Case Study: 0-10V Dimming
As part of a recent audio and lighting system installation project at the Town Of Islip - Town Hall Annex Theatre, WiredUP was tasked with integrating the In-ceiling LED panel lighting with an already-designed DMX control system. With all modifications post system design, WiredUP will work with the customer and other trades to overcome the difficulties presented. This situation was no different.
The control premise of most LED in-ceiling panel lighting is an analog 2-wire 0-10 Volt dimmer. WiredUP system designers immediately turned to Doug Fleenor Designs for their DMX512-ANL-TB DMX to Analog 0-10V converter. The product features a data input for DMX512 protocol, and has 12 channels of 0-10V dimming on the output side. But this design also featured an unexpected flaw. Even when at the lowest dimming point, LED panel lighting is still illuminated to 10% brightness. In order for the lights to be completely off, one of a few things needs to happen. Either, line voltage to the fixtures needs to be removed when the fixtures are desired to be completely un-illuminated, or, a relay pack, usually made by the same manufacturer as the fixture, needs to internally reverse the polarity of the 0-10V signal. In simpler terms, just reversing which leg is receiving positive voltage.
With this fact in mind, engineers bench tested the theory of using an additional channel output from the DMX512-ANL to power the negative leg when the user calls for lights to be completely off. The result is that when wiring the common wire to an output of an additional channel on the DMX512-ANL, and simply programming the device to ramp voltage down on the first channel, and ramp up voltage up on the second channel, the lights will completely turn off. In simpler terms, output channel 1 will have no common output connection, but it will instead be connected to the common output of channel 2, where channel 2 will have no positive lead connected to its output.
Since the design of our system only required 4 channels of 0-10V dimming, we were able to make the project a success with only one DMX512-ANL. However, engineers bench tested this with a second unit entirely just for the “OFF” position controlling, and the testing remained successful.
