segments from each other does not matter; it is important that all “repeaters” are connected to a single local network, which implies control via the ArtNet protocol. If it is not possible to provide all “repeaters” with a single local network, you can use control via the MQTT protocol. The standard operating mode of MIDI-MT is the simultaneous use of the ArtNet and MQTT protocols to generate an outgoing DMX stream.

In each lighting network control segment where a “repeater” is installed, it becomes the “Master”, with MQTT control signals taking precedence over ArtNet signals. If the source was enabled using MQTT control, it can only be disabled by it. This applies to any adjustments, both on and off, and to adjusting the brightness or changing the color. On the contrary, if the lighting fixture was turned on by signals from an ArtNet source, further control can be taken over by control signals via the MQTT protocol.

You can read more about multi-protocol “repeaters” and “endpoints” here.