Ethernet - Why?

[Ben]

Rob,

interesting point well made, I will agree that its not always best to put in top spec, and we all dream of that venue where money is no object <_<

 

I'd argue with any suggestion that in a year's time we'll all be wanting to run everything on ethernet and throw out our DMX systems.

 

I would argue that too, we still use older systems than DMX512 so why should we stop using it when somthing else comes along? the point is that we may well need to upgrade to newer systems soon so why not install a system like ethernet now as more and more companies are starting to use it.

I do however see your point about leaving room in the trunking etc. and the cost of the upgrade being small as it is mainly just pulling cables, and that is somthing that I will do more in my future projects. ;)

 

Ben

[Grum]

The question

 

Would you prefer:

 

Option 1

 

An ethernet type system that requires extra boxes that convert one signal to another (like ethernet to DMX) thereby adding extra things to go wrong, and limiting the number of outlets that can be used at any one time.

 

Option 2

 

An installation that has ethernet outlets around your venue (seperate from any non lighting network) and at every ethernet point you also have a DMX point.

AND

A DMX patch bay in your control room (or anywhere you want it) that includes several splitters giving you the ability to use almost all of your DMX outlets at one time.

 

The rules

 

1. You cannot have option 2 with more than say 2 converter boxes (this allows desks that only output ethernet to output DMX thus keeping things fair)

 

2. You cannot have option 1 with a DMX network but no splitters or patch bay (this is because this is both impractical and would bring you over budget).

 

3. See rules 1 and 2.

 

Notes

 

Please bear in mind that the reason for asking this is because there usually isn't the money to have the situation in rule 1. especially without dropping the quantity or quality of other kit on the job.

Also think about the points already raised (integrity of the signal chain, future compatibility, what equipment you have available to you when one of the units dies (say the converter thats screwed to the wall in your dimmer room) 4 hours before your show, etc.)

Both options have the same number of points around your building.

At the end of the day these, in my experience, are the only two optins open without dropping the standard of the installation (something I won't do).

 

Answers on a postcard to.........

 

well.. here I guess.

[robloxley]

I'll go for Option 3:

 

An installation that has standard DMX outlets around the venue and a DMX patch bay in the control room (or anywhere you want it) that includes several splitters giving you the ability to use almost all of your DMX outlets at one time.

 

Why?: It allows us to use any lighting desk that spits out DMX (i.e. pretty much all), any dimmers that understand DMX (ditto) and any moving lights that talk DMX (ditto). Plus, because of the vast amount of DMX installs currently, you can bet that new equipment will be backward compatible and use existing cabling etc. (see Artistic Licence RDM as per Ian Ferguson's posts). It'll be the cheapest option - money saved might even be put aside for future upgrade as and when we know what else we are putting in.

 

My only caveat might be that if today you, say, wanted a remote video node in the stalls for plotting sessions on your 520, or the ability to run multiple desks or servers, you would probably go for some kind of cat5 backbone to run this on. But as for speculatively running cat5 around the stage area for potential future use, at this stage, I would rather spend the money elsewhere.

[Andrew C]

Just a thought, and I’ve not looked at the tables or anything yet, but I suppose that DMX could be distributed over a structured data system. <_< (Hides in dark corner expecting brickbats) You’d need to check voltage drop on the thinner cores of CAT5 STP cables and that twist rates and screening were appropriate.

 

It may be that a DMX distribution amp would be needed at the remote end from the desk to boost levels if there are drops, rather than a simple daisy chain.

 

For a small increase in price on the original install you could benefit from a very flexible infrastructure. UTP = £109/305m, STP = £119/305m. I can’t see any indication on patch panels as to whether they’re screened or not so no price comparison is possible.

 

Some klutz from marketing could theoretically unplug your DMX and try to print next year's brochure on the dimmers, but only if planning is poor.

 

So, DMX now, TCP when and if you need it & networked “Unreal Tournament†™ during those really dull scenes.

 

Andrew

 

BTW. I’ve used an unscreened panel for patching a rack of videos, satellite receivers and the like together with perfectly acceptable results. MUCH cheaper than MUSA, carries audio & vid on one cable!

[Grum]

Andrew,

 

Several companies use CAT5 cable for DMX installs already (and rearly have any problems) this means you can run two streams down one cable (not a good idea to run a send and return down the same cable though).

And surely your nosey marketing type wouldn't be able to get anything from his computer to go to your dimmers because they'd be on seperate networks wouldn't they?? or would you risk loosing control of your dimmers because someone in marketing changer the IP address on thier computer.

 

Rob,

 

what you described is what I meant in 2, the extra cost in running e-net to every DMX point is so small that on most jobs you wouldn't notice (if your running one cable from A to B its not much harder to run two especially if they are both CAT5) the cost saving would be lost when you find out that the guys that did the cable pulling screwed up and they have to re do some (or worse all) of it.