View Full Version : DMX to TTL and back from TTL to DMX

04-05-2015, 05:07
I have a need to run DMX over a fiber snake and it already has provisions for 3 ttl tx and rx channels. I am already sending rs232 down one with a converter but would like to build a circuit to send dmx down one of the ttl channel's. Anyone able to draft up a simple circuit or have anything close I can make work quick and easily. The dmx wont need to be altered so shouldn't need to decode it, just convert it and convert it back. If that is possible.

04-05-2015, 05:10
Sounds like something up ekeefe's alley.

04-06-2015, 07:47

dmx is just rs485

04-06-2015, 15:04
Why not use ethernet over the fibre and sCAN or ARTnet to dmx node at other end? These are existing, tried and tested bits of kit.

Check out Artistic Licence here in the UK for details of how and some of the (more expensive but rock solid) bits of existing equipment available to do this. :)

04-06-2015, 19:23
is this fiber part of a digital audio snake? what gear/device is at each end of the fiber?

if you try to attach rs485 converters at each end you might want to check it with a scope to see if it holds integrity. If its going into some kind of audio gear it might be oriented more for a slow ttl signal that is updated at some low rate/unfit for serial data.

04-06-2015, 21:10
well he stated he was sending RS232 (I assume successfully) so I don't see why RS-485 would not work

04-07-2015, 06:16
Well it needs to be dmx from what ever anyone hands me, could be from a wholehog or a grandma or elation or some other dmx device that comes in and needs to use the existing snake. We have 4 conductor fiber and are all readying pushing Ethernet down one of the pairs for other stuff and I plan to sell my non artnet dongle from elation/sudi for sunlite and buy one that can run over ethernet for our own needs. But when people need to use the dmx for their pre programmed stuff its easier to have an dmx channel going down.

The System is an audio snake LightViper by fiberplex, they make an adapter to do 4 universe's and a rs232 over the three ttl ports. But it is really spendy and I prefer to solve it with an economical solution and the rs232 is working rock solid over the ttl conversions. We were even able to get it to interface to the Yamaha console ls9 to talk through the rs232 over the fiber. So I hope to be able to at least get one universe to flow through the snake, the goal is to pull one piece of fiber and be done, pulling one piece of xlr through tubes and such starts a slippery slope.

I bought two of these http://www.ebay.com/itm/2-PCS-MAX-485-MODULE-RS-485-MODULE-TTL-TO-RS-485-MODULE-COMMUNICATION-/251276831775?ssPageName=STRK:MERWX:ACTPNL:LNLK:ITM in hopes it will work out the same way the rs232 works.

04-07-2015, 09:16
it should work fine... DMX is 250Kbps those boards have MAX485's which are good to 2.5Mbits... assuming whatever is doing the TTL>Fiber conversion can handle it

04-10-2015, 07:34
ok i better ask before I start tinkering on my own here I have two identical units and they have DI DE RE RO VCC A B GND I know the VCC is the 5+ and Gnd - and also to the shield of the xlr but thats about where I end. The tutorials all are for aurdrino connectivity between devices how would these need to be setup in my scenario I need full speed transmission from one to another over ttl. And I see certain things need jumpered, anyone familiar with these things?

04-10-2015, 16:08
look up the max 458 datasheet
A & B are the balanced (rs485) I/O
DI is data in (ttl in)
RO is ttl out
DE an RE are data enables, DE pulled high to transmit, RE low to receive. your board has pull up resistors on it