terminators

[lazor]

Over time I have heard mixed opinions about the use of terminators. For the longest time I didn't use them and had no problems. I than got talked into buying some for our last musical and I didn't notice any difference.

Can someone clarify if and why they are important and am I just lucky that I had no problems in the past before the terminators were purchased?

Also, if I am daisy chaining a bunch of stuff together (Varilites, I-cues, etc.) and I end the chain with I-cues do I need to buy 4-pin terminators, and do they even make them?

 

[icewolf08]

Termination is included in the DMX 512A specification. Most of the time you can get away without termination, but you leave yourself open to issues. You won't necessarily notice a difference in the operation of your gear unless you are having issues that can usually be solved by adding a terminator.

If you are daisy chaining a bunch of devices ending in scrollers or icues, you don't need to terminate the 4 pin, as you are supposed to make a return loop back to the PSU which adds the termination. YOu do however have to add a terminator to the DMX thru port on the PSU.

 

[derekleffew]

lazor, just about everyone has mixed emotions/opinions about DMX termination, as this thread: http://www.controlbooth.com/forums/lighting/9116-dmx-termination-plug.html shows. See also: http://www.controlbooth.com/forums/lighting/6006-do-you-terminate-your-dmx-lines.html.

 

[lazor]

If you are daisy chaining a bunch of devices ending in scrollers or icues, you don't need to terminate the 4 pin, as you are supposed to make a return loop back to the PSU which adds the termination. YOu do however have to add a terminator to the DMX thru port on the PSU.

I didn't know that you were supposed to make a return loop. I will do that from now on.
But what do I do if I'm using a smaller power supply like the Rosco PSU-50w? All it has are one 5-pin male and one 4-pin female. There's no place to plug in a return loop?

 

[icewolf08]

I didn't know that you were supposed to make a return loop. I will do that from now on.
But what do I do if I'm using a smaller power supply like the Rosco PSU-50w? All it has are one 5-pin male and one 4-pin female. There's no place to plug in a return loop?

Well, I don't know how Rosco built the PSU, but the 5-pin and 4-pin circuits should be isolated form eachother (via optical chip). The 5 pin should be terminated in the PSU. Unless you run into issues with your Icues, then I wouldn't worry about terminating the 4-pin lines.

 

[JD]

Imagine the following two scenarios:
1) Drive 10 miles home from a club sober.
2) Drive 10 miles home from a club drunk as a skunk.

Now lets say you made it home both times safely. It didn't matter then, right? Well, the first drive was with terminators. The second drive was without. It won't matter until the day you have a problem, and then it may be too late.

The terminators keep the signal line clean by limiting trash data echoes and other noise. I almost always terminate. I have done a few shows where the system was up in the air, and I forgot to terminate. They worked fine, but given the option, I would always terminate.

 

[chieftfac]

I didn't believe in termination, until I borrowed some NSI dimmer packs and ran them out the 2nd universe on our 48/96 Express. Every time I altered a cue in tech rehearsal the whole rig would blink when recording the new look. A little termination fixed it, thus I could alter cue looks during preview and no one noticed... Termination is a good thing...