Some lights recieving DMX, others not?

[TommyJ0hns]

Hi,

 

I recently found an article on how to build a cheap USB to DMX dongle using an FTDI chip. Having an active interest in sound and lighting, I took this opportunity at once, using the software Freestyler. However, I have run into an issue. Only 1 light out of my 5 appears to recieve data (A generic, unbranded RGB ParCan). The other 4 (2 Skytec Explorer Scanners and 2 Equinox Party Pars) are not affected by any parameters within the Freestyler software. However, the scanners reset to their home position when disconnected from the DMX source. I'm fairly confident that I have the right addresses on both the lights. I have tried singling out each light, and using the software and adapter on different machines. Any help is much appreciated.

 

Thanks

[david.elsbury]

Sounds like a personality issue within the software- it's not speaking to the lights on the correct channels so it "doesn't do anything ".

 

Have you got any other software that works with the interface to test with? Something that mimics a basic, single preset lighting desk would be best as you can just push "faders" up and see what's happening ?

[Don Allen]

Could also be the timing of your DMX stream. Professional interfaces allow you to change the timing as some fixtures are not fully compliant with the DMX timing structure.

[Ynot]

Don't forget that some (many?) cheaper fixtures with 3-pin in/out may have a pin 2/3 reversal on their inputs - it will only take one of them to have this early in your DMX chain to prevent any other fixture further down the line from working. This is perhaps the simplest explanation and certainly the easiest to prove.

 

Some units will 'see' DMX and do something even though it's not what you're telling it to do from the control end, so it will appear confused, but when as you say you remove the cable and it reverts to home when the signal's gone as it sees a null incoming.

 

If you don't have a reversal cable/adaptor, they're real easy to make up.

 

 

 

 

[TommyJ0hns]

Thank you all for your replies - I have it working.

 

Don't forget that some (many?) cheaper fixtures with 3-pin in/out may have a pin 2/3 reversal on their inputs - it will only take one of them to have this early in your DMX chain to prevent any other fixture further down the line from working. This is perhaps the simplest explanation and certainly the easiest to prove.

 

Some units will 'see' DMX and do something even though it's not what you're telling it to do from the control end, so it will appear confused, but when as you say you remove the cable and it reverts to home when the signal's gone as it sees a null incoming.

 

If you don't have a reversal cable/adaptor, they're real easy to make up.

 

 

 

 

 

Thanks, this was exactly it - I had my suspiscions about this yesterday, and you've confirmed this. Switched around outputs from chip to XLR, working fine, with no issues. Thank you very much! :)