The DMX termination plug

[McCready00]

Is it still used in the industry? I just never seen someone using it so far. Is it because the news machines don't need it? If you are still using it... then when?

Thanks

[Wolf]

I still like to use them. Some people feel that the risk of corrupt information coming back up the line is very slim and dont feel it is necessary to use them. While the chance is slim the one time you dont use them is the time that something will happen and you may spend 20 mins trouble shooting instead of programing. Although some manufactures do have built in terminators so that is not necessary to use them (most boards have them).

[DaveySimps]

I still use them in all of my rigs. I also see them reguarly in touring productions with new gear.

~Dave

[church]

I always use them, the problems are most likely to occur at the end of a long termination and/or when you are approaching the 32 unit load. This is when the DMX signal is approaching its minimum signal parameters.

This is also why using an optically isolated DMX splitter improves the "reliability" of the command link - because it includes line drivers on the output you have the ability to drive another 32 units on each output.

[Kelite]

Originally Posted by McCready00

Is it still used in the industry? I just never seen someone using it so far. Is it because the news machines don't need it? If you are still using it... then when?

Thanks

When responding to Right Arm or Smart Color tech calls, a large percentage of DMX related misbehavior is traced to DMX termination (or lack of, in this case). Moving lights and color scroller PSU's rely upon a clean DMX signal though the entire run, and the longer the DMX run the more chance of reflection, as Church has pointed out.

DMX termination is very similar to car insurance. Sometimes you'll need the insurance when away from the system, and someone adds/subtracts/substitutes fixtures within your run. It seems rare that these changes are mentioned to the designer/TD/ME until a problem occurs...


This is a very valid observation, McCready00. I would stick with a DMX terminator at the end of each run.

[icewolf08]

You should always terminate your DMX lines as it is the proper way to run a DMX distribution system. I have seen plenty of unterminated DMX systems work fine, but at the same time you may not know if some internal motor is a fixtures is sitting there twitching because of reflected data. A terminator costs $5 and 5 minutes to build, so keep them in stock and use them, better safe than sorry.

[rmarston]

I agree - DMX was developed to be a very robust data buss based on EIA 485. But that buss was designed to be terminated with a 120 ohm resistor. It's a simple to add a terminator to each DMX buss to prevent the possibility of reflected data screwing up any fixtures.

Rick

[avkid]

Originally Posted by icewolf08

A terminator costs $5

You're paying too much for parts!

[zuixro]

Originally Posted by avkid

You're paying too much for parts!

Yeah, Mouser has the connectors for $2.68. The resistor is just a few cents.

[derekleffew]

See the Glossary entry: http://www.controlbooth.com/forums/g...ight=terminate.

Originally Posted by Wolf

... Although some manufactures do have built in terminators so that is not necessary to use them (most boards have them).

This is an absolutely UNTRUE statement. By definition, the control console or DMX source cannot terminate the line. Some dimmer racks and devices have a termination switch. I (and others) have yet to be shown a moving light or LED fixture that has "auto-termination" or "self-termination." I cannot recall ever seeing a fixture with a termination switch.

McCready00, you might find this poll useful: http://www.controlbooth.com/forums/l...ight=terminate. "DO as we say, not as we do."

Originally Posted by Kelite

When responding to Right Arm or Smart Color tech calls, a large percentage of DMX related misbehavior is traced to DMX termination (or lack of, in this case).

Kelite, your manuals need some revision. In previously researching this topic, I found that the RightArm manual does have a one-line remark (with an error!), but could not find any mention of 5-pin termination in the SmartColor manual. See this post: http://www.controlbooth.com/forums/w...tml#post103731.