This guide serves as an important update and fix to my previous tutorial titled “DIY USB DMX Interface for Under $10“. Since that tutorial was published, it has become clear that there are multiple versions of this USB-DMX interface board circulating in the market. Depending on where you purchased your board, you may have received one with a chip that doesn’t function properly or is incompatible with the standard DMX data output. This can be frustrating if you were expecting a plug-and-play solution but found yourself with a non-working device instead.
For those who find themselves stuck with such a non-functional chip, this guide offers a practical solution. Thanks to the discovery by GermAndy, it is now possible to modify your existing board to enable proper DMX data transmission. Rather than having to buy a new interface or give up on your project, you can follow these instructions to tweak your board and get it working as intended. This fix ensures that even if your board was sold with a defective or incompatible chip version, you can still achieve reliable DMX control without additional expense.
Requirements
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Non-working RS485 USB Board
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Soldering Iron and Tin
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A steady hand for precise soldering
The Problem
There are multiple versions of the USB RS485 interface boards in circulation, and not all of them work properly right out of the box. The issue lies mainly with the 75176 chip on the board. The DE (Driver Enable) pin on this chip controls when data is sent out, but because DMX data differs slightly from the standard RS485 protocol, the DE pin doesn’t activate as expected. This happens because the DMX protocol doesn’t properly end the transmission in a way the chip expects, so no data is sent.
Solution 1
The first and simplest fix is to lift the DE/RE pin off the board. This means physically cutting or desoldering the pin so that it’s no longer connected to the circuit. By doing this, you allow the 75176 chip to output DMX data without waiting for the protocol to fully complete its handshake. For most boards, this solution should enable proper DMX data output. If it doesn’t work, move on to solution 2.
Solution 2
If lifting the DE/RE pin didn’t solve the problem, the next step is to connect the DE/RE pin directly to the +5V line on the 75176 chip. This forces the chip to always enable its driver, sending out DMX data continuously. Because the chip is very small, a fine-tipped soldering iron is recommended to make this connection carefully. The +5V pin is the VCC on the chip, so refer to the chip diagram to locate it accurately.
Fix for Mac Users (by David P.)
If you’re using macOS El Capitan or later and face driver issues with your DMX interface, follow these steps:
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Install the FTDI D2XX driver from FTDI Drivers. Be sure to read the included README carefully, as some manual terminal commands are required.
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Install the D2xxHelper package from D2xxHelper for Mac.
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Reboot your Mac.
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Install and start your DMX software such as QLC+.
If problems persist, also check out the fix guide for FTDI DMX interface on OS X Mavericks Here
This guide should help you get your USB RS485 DMX interface working properly no matter which version you have. For more discussions and updates, visit: https://diyprojects.tech/diy-usb-dmx-dongle-interface-for-under-10/
For me, only the 2nd solution works.
The chip mounted on the board (ordered to DX) is: T485EEN.
May be, the universal solution is to replace the chip with this: MAX481ECSA+ ( Farnell, 9725130 3,53 € )
Thanks.
Thanks for your reply, the universal solution will probably be replacing the chip but most people can’t change a chip themselves, so i wrote this bypass which is a lot easier and can be done by anyone with some soldering experience.
hi I’m from belgium. I have the save interface and it don’t work. I don’t have good english . Can you explain me what is exactly “lifting the DE/RE pins from the board” how to do that.
Lifting the DE/RE pins means that you disconnect the chip’s DE and RE pins from the board. this can be done by desoldering the pins or just cutting the pins.
If you cannot get this board to work, there is another guide that requires no fix : http://stevenbreuls.com/2014/03/diy-usb-dmx-controller-for-under-10_2_ethernet_cable/
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Dutch : je kan je dmx controller laten werken door de DE en RE pin van de printplaat los te maken zodat deze geen verbinding meer maken. dit kan je doen door deze pins te desolderen of door de pins door te knippen. op de bovenstaande link kan je ook een guide vinden waarvoor geen fix nodig is.
I found another option : On my board, the RE/DE are connected to output C2 of FTDI chip. Instead of desoldering, you can use FTDI software FT_prog to change the pin configuration. Then you don’t need any hardware change.
Details are here : http://falconchristmas.com/forum/index.php/topic,858.msg9877.html#msg9877
That would be a great universal solution, i will test and update the guide ASAP. credits go to you :p
what’s your chip? mine is sp485ee
SP485EE Chips are designed/manufactured by Sipex Corporation, only chips designed by FTDI will work so you will need the FT232RL chip by FTDI. However i’ve not tested other brands throughly so you can give your chip a try.
yes but i’ve the ftdi chip, I was referring to the “chip” (excuse for ignorance) in the image at the top of this page.
The chip in the picture at the top of the page is the 75176B. It is the level shifter which transform the low level signal from FTDI chip to RS485 levels, used by DMX protocol. It is a kind of signal amplifier. Your SP485EE has the same functionality than 75176.
