Fixtures that support RDM?

[dgaller]

Hi all, new to RDM and had a few questions:

1. I understand the DMX controller/engine needs to support RDM, but does the fixture?
2. Are there ways of taking a standard fixture and "upgrading" it to support RDM, or would that need to be done in silicon?

I have a 24ch 24v DMX decoder I'm using to control several LED light strips. However, I would like to utilize the RDM functionality of the decoder (which it does have), but I cannot find any LED strip lighting that explicitly has RDM support. Is that because ONLY the engine needs to support it? Thanks for any help.

[sblair]

Welcome!

Both ends have to support RDM. You have to have support for it in both the controller and in the device for it to work. Additionally, if you have any DMX Splitters in-line they also have to have RDM support as well.

There really isn't any easy way to add RDM to a device that doesn't support it. Wybron used to make a product called the "Dog Bone" that was basically a small microprocessor that plugged into a socket in place of commonly used RS485 receiver chips to add limited RDM functionality. Wybron went out of business though and I'm not sure of anyone else making anything similar.

RDM doesn't require any special hardware for a fixture, it just requires support for it in the firmware. The best thing to do is always to let manufacturers know that RDM-support is a factor in your purchasing decisions.

In your specific case, you've got a DMX decoder that does support RDM, so presumably that would let you set starting address and maybe a few other parameters. But, that is just converting the DMX signal to 0-24V to drive the LED strips. There really is no intelligence beyond the output of the DMX decoder since it is just analog drive. All the intelligence is located in the DMX decoder which is where the RDM support is actually needed. There is no logic or intelligence in the analog LED strips that you would be able to get any info back from anyway.

[dgaller]

Originally Posted by sblair

Welcome!

In your specific case, you've got a DMX decoder that does support RDM, so presumably that would let you set starting address and maybe a few other parameters. But, that is just converting the DMX signal to 0-24V to drive the LED strips. There really is no intelligence beyond the output of the DMX decoder since it is just analog drive. All the intelligence is located in the DMX decoder which is where the RDM support is actually needed. There is no logic or intelligence in the analog LED strips that you would be able to get any info back from anyway.

Aha, so basically the DECODER reports the status of itself back to the ENGINE. BUT, if the decoder sends its PWM signals out the "analog" side (12v/24v), the fixture attached on the analog side obviously cannot report what it's doing since it's just regulating power to change colors, is that correct?

If that's the case, how can RDM report what it's doing if it really doesn't know how well the fixture is responding? For example, wouldn't it report inaccurate information if, say, there IS no fixture attached to the decoder?

[sblair]

Originally Posted by dgaller

Aha, so basically the DECODER reports the status of itself back to the ENGINE. BUT, if the decoder sends its PWM signals out the "analog" side (12v/24v), the fixture attached on the analog side obviously cannot report what it's doing since it's just regulating power to change colors, is that correct?

If that's the case, how can RDM report what it's doing if it really doesn't know how well the fixture is responding? For example, wouldn't it report inaccurate information if, say, there IS no fixture attached to the decoder?

Correct, the decoder reports the status/configuration of itself back to the Controller. The decoder has no knowledge of what is actually connected to its PWM outputs as you said since it is just regulating power.

Most of the time we are talking about a complete product like a moving light, smoke machine, or LED fixture that is fully integrated and has full knowledge of all it's sensors and properties to report back via RDM. In this case you're building something by connecting two different products together so you're capabilities in RDM are limited to what the Decoder can provide.

[dgaller]

Originally Posted by sblair

Correct, the decoder reports the status/configuration of itself back to the Controller. The decoder has no knowledge of what is actually connected to its PWM outputs as you said since it is just regulating power.

Most of the time we are talking about a complete product like a moving light, smoke machine, or LED fixture that is fully integrated and has full knowledge of all it's sensors and properties to report back via RDM. In this case you're building something by connecting two different products together so you're capabilities in RDM are limited to what the Decoder can provide.

Got it, thanks so much for the info!