DMX Decoder

Robert F Jarvis

Active Member
Joined
Apr 8, 2017
Location
Sebring, FL, USA
I use a couple of boxes that when addressed initiate some relays. But they require a DMX address for each relay (e.g. one for Red, One for Green and so on). I'm looking for a box or system (Raspberry Pi. Arduino perhaps) where I can Decode the data being sent to a single DMX address and have that presented to 8 pins for actuating my relay system. So, if I send "16" to that address then pin 4 will go high (or low). Are there any commercial units that would do this?
 

Crisp image

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Joined
Jun 18, 2017
Location
Eastern Victoria Australia
I use a couple of boxes that when addressed initiate some relays. But they require a DMX address for each relay (e.g. one for Red, One for Green and so on). I'm looking for a box or system (Raspberry Pi. Arduino perhaps) where I can Decode the data being sent to a single DMX address and have that presented to 8 pins for actuating my relay system. So, if I send "16" to that address then pin 4 will go high (or low). Are there any commercial units that would do this?
I am not sure what you are asking here. The DMX relays I have used are a 3 address with 3 relays. starting address might be 101 then it would use 102 and 103 for the 3 relays. Any dmx signal over half activates the relay and closes the contacts.
If that is what you want then all good but if you want a single address (say 101) to control a relay board with multiple relays connected to a Raspberry Pi then as far as I know you are out of luck.
Someone may be able to write some code so DMX value 50 is relay one ,100 is relay 2 150 is relay 3 and so on and that could be on the one address but as you go through the DMX values all of the relays come on in sequence which is fine if that is what you want but if you wanted to skip one relay it might not be possible.

My thoughts and no one elses.
Regards
Geoff
 
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Robert F Jarvis

Active Member
Joined
Apr 8, 2017
Location
Sebring, FL, USA
Ron
I too use a number of 12volt relays. But as we both noted each relay requires a separate DMX address. In my junk box is a Bitwizard DMX board used eons ago that interfaces directly on top of the Raspberry Pi but the only code I have is to - again - use one DMX address per out. My hope was that someone made a device with a single address which you could program so that the incoming 8 bits could be translated like "1 > 10 put pin 1 hi. 11 >2 0 pin 2" etc. But thinking about it my own request, it really looks like I should spend some time and hack out code for the Pi.
 

MRW Lights

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Jan 4, 2017
Location
NYC
The only issue I see with the programming for a single dmx address is that you'd have to move through values to get to your needed value and you wouldn't be able to hold control on more than one pin at a time. If you were looking for Pin 3 you'd have to move through pins 1-2 to get there...

The curious dmx cat has to ask... whatchya doing? :think:
 

RonHebbard

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Premium Member
Joined
Jun 12, 2004
Location
Waterdown, ON, CA
Ron
I too use a number of 12 volt relays. But as we both noted, each relay requires a separate DMX address. In my junk box is a Bitwizard DMX board used eons ago that interfaces directly on top of the Raspberry Pi but the only code I have is to - again - use one DMX address per out. My hope was that someone made a device with a single address which could be programmed so that the incoming 8 bits could be translated like: "1 > 10 put pin 1 hi. 11 >20 pin 2" etc. Thinking about my own request, it really looks like I should spend more time and hack out code for the Pi.
@Robert F Jarvis , which "Ron" are you referring to, if you're referring to @RonHebbard , I'm afraid I have no idea which of my posts you're referencing??
Toodleoo!
Ron Hebbard
 

DrewE

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Joined
Mar 18, 2019
Location
Vermont
The only issue I see with the programming for a single dmx address is that you'd have to move through values to get to your needed value and you wouldn't be able to hold control on more than one pin at a time. If you were looking for Pin 3 you'd have to move through pins 1-2 to get there...
I'm pretty sure he's looking for a binary decoding, not a 1 of N decoding. Like thus:
DMX Relays
000 : 00000000
001 : 00000001
002 : 00000010
003 : 00000011
004 : 00000100
005 : 00000101
. . . . . . .
254 : 11111110
255 : 11111111

It would be very straightforward and inexpensive to implement using a modern little microcontroller of some sort. I don't know of any off-the-shelf solution offhand, though.

Obviously when using this one would want to studiously avoid fades or manual fader control or 0-100% levels on the relay channels from the lighting console, and either be pretty good at binary to decimal conversion or have a lookup table handy for setting the right ones on and off. It's trading a lot of convenience in operation for one-eighth the DMX512 channel usage; I'm not sure that's a particularly wise tradeoff in most circumstances.
 

Robert F Jarvis

Active Member
Joined
Apr 8, 2017
Location
Sebring, FL, USA
I'm afraid not. I use this one regularly - you toggle a base address and any valid data on that address and the subsequent seven will activate on of the relays (I also use a 16 channel one). See previous posts. My needs are for a single DMX address that has its data decoded to toggle different relays. Hence my plan to use a Bitwizard on top of a Raspberry Pi to set it pins which in turn will flip the relays. I can hold the pin state .
 

almorton

Active Member
Joined
Dec 17, 2014
Location
Caterham, Surrey, UK
And yet plenty of answers were offered for the same question asked by the same OP on there, and also for the LV signs query. Plenty of participants from around the world, although it does have a tilt towards the UK.

Have you been back to see if the replies on BR were useful, Robert? BR doesn't notify you by email unless you ask it to, so it may appear as if nobody has replied if you're waiting for notification.
 
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