DMX Generator

[Bruff]

I'm looking for a standalone device which will output 4 channels of DMX data, i.e. a static scene of 4 channels.

The innards of a cheap 6-way desk with the faders replaced with presets would do the job, except for the fact that I need 8 of these, all with different start addresses, and the 6-way controllers all start at 1, of course.

The closest I've found is the Milford Instruments 1-553, serial to DMX transmitter, but it seems like a bit of a sledgehammer to crack a nut.

 

Any ideas?

 

Steve

[Brian]

Have a look at the Showtec Scene Pilot.

[timsabre]

This would be a simple job for an arduino - there's plenty of examples of DMX software.

[the kid]

Would something like this http://www.greenwichinst.com/products/GWDMX do ?

 

I was looking in to them but never got to buying them.

[Bruff]

Three excellent suggestions - thank you.

The GWDMX and the Scene Pilot might be a bit pricey, but have the advantage of being plug & play, so they'd save time, which is a significant cost. I'm tempted by the Arduino, if only because it's been a long time since I played with anything like that and I think I might enjoy it!

Thanks,

Steve.

[boatman]

Just out of interest, why do you need them to start at different addresses? Are you going to merge the outputs into a single stream?

[Bruff]

OK,the bigger picture:

 

There is an area of our building which is lit by compact fluorescent up/down lighters. We often colour these for corporate events, which involves taping gel around the lamps - inelegant and time-consuming. I'm going to convert these to LED fixtures, controlled via wireless DMX (the existing wiring is effectively inaccessible, and the building is listed). I want each element (up & down) of each fixture individually controllable, so they will therefore all need be addressed differently.

 

Now the interesting bit - some of these fixtures are on the emergency lighting supply (maintained, static inverter, 230V). In the event of a mains failure, these must not only remain lit, but revert to full open white. So, my thinking so far is to have the DMX feed to each lamp routed through a changeover DMX relay, held closed by a "pilot" DMX channel. In the event of loss of transmitted DMX, the relay would change over to the locally-generated DMX and the fixtures would thus revert to o/w.

 

The main control system and DMX wireless transmitter would take their mains from the live side of the switch feeding the area, thereby providing the pilot feed.

[smalljoshua]

Is there not a requirement for the Maintained Emergency Lighting system to comply with BS5266 - Emergency lighting Code of practice for the emergency escape lighting of premises?

 

Would your proposed system comply with this?

 

Josh

[timsabre]

Josh is right, it was all sounding good until you mentioned the emergency lighting.

 

I am sure that unfortunately your insurance company will be very much against this unless you can produce test certification for your modified fixtures.

 

Could you maybe install some conventional emergency fittings in addition?

[Jivemaster]

Remember also that you say that your venue is listed, Your listing documents and your premises licence will impose conditions on what you can do, everyone will want BS numbers for everything that you use.

 

Note also that the USITT spec of DMX forbids using the protocol for safety critical applications, and I would consider control of emergency lighting to be safety critical.

[Don Allen]

What about using a control system such as X10 to use the existing mains wiring to get your control to an RGB flouro tube.

[dbuckley]

The control in that newer radio controlled LED fixtures are vastly superior to what one could do with X10.

 

For most of your lights, the use of wireless controlled LEDs looks workable. The issue is the emergency fixtures.

 

My terrible solution, given wiring is an issue, would be to have non-maintained "ordinary" emergency light fixtures with internal batteries installed adjacent to the next uplighters along, so that when the power fails they come on. The LEDs on the static backup can then be jury rigged as you suggest to give additional light, but it is the off-the-shelf approved emergency fittings that enable compliance with the regulations.

 

In terms of jury rigging, what I'd do would be to have the relays held closed by mains, so mains failure would cause the relays to open, and have the backup DMX feed on the NC contacts. Obviously the backup DMX feed and the transmitter(s) will need UPS power :)

[Bruff]

The area is covered by alternative, non-maintained secondary lighting. The fittings I'm intending to modify aren't part of the normal secondary lighting system, and aren't switched on for our annual inspection (I think they were connected to the secondary supply as a matter of convenience for the installation contractors; either that or the design changed subsequently).

 

My desire to have them turn o/w on mains fail is additional safety - "we're not in party mode any more, people..."

 

 

 

what I'd do would be to have the relays held closed by mains, so mains failure would cause the relays to open, and have the backup DMX feed on the NC contacts. Obviously the backup DMX feed and the transmitter(s) will need UPS power :)

 

The only mains into the fittings is the secondary feed, so can't be used to sense mains failure.

 

Main DMX (possibly coloured, dim, or off) will be on the n/o contacts; backup DMX (100% o/w) on the n/c. Relay held closed on reception of main DMX; failure of main DMX opens relay switching to backup. Main DMX feed and transmitter therefore must not have UPS, and be fed from the live side of the switch controlling the lights in that area.

[timsabre]

The only mains into the fittings is the secondary feed, so can't be used to sense mains failure.

 

??

Surely the secondary feed would go off in the event of mains fail... that's how emergency lights work.

 

How do you know that your "pilot DMX" would go away in the event of an emergency?

[dbuckley]

Bruff, either you or I have misunderstood :)

 

The only mains into the fittings is the secondary feed, so can't be used to sense mains failure.

 

I was suggesting the the mains powered relay is in the feed to the wireless DMX transmitter, which presumably is not adjacent to the lights...? And is powered from wherever the lights get their mains from. So if the mains fails to the lights generally, then the relay opens, and the UPS powered lights change from colour to o/w.