Feb 282014

newgraphicA theatre in the Pacific Northwest contacted us a few weeks ago.  Their space was set up with a pair of control systems running in parallel:  a DMX console and dimmers handle the theatrical lighting while a pair of wall-mounted 6-channel Lutron Graphic Eye 3500 architectural dimmers drive the house lights and some backstage fixtures.

Users on or near the stage can easily recall presets and adjust the lighting levels of the 12 connected circuits.


In the lighting booth, an ornery Windows XP platform runs Grafik Eye Liason software.  Liason provides a GUI for remotely recalling stored presets and adjusting individual dimmer levels.  This machine is in turn connected to a Lutron GRX-PRG interface, which talks with the wall controllers mounted near the stage.

The somewhat awkward end result is that the lighting designer has to use two separate systems to drive all the lights in the space. To this end, they asked:

“Would it be possible to remove the computer and drive the Lutron system directly from our lighting console?  Running both systems all the time is a drag.”

We’re pleased to report that the answer is an emphatic yes.

What We Did

Research revealed that the GPX-PRG receives RS-232 data from the XP machine, massages it a bit, then sends it to the Graphic Eye dimmers via a balanced RS-485 system. More germane to our situation, this RS-232 protocol is well documented.

DecaBox - Laser Etched

We proposed replacