DM0 – Question on what is stored on the unit itself

[glparke]

Good morning. Running a DM0 engine with only IP8’s and director. Just curious as to what information and data is actually stored on the DM0 itself? Is it audio position and levels only? or are scenes and fader “layout” for director and channel names stored there? Curious as to what is “brought down” when I connect to the DM0 from direct and tell it to pull from the unit instead of pushing to it.

Thanks for any help
Gary

[Dave]

My understanding — and to the best of my recollection this is just supposition based on my own knowledge of how computers work and not anything official — the MixRack doesn’t “store” anything other than the state of all the buttons, knobs, and faders. This is why (and again, IIRC this is my supposition, not fact) you can just kill power to a MixRack but you need to shutdown a surface. A surface is a full computer (you can see its BIOS screen if you have an external monitor hooked up) and has show files, scenes, user libraries and whatnot that are all stored in various files, and, as we all know, just pulling the plug on a PC can sometimes result in data corruption if the system was in the middle of writing a file. The MixRack probably just stores the current settings in some tiny amount of non-volatile memory that’s hardwired to the FPGA, so there’s probably no file to save when you change at setting or load when you turn it on — the data’s already in memory when the FPGA goes looking for it. They can do that because all these values like compressor thresholds and toggles and knob positions can be manipulated with what’s called “atomic” operations. That is, there’s no intermediate state when you change a value*… if you unbypass a compressor, one moment the system says a compressor is bypassed and the next moment it’s not. Saving a scene, though, there’s tons of values that need to be written for that and, at least as far as computer processors are concerned, it takes a while and the data in the scene probably won’t be valid until it’s done.

*The exception to this is the names of all the channels and busses and stuff. Changing those would normally be non-atomic, but you can make it atomic by having a bit more than twice as much storage as you need. In this case, 16 characters for the name instead of 8, plus a flag to tell the system whether to use the first or second half of the storage. Changing the value of the flag is atomic, so if you lose power while renaming a channel from “Patrick” to “Sarah”, when you turn it back on the channel might be “Patrick” or “Sarah” depending on exactly when the power went out, but under no circumstances will the channel be “Sarrick”.

[glparke]

Thanks Dave, that is what I was thinking, BUT – using just an Ipad and the DM0, my Ipad shows all my scenes. You can recall but not store. I think that is new though for 2.0.

[Dave]

Oh? Hmm… was Director running last time your iPad was connected? Could it have gotten the info that way? Hmm… but then what would happen if Director was running and a surface was connected? Which would it pull scenes from? Maybe some of that stuff’s stored on the MixRack after all.

[msteel]

I did not find an authoritative answer to this, but here is what I think:

* Anything that pertains to the Mix Engine lives on the Mix Rack. This includes channel names, colors, routing. processing, FX, I/O patching, Ganging. Before v2.0, MIDI commands could only target a Mix Rack, so it is a pretty safe conclusion that anything that could be changed by a pre-2.0 MIDI command actually lived on the Mix Rack.

* Things like strip layout, soft keys, custom rotary settings, etc. belong to the surface and are stored there. Also, show files and cue lists live on a Surface.

* I am not sure about preamp settings – I suspect they are stored in the Mix Rack. Except, it may be that they are stored on the component where they are physically located. For example, Preamp settings for a Socket that is located on a Surface cannot be changed by another Surface in a multi-surface configuration. I am not sure if that is because the settings live on the Surface, or if the other surfaces just don’t know what component to ask/tell.

* IP Controllers can connect to either the Mix Rack or a Surface. I think those settings are saved with the component to which they connect.

* Scenes have a split personality. The Mix Rack has its 500 scene slots, and each Surface has its own 500 scene slots. When a scene is stored, each component stores its parameters to its own scene data. When a scene is recalled, each component recalls its data. I think scene naming is communicated between the components so that each component has a copy of a scene name.

So, when your iPad was seeing all your scene data, it was communicating with the Mix Rack and pulling the scene names from it.

[glparke]

Thanks msteel and Dave. I did not have the Ipad connected while director was up and running. Just tried it again and with direcotr and the ipad app off, I loaded up the ipad app and connected and scenes were there so confirming the scenes getting pulled from the DM0, which is pretty cool. opens up some options with that and having to have director up and running to just recall scenes.

[Julian Tinao]

My understanding is:

Actual state of the mixrack and all Scenes are stored in mixrack.
Shows list is stored on Surface, AND in Director, each having his own list of shows.
Preamp data, is part of the actual state of the mixrack stored in the mixrack, BUT it is easy to have preamp state “not recalled” because of safes, and every external preamp remembers its settings, so, if the mixrack is not pusshing its settings inte the preamp, you could bring the preamp settings into your scene.

When you connect Director it will ask if you want to connect to “mixrack” or “mixrack and surface”, if you connect just mixrack, you will have an idependent fader layout and could configure an independent PFL, basically like having another virtual surface. If you connect “mixrack and surface” the fader layout of the surface will be mirrored on Director, and Director will be like another control for the real surface.

The actual state of the mixrack is handled in real time in a volatile memory in the mixrack. After 60secs (something like that if I remember well) the mixrack state is stored to non volatile memory inside mixrack. That means, if you disconnect the surface, everything will be there when you reconnect. If mixrack loss power, the “last state” will be recalled with kind of 60 secs of uncertainty.

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