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Electronic Theatre Controls Inc

Working with Fixtures that Share Multiple Parameters on One DMX Channel

There are some fixture manufacturers out there who combine parameters on a single DMX channel - usually a combination of intensity and strobe, but sometimes there are other functions.

Because Congo treats intensity as HTP information and other parameters as LTP operation, this combination of parameters can be difficult to control. The best situation is to use fixtures that provide a separate DMX address for each individual function, but we know that this is not always possible.

For devices that have these combined parameters, there is very little one can do to make this easier to control. Once suggestion would be to avoid using the level wheel with these devices as it is quite easy to overshoot "intensity" and end up with a strobe function running. Manual entry of intensity levels is much safer, and the +% and -% buttons can be used to step up and down in level relatively quickly. If the number of devices is relatively low, you could create a group per device where the intensity level recorded in the group matches the highest intensity output level of that DMX address and then use groups on masters to provide a more hands-on or fluid control of intensity for those devices (with the benefit of being able to use a master key as a channel selector as well.) Controlling the strobe half of the channel is best done with manual numerical entry or careful use of the level wheel.

If the device in question is an LED fixture, there is another solution available. In this case, since the intensity of the device is tied to the color mixing function, you can use Congo's "Fade with Intensity" setting in the template editor to create a second intensity controller for the device.

In the template editor:

  1. Set Red, Green and Blue (and any other colors of LED in that device like White or Amber) to use the Fade with Intensity setting (all the way to the right in the table - select the cell(s) and press MODIFY to add the check mark to these cells). This will allow the intensity of the channel to scale the output of the RGB+ parameters, effectively creating an intensity controller from outside of the LED device itself.
  2. Set the DMX address that has the device's native intensity and whatever other parameters have been included to an appropriate parameter name, like Strobe. Use this parameter to control only the non-intensity functions of that DMX address. Add ranges with text names to make controlling this parameter easier.
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