Ok thank you from “arci on the road” from Castellaneta, Italy!!! We solved with second solution, thank you again 🙂
Lifting pins 2 and 3 worked for me. No luck with FT_prog. Production date 2013/06/4 as mentioned by others with this issue.
Additionally, in OSX, I needed to unload FTDIUSBSerialDriver.kext, not sure when or for what I installed it but it interferes with the ftd2xx drivers.
Thanks for the great post Steven and solution GermAndy!
Thanks for the info and great to hear it works for you.
Thanks a lot. Solution 1 helped, I nearly threw it all away !
I’ve tried to use the ft_prog way but when I check C2 is still TXDEN instead of SLEEP. Why is this?
cause your ic is clone and the new ic has eeprom bloqued. its because the ftdi campany has make a drvier that erase the chip clone. so, the chinesse have bloqued it.
is this for real? so no more ftprogging fake chips? where did you find this?
Thing is I’ve found out that it is probs true. Links are inthis thread. Fake chips are blocked. I bought 1pc from the first supplier you recommend and that was fake alas blocked. Ordered from the other supplier and they 3 pcs I bought work just fine.
hmm weird, i can’t seem to brick my device either
Would you please post a link to the chips that you bought and worked for you?
That is quite impossible nowadays, there are soo many different producers/models/revisions there is no clear way to determine what chips work before buying. you just have to cross your fingers they send a working one but you probably will have to apply a fix.
I use the very chip described at the begining and it work pretty well out of the box. BUT! After working perfectly 2 to 3 minutes, sometimes a little more,it will stops sending. The software and the computer itself say that the hardware it’s still connected but it won’t send. As soon as I unplug and plug back the USB from the computer or the “unit” it picks up again and works for another little while. Does anyone have any idea that can help me out?
hmm weird problem, have you tried another pc? mostly it’s just a windows problem.
Probably, I’ll try that!
I tried a different pc and still did the same thing; work for a little while and then freezes. Any suggestions, maybe some setting that I might be able to load with tge FT_Prog. Like I said, all I’ve done is installed the driver and it worked, but it has that problem. Any suggestions on anything that I can try. I really appreciate this.
you could try with only 1 dmx fixture and a short cable, does your controller still crash?
did you figure it out? i’ve got two modules with exactly the same problem.I have no dmx terminator lying around, but the module will stop after a while for 10 seconds and then proceed again, even without any lamp connected. If it stops, the rx led is not blinking. Once it resumes, the lights comes up again.
Weird thing is that the 3d visualiser also stops working (it did however work without any interruption when i was only ‘dry testing’ with a virtual adapter
hmm, you could try other software, also try plugging your usb dmx adapters in a powered usb hub. Its the first time I hear it proceed again after it stopped.
For solution 2 do you first have to lift the DE pin and then connect it to +5V or do you have to leave the DE pin connected to the board and then link it to the +5V pin ?
Thanks.
no both pins are lifted from the board on the image but it really does not matter that much.
What is the proper replacement chip for this, which requires no modification? I bent the leads up, but one of the leads broke. So I can’t try Solution #2. Now I must replace the chip anyway.
Since I’ve already come this far, I’d rather repair this board than to start a new project.
if you find any fake FTDI chip produced before 2015 you should be good, the problem is there is no way to tell what chip will work or not. I’m sorry, it seems the RS485 with RJ45 plug still works out of the box but you must make sure you have the RS485 variant and not the usb network adapter.
Hey Steven,
Im having a bit of a problem trying to get this working. Ive done all the steps but my light just flashes when i plugin the usb cable to the computer.
have you tried another software or lowering the refresh ratio in freestyler?
yes i tried it at 20 and it still does it
hmm, have you tried all fixes?
Hi Steven
I tried many other ways to solve my problem and this only worked !! And not needed another source of feeding only the weld. I paid $ 3 in alli express and rode my dmx dongle I am very happy , thank you for your help Thank Brazil .
good to hear it worked 🙂 have fun.
Hi Steven. i bought a new one usb to rs485 ….. but my fix does not work ( because it was already shorted) ( point of that is that chip can not reset it self… ( it should be only two shorted pins as i understood)
now testing De/Do of level translator ( wich i gues it is) shorting to +5V…. and i recomend shorting it to main rail ( it is easyer to solder…. will provide another feedback)
hey. i have lifted the two pins and the adaptor works for about a minute and then crashes. I have tested in 3 computers and the resoults are the same. Should I sort it to the 5v now or I have another problem?
Thanks
I tested a new batch of adaptors with QLC+.
Not working out of the box with windows 10 and default driver. Re-programing the chip failed, chip locked.
Only solution 2 seems to be working… Seems to be unstable, has disconnected after a while.
Re-booted on Linux: I tried Ubuntu 16.04: Adaptor works out of the box. Stable
Booted on the Raspberry Pi 3 with Raspbian Jessie: Adaptor works out of the box. Stable
I would say that the problem seems more related to the windows driver than to the interface itself.
Or that default linux driver is so ‘elementary’ that it works without any problem…
Choose your camp…;-)
Thanks, this will help a lot trying to find the problem.