Wireless DMX Weirdo!

Robert F Jarvis

Well-Known Member
We have several groups of LEDs, each group fed from a wireless DMX receiver. All worked well until I got called out because all the LED fixtures were not responding to any commands! On inspection a newly placed ADJ COB Canon (on the floor) was found to have had its mode changed to "Slave". Now for the interesting part; It's wireless DMX receiver was pulsing red (rather like the DMX wireless transmitter). And even then the question remains. If this fixture was in a wrong mode how did it a/ change the receiver to red and more importantly b/ how did that stop ALL the other wireless connected fixtures working? Finally; when the Canon's mode was set back to DMX a/ the Rx pulsed green (per norm) and b/ all the other LED fixture groups worked perfectly.

A receiver transmitting!!!!!!
 
1. Confirm that Slave mode only receives. I expect it does, but always double-check. Does it try to talk to a master bidirectionally for any reason? If it should only receive, then:

2. Is the problem repeatable? Can you intentionally switch back and forth between Slave and DMX and see exactly the same symptoms occur?

3. Can you confirm that valid DMX data is coming out of the fixture when it’s in Slave mode? The best way to do this is with a DMX tester, like a DMXter or a DMXcat (there are several others, as well).

If you can’t replicate the problem (the answer to 2 is no) then it was a spurious or random event. This could simply be unexplainable and never happen again, or it could be a firmware bug in the fixture.

In any case, take the results of the above tests to ADJ tech support. That’s the information they’ll need and they are who you should talk to going forward.

Jim
 
I have not way without going to ADJ that this unit transmits. And as a slave why would it. Yes, very repeatable. I really need to get a DMX tester. Having said that why would a DMX signal come out of a DMX in port or are the IN and OUT a though bus (with the electronics just sniffing what DMX data on its addresses? I was going to take it to the guys who make the wireless dongle but your note about ADJ (an does the unit Tx) also makes sense. Thanks
 
Many devices, including ones that I design, have DMX in and out directly connected together. Provided the circuitry in the fixture is designed to be high-impedance when it’s not powered (which is required to be compliant with the DMX protocol), DMX data will pass through a failed fixture, or a fixture that has no power.

I have no idea how sophisticated an ADJ master/slave setup would be, I know nothing about it. Overthinking it for a minute, I could envision a master that can query connected devices using RDM and then accommodate differences in fixture profiles so that slaves don’t all have to be the same model as the master. Something like that would result in slaves returning data to the master.

It wouldn’t surprise me at all if a low-cost wireless device doesn’t correctly differentiate between DMX channel data and RDM device response data. RDM from a controller will go through the wireless link, unless the wireless specifically filters out packets with the RDM start-code. This will invoke RDM responses from fixtures, even though those packets (most likely) won’t be understood by the wireless receiver and will not be wirelessly returned to the controller. Very few wireless DMX systems support RDM (one very notable exception being LumenRadio CRMX, which does it beautifully, provided you use their RDM capable transmitter).

Anyway... I’m just rambling. It’s definitely ADJ you want to talk to.

Jim
 
Was very surprised by all the responses. Great forum. Looking back with this new found knowledge it now make sense. Anyway - I'll sleep better tonight and be better prepared for next time (there is always a next time). Thank you
 
Was very surprised by all the responses. Great forum. Looking back with this new found knowledge it now make sense. Anyway - I'll sleep better tonight and be better prepared for next time (there is always a next time). Thank you
@FJarvis Possibly include a hand-held, battery powered, (Battery powering avoids ground loops.) DMX reader on your Christmas or Hanukah list OR find a cheap 'n cheerful one; more and more affordable units are available all the time. Honest; even the simplest RELIABLE tester will let you sleep better at night and lessen strain on your heart. Ask around; you may already know someone who'd either loan you theirs for a day or two OR, even better, visit at a mutually convenient time and illustrate how very VERY useful an affordable RELIABLE reader / tester is. A DMX reader / tester will RAPIDLY become your friend for life; even better if you acquire one that not only reads DMX but transmits known values on known addresses upon demand at the press of a few buttons. I bought my Goddard Lil' DMX'ster when Goddard first introduced them; up here in Canada it cost me well north of Canadian $400 by the time I imported it and paid taxes, custom's duties and shipping. In spite of the cost, I've NEVER regretted my purchase. In our present times, many, MANY, manufacturers have brought reliable products to market at APPRECIABLY lower price points.
'nough said.
Toodleoo!
Ron Hebbard
 
IIRC, with the ADJ wifly capable fixtures I've used, you have been able to use a fixture to transmit if you don't have/want to use a separate adapter. So yes, receivers transmit!

I had a similar but opposite problem once- An LED rig dmx cabled up, with a few ADJ wifly fixtures in the middle. Rig wouldn't respond, so I was going through the whole thing to find the bad cable... til I got to the wifly devices, and found that wireless was switched on. Turned wireless off, and suddenly everything works fine. So, there was some kind of conflict between the wired and wireless signal. With wifly on, it wants to rebroadcast that wireless signal.

Why even have a slave mode over wireless?? I guess if you were a dj, you could use one fixture in one of the auto-chase modes, and set the others around the room in Slave, sync-ed up with wifly? I wonder- if you gave the Slave a physical dmx connection to an addressed fixture, or set another fixture in one of those auto modes (gave it signal to listen to), if it wouldn't clear the channel for the other fixtures in DMX mode.
 
Between this forum, another one, and a good session at the theater this morning it all fell into place;
1/ Those little plug in 'receivers' aren't! They are both Rx and Tx. Without any input DMX on the wired side they receive. But if a signal appears on the wired side they transmit - and pulse red.
2/ When I looked the Canon it had somehow gotten out of DMX mode and into some Master mode thereby wanting to Tx to all around! This interfered with the main (real) transmitter so no other lights would work.
In retrospect it makes sense and today was a good day. I learned a lot. :)
 
No. I am using those little Donner dongles (which I subsequently learned can transmit if they sniff DMX coming in the wired port). The lamp causing the problem was a ADJ COB Canon which got accidently changed to a none DMX mode so it thought it was a "Master" and started Tx to its 'slaves'. The Dongle sensed this and transmitted thereby interfering with the real transmission so no 'real' commands got through to the others.
 
Just curious. I have some Show Babies going in on a project which do the same thing; transmit when the sense DMX in and receive when they don't. Do am told.
 
Once you're aware of the Tx/Rx thing and that some fixtures can broadcast their own little shows you're in a good position to solve any problems. If like us you use a lot of wireless DMX receiver, with some directly into the back of units on the floor (where movement can push cables against the 'menu' button!) our 1st action is look for the Rx pulsing red (Transmitting) and then putting the fixture back into DMX. Then, telling the lighting designer to keep their paws off them and ask us to make any movement or adjustment.
 
Just a minor terminology b!tch:

If the DMX jack can't generate its own signals, it should be labeled Thru, not Out, or such has been my experience of other such setups, both DMX and otherwise (MIDI, frex).

Out is reserved for signal *sources*, not things which can just pass through an In.
 
No. I am using those little Donner dongles (which I subsequently learned can transmit if they sniff DMX coming in the wired port). The lamp causing the problem was a ADJ COB Canon which got accidently changed to a none DMX mode so it thought it was a "Master" and started Tx to its 'slaves'. The Dongle sensed this and transmitted thereby interfering with the real transmission so no 'real' commands got through to the others.
That doesn't sound like a good feature.

I'd rather have a hard switch for TX/RX.
 
That doesn't sound like a good feature.

I'd rather have a hard switch for TX/RX.

I'd think they'd have to do some sort of switching on the fly to support RDP; at least, I can't think of any other way of accomplishing that, at least without doing a lot of complex packet sniffing and firewall-like activity that isn't especially easy to define and code precisely.

Setting the fixture to the non-DMX mode would equally well mess up a wired DMX system (or at least the segment up to the nearest splitter).
 

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