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DMX in high channel counts

Started by zwiller, January 19, 2016, 09:11:04 AM

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zwiller

I have not seen a discussion of using DMX in higher channel counts.  IE DMX at say channel 12,345.  For some reason I recall the DMX universe is limited to 512 channels and that the data is repeated, so as long as I have have controller set for the appropriate "512th universe channel" I am good to go? 
Sam

gadgetsmith

You can specify in xlights and/or FPP a USB dmx dongle output, starting at channel 12,345 and going for up to 512 channels.  The connected dmx controller will only see channel 1 thru 512, and know nothing of it's global 12,345 start channel.

tbone321

Quote from: zwiller on January 19, 2016, 09:11:04 AM
I have not seen a discussion of using DMX in higher channel counts.  IE DMX at say channel 12,345.  For some reason I recall the DMX universe is limited to 512 channels and that the data is repeated, so as long as I have have controller set for the appropriate "512th universe channel" I am good to go?

In a way, that is correct.  The only issue is where that particular channel winds up and that depends on how you define your universes. 

zwiller

Thank guys.  Getting there...  So say I run FPP to F16v2.  I send 1.31 which also sends DMX, right?  I've got 3 dmxouts on F16V2.  I can set them up however I want?  IE I set first DMX out to channel 12,345 and device to DMX channel 1.  DMX output from that device continues 12,345 to another 512 and ends or does it keep going?  Still a little lost on best way to setup/run layout with this concept in mind. 
Sam

gadgetsmith

Quote from: zwiller on January 20, 2016, 09:34:45 AM
Thank guys.  Getting there...  So say I run FPP to F16v2.  I send 1.31 which also sends DMX, right?  I've got 3 dmxouts on F16V2.  I can set them up however I want?  IE I set first DMX out to channel 12,345 and device to DMX channel 1.  DMX output from that device continues 12,345 to another 512 and ends or does it keep going?  Still a little lost on best way to setup/run layout with this concept in mind.

If you're sending DMX out of the F16v2, then you're just sending E1.31 from the FPP.  The F16v2 Serial Outputs screen is where you will determine what incoming E1.31 channels get sent out as DMX.  It will only send 512 Channels from whatever start channel you set.  Typically i'd set aside an entire universe for DMX control inside xLights (or whatever sequencer software you like to use), so when you get to the F16v2 setup, you just specify the start channel (Universe/Start or Global addressing) and it coincides with the channels in your sequence software.

What sort of DMX props are you running?  How many?


tbone321

Quote from: zwiller on January 20, 2016, 09:34:45 AM
Thank guys.  Getting there...  So say I run FPP to F16v2.  I send 1.31 which also sends DMX, right?  I've got 3 dmxouts on F16V2.  I can set them up however I want?  IE I set first DMX out to channel 12,345 and device to DMX channel 1.  DMX output from that device continues 12,345 to another 512 and ends or does it keep going?  Still a little lost on best way to setup/run layout with this concept in mind.

Actually, E1.31 is DMX as in DMX over Ethernet.  Don't get hung up on the DMX thing.  As far as the sequencer goes, a channel is just a channel and that's how you should think of it as well.  Where it counts is at the controller level.  Each port on a controller is only capable of delivering one protocol at a time.  If you configure your F16v2 to output DMX on one of its ports, then it will deliver DMX (up to 512 channels) on that port.  If it is the only port on the controller configured to output DMX, then it will be the only one putting out DMX.  If you define 3 of them for that, then you will get up to 3 universes of DMX with one on each configured port.  As for the channels you are getting, that is up to how you define them. 

If you want channel 12,345 as the first DMX channel on port 3 of your controller, then Pick a universe in FPP's E1.31 configuration and start it at channel 12,345.  If you want the full DMX universe then set the length to 512 and if you need or want it smaller, that set the length lower.  Either way, channel 12,345 will be the first DMX channel in that universe.  On the controller side, set port 3 to the universe number that you defined it to be in and sequencer channel 12,345 will be there as channel one.  In most controllers you can also set the length or the end channel for that port so if set to 512, then it will continue on for the full 512 channels but it is NOT required to do that.  If you want other ports to output DMX, then just define universes in FPP that contain the channels that you want to be in DMX format and assign those universes to the desired ports on the controller(s) that you want to output them and configure them for DMX output.  Your DMX universes do not need to be contiguous in the channel numbers and they shouldn't need to be 512 in length either.

AussiePhil

Just to add to the last post.

Regardless of the number of channels you are going to use if your going to need an actual DMX stream it is far easier to deal with it as a 512ch block or multiple 512ch blocks if needed.
Do this at all points, Sequencer, just allocate a 512ch block, fpp - send that 512ch block out as a full universe, controller - send all 512ch out.
Your endpoint dmx devices will just use the channels they are set for.


gadgetsmith

The F16v2 controller will send 512 channels regardless of how sequencer or FPP is setup.  Controller just grabs 512 contiguous channels from the start channel and sends them.  This is because some DMX controllers expect (and rightfully so) a full 512 channels.

My setup includes 10 universes, Universe 1-10, reserved for Renard, DMX and wireless stuff. I only set 510 channel universes, so when F16v2 sends DMX, it sends 2 channels that might be dedicated to something else, but it doesn't really matter, as I'm only using maybe using 30 or so of the 512 channels sent, everything else will be ignored.

tbone321

Quote from: gadgetsmith on January 21, 2016, 06:18:24 AM
The F16v2 controller will send 512 channels regardless of how sequencer or FPP is setup.  Controller just grabs 512 contiguous channels from the start channel and sends them.  This is because some DMX controllers expect (and rightfully so) a full 512 channels.

My setup includes 10 universes, Universe 1-10, reserved for Renard, DMX and wireless stuff. I only set 510 channel universes, so when F16v2 sends DMX, it sends 2 channels that might be dedicated to something else, but it doesn't really matter, as I'm only using maybe using 30 or so of the 512 channels sent, everything else will be ignored.

If this is really how the F16v2 works, then that seems to be a very poor implementation of E1.31 and even DMX 512 for that matter.

gadgetsmith

Quote from: tbone321 on January 21, 2016, 07:36:57 AM
Quote from: gadgetsmith on January 21, 2016, 06:18:24 AM
The F16v2 controller will send 512 channels regardless of how sequencer or FPP is setup.  Controller just grabs 512 contiguous channels from the start channel and sends them.  This is because some DMX controllers expect (and rightfully so) a full 512 channels.

My setup includes 10 universes, Universe 1-10, reserved for Renard, DMX and wireless stuff. I only set 510 channel universes, so when F16v2 sends DMX, it sends 2 channels that might be dedicated to something else, but it doesn't really matter, as I'm only using maybe using 30 or so of the 512 channels sent, everything else will be ignored.

If this is really how the F16v2 works, then that seems to be a very poor implementation of E1.31 and even DMX 512 for that matter.

This is what I read about DMX on the F16v2.
http://falconchristmas.com/forum/index.php/topic,3496.0.html

I'm no expert of DMX or E1.31, so not sure what makes it a bad implementation.  Isn't E1.31 just a "wrapper" for a DMX packet such that it can be handled on standard networking equipment?  As far as DMX, I think any DMX controller just needs to be considered Universe 1/Channel 1 on any of the 4 outputs available?  The F16v2 handles which sequenced channel is sent to that controller, or at least that was my understanding, which may in fact be wrong.  I tested DMX by setting up 30 channels (10 RGB floods), but only actually ran 9 channels (3 floods).  I thought I was sending on universe 101, but it might have been universe 1 as I tested this a while ago and can't seem to find an xlights setup for it anymore.

tbone321

It is a poor implementation because there is NO requirement for a DMX 512 universe to always be 512 channels.  It clearly says up to 512 channels and DMX 512 is a robust protocol so there are plenty of indicators for end of packet regardless of length.  But even if it is easier or more consistent to always output 512 channels in the DMX output, it really shouldn't blindly pull data to fill that need, especially from other universes.  Sure, when you are dealing with pixel strings which can go way above 512 channels, you need to combine universes and even start somewhere in the middle of a universe at times but this is a bad idea when dealing with DMX 512 which can always fit in a single universe.  As you said, E1.31 is DMX over Ethernet so if you define a controller to output DMX, then all it should get is the universe number to use.  If you are going to allow for variable length DMX output, then also allow to specify the size up to a max of 512.  If your defined or fixed length is larger than the selected universe, the remaining output channels should simply be zeroed out.  This will prevent confusing or unexpected output.  Don't get me wrong, this is not an attack on the hard work that Dave or anyone else has done to make this awesome equipment available for us but if nobody ever has an opinion that differs from what it currently is .....

taybrynn

It sounds more flexible than the standard to me ...

zwiller

I was following this pretty good until now  ;D  I think it is clear that I should clear out first 512 channels of PN and dedicate this to dmx controllers IF I go that way.  Still unsure.  2811 floods will help alot but strobes are up in air at this point. 

Sam

gadgetsmith

Quote from: zwiller on January 21, 2016, 01:32:46 PM
I was following this pretty good until now  ;D  I think it is clear that I should clear out first 512 channels of PN and dedicate this to dmx controllers IF I go that way.  Still unsure.  2811 floods will help alot but strobes are up in air at this point.

Perfect!  :)

... as always though, the discussion is always more interesting than the answer! I think ?  B)

pixelpuppy

Quote from: tbone321 on January 21, 2016, 12:22:40 PM
It is a poor implementation because there is NO requirement for a DMX 512 universe to always be 512 channels.
The SanDevices controllers do the same thing.  If you set an output to DMX it will always output a full 512 slots regardless of what  you set the pixel count to be on that port.  I remember reading some time back that Jim St.John specifically added this to the firmware because of problems with DMX devices that didn't work properly if the DMX frame was not a full 512 slots.

I agree that the DMX protocol does not require a full 512 slots for every frame.  BUT it seems there are devices that are expecting it.  So if there is a "poor implementation" its THOSE devices.  These controllers do it to overcome that limitation in those devices. 

I do not know how the AlphaPix and PixLite controllers handle it.

Quote from: zwiller on January 21, 2016, 01:32:46 PM
I was following this pretty good until now  ;D  I think it is clear that I should clear out first 512 channels of PN and dedicate this to dmx controllers IF I go that way.  Still unsure.  2811 floods will help alot but strobes are up in air at this point. 
Don't let this complicate things for you. ;)  Nothing wrong your idea and its probably easier in our heads that way.  But I think the F16V2 controller handles DMX really well and it doesn't care what channels we use for DMX.  It allows us to map any absolute channel to any DMX output channel.

I use the DMX output on all of my F16V2 controllers and it was very easy and had no problems at all.
-Mark

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