USB DMX module (FTDI USB DMX)
The USB DMX module is a complete, self-powered, isolated USB to DMX interface, compatible with Enttec Open DMX and Open RDM.
The module provides an easy to use DMX interface by means of a Virtual Com Port (VCP) on the users system. There are no command structures, whatever is sent to the VCP is automatically converted to DMX and vice versa.
- Offers 1kV galvanic isolation (no ground loops and better SNR)
- 3-pin XLR female connector (optional 5-pin)
- 250 kbit data rate, 512 channels
- USB 1.1/2.0 compatible, recommended USB 2.0 full speed host
- Works under Linux, Mac OS X (above 10.9), Windows (7, 8, 8.1 and 10)
- Legacy drivers (for Windows 98, 2000, XP and Vista) available
- Supported by third-party DMX controller tools (as Enttec Open DMX USB) in following software suites: DMXControl 2 and 3, Freestyler DMX, Madrix, PC_DIMMER, Track Wizard, Venue Magic Classic, Vixen Lightning, Q Light Controller (QLC)
The USB DMX module uses the FTDI FT232R USB chip to handle all the USB protocols. The documentation provided by FTDI is very comprehensive. Before using the module, you will need to install FTDI's VCP Drivers. The module with these drivers appear to the system as an extra Com Port.
The USB DMX module features automatic direction turnaround. Under idle conditions, where no data is being transmitted, the module will be in the listening mode, meaning any data that arrives on the module will be transmitted via the USB port to the PC. This direction turnaround can depend on TXEN or RTS signal from FTDI chip and it is selected by onboard jumper.
Short about lighting control
A lighting rig consists of three parts.
- a controller (a lighting desk or a software with proper interface like this USBDMX)
- connectors, cables, converters, spliters
- fixtures (lights, moving heads ...)
DMX — or more specifically DMX512 — is a standard for communication over cables for controling stage equipment. Suitable cables are 110 ohm twisted pair with a shielding acting as a ground with 3 or 5 pin XLR cables on each end. Fixtures are daisy-chained to make a DMX network. This network is referred as DMX universe.
The 512 after the DMX stands for the number of channels one DMX network can handle. One DMX channel controls one parameter, e.g. the intensity of a red light, and is represented by 8-bit value, so the range of intensity is from 0 to 255.
Some fixtures may be using several channels to control various parameters like pan, tilt, red, green, blue, but there are things like single color LED strips with dimmers which can be controlled by a single DMX channel. Each fixture has a preset address, which corresponds to the first channel of DMX data (from 1 to 512) that it is interested in.