DMX Present Contactor

Two of the eDIN interface modules - the #1003 Contact Closure and the #1008 LED Dimmer/DC Driver - have a DMX present relay. It is a single pole double throw relay which can be wired as either Normally Open (NO) or Normally Closed (NC). When wired as Normally Open, the relay closes when valid DMX is detected on the DMX IN. Closing a relay on the simple presence of DMX, versus triggering a relay at a specific DMX value (which is the purpose of the #1003 card) offers some creative benefits. Here are just two examples of how to use this feature.


This example uses a simple indicator light to show whether the console is on or not. This might be a useful thing to have on the stage manager’s panel so when you start your call you can see if someone has already visited the booth. LED indicator lights are tied to the eDIN power supply that runs through the DMX Present relay. When the 1003 detects active DMX, it throws the relay and illuminates the On LED (and the Off LED goes out).

You may also want to feed the Commons of all the relays through the DMX Present relay if you want to make sure that none of your devices will operate when there is no DMX. Do not exceed the 2A at 30VDC rating of this relay.


In this riser, the LED power supplies will not be energized until there is console feeding valid DMX to the system. In some jurisdictions, you cannot have the phantom loads of switching power supplies present even if the lights are told to go to 0% intensity.