DMX terminator WIKI

[prodigal2]

Hi there one and all.

 

I just had a look through the BR Wiki (shows signs of becoming of being a great resource) and glanced across the page on DMX terminator and felt that something needed commenting upon:

 

“DMX circuits should always be terminated”

 

Though this is technically correct, it doesn't quite pan out like that on a gig, it is usually better to use a terminator to rectify a problem that may be manifesting its self.

 

The item that should always be used is, a opto isolated buffer with a big fistful of terminators if you need them. Why I hear you mumble, well for 3 very important reasons:

 

1) to protect the desk from voltage leakage onto the DMX lines, taking out the processor on the desk (has happened to me once during a show, not fun!!!!!)

 

2) to refresh the signal strength, even the voltage drop over 50m can make the difference to some older racks seeing and not seeing DMX.

 

3) simple and short DMX runs, making fault finding quick. By simple I mean as a rule a DMX line having no more than 8-10 units on it, and they should be all of the same manufacturer, as this can add to your woes mixing flavours of fixtures (high end being a good one NOT to mix with anything else). This is important for DMX fault finding, as a fault will be found and fixed within 30 mins, whereas if you run 32 fixtures on one line the fault will take hours to find and may take up most of the crew to locate. And more importantly reduce programming time or worse still, hold the doors to open the show.

 

 

 

Number 3 is what makes the difference on site day to day, as it means programming wont get held up, and if a line goes down during a show you dont loose a whole rig.

 

 

I apologise if this is not technically correct, all I can say is this system sticks to the KISS rule, sadly some crew can't get their heads around it during plug up, when there is clear paperwork, reinforcing my view on why I do design my DMX systems thus.

 

Great forum by the way

 

Phil Haynes

[merlin24]

DMX Lines do not always need terminating, it works on a case by case scenario, it is a good idea to terminate but this will on occaisions actually cause issues.

 

Regards

Andy.

[bruce]

C'mon chaps - saying "DMX lines do not always need terminating" is a bit like saying "You don't always need to look right and left before crossing the road". You might get away with it most of the time, but eventually you'll get knocked over.

 

And the busier the road, the more likely you are to come to grief. hey - this is turning into a really good analogy.

 

Whether it's a "good idea" to terminate is irrelevent - the standard says that you must. We've been here so many times before, I suggest we close this discussion now.