Open DMX USB Output

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smokris's picture
First of all, does the Open DMX USB work at all in Mac OS X?

I've spent several hours working on it, but I can't get this thing to work on Mac OS X.. IOKit sees the device and allows me to establish a serial connection with it. I set up the connection and framing like the Linux drivers do, but it just outputs garbage --- my DMX devices flicker uncontrollably.

Any ideas? Chris, would you like to take a shot at this?

Oddly enough, it works perfectly under Windows XP in Parallels.

franz's picture
DMX via Lanbox

I heard this interface performed very well: compared to other packages (i'm not part of their company though)

smokris's picture

Cool, I've looked at lanbox.. But that's about 5 times the cost of the opendmx usb (which I already own)..

But given the crappiness of the ftdi drivers, it might be better to get rid of the opendmx usb and try either the pro version (which according to third-party reviews actually works on mac os x)... or the lanbox-lce.

cwright's picture

Ok, so pretty much FTDI has the worst drivers in the world. Their windows drivers are functional, but the linux ones don't work, and the OS X ones aren't complete either. In fact, while testing today I've discovered that they leave stale device entries in the USB table, which can't be a good practice. Check out and note the 3 (Three!) duplicate entries. This is up from 2 about an hour ago... is undergoing some kind of server migration, as far as I can tell.

cwright@phendrana:/System/Library/Extensions>sudo kextunload FTDIUSBSerialDriver.kext
kextunload: unload kext FTDIUSBSerialDriver.kext failed
cwright@phendrana:/System/Library/Extensions>sudo dmesg
Can't unload com.FTDI.driver.FTDIUSBSerialDriver due to -
com.FTDI.driver.FTDIUSBSerialDriver: FTDIUSBSerialDriver has 2 instance(s)

Wonderful :)

smokris's picture

hm. well, unless you have particularly strong desire to rewrite the ftdi drivers, i think we should probably sell this thing and find a different, non-ftdi interface (see above).

smokris's picture
not dmx usb pro

strike that.. the "dmx usb pro" is ftdi, also.

let's go with the lanbox or something else.

smokris's picture ?

Check out --- there is a test application for a similar interface.

The interface uses the FTDI 245M, whereas the ENTTEC one is FTDI 232BM.. But maybe we can learn from this?

cwright's picture
232BM vs. 245 M

The firmware(this might not even be possible?) or driver for the usbdmx guy apparently sets all the control information correctly at startup, because there isn't a drop of control code in the sample provided; It's fd=open(/dev/blah, O_RDWR); and it Just Works. It does all its I/O in 2 or 3 byte blocks, and apparently doesn't use the DMX protocol at all; I'm suspicious of how this chip actually functions.

The code's 2 years old (march 2005), but compiles fine (after an xcode project upgrade). The device it looks for is /dev/cu.usbserial-DMX, similar to the enttec guy.

the 232BM is a simple fsm (no firmware required; xr while the part used in the schematic at usbdmx is a DLP-USB245M-G, which isn't so simple:

from (google cache because ftdi had a server meltdown recently):

Despite its low cost, the DLP-USB245M-G not only offers the advanced features of FTDI's 2nd generation device but has a quality 4-layer PCB design with solid power and ground planes and an integral 93C46 EEPROM on-board for easy OEM customisation.

franz's picture
DMX without drivers

Curiously, i just realized that LanBox dmx doesn't require drivers or plugins.... Just use your Shell command patch to send a UDP command over the specified adress to the LanBox, and voila ! (i've got a modified Moldul8 version that uses the same trick... and it seems to be working... though i don't have all the DMX hardware to test it right now)

from LanBox LCE Ethernet : Firmware v2.01 supports UDP broadcasting, and UDP based bulk data receiving on the LCX and LCE. This makes distributed universes over EtherNet, and high speed bulk communication with third party applications (like MAX, Capture 3D) possible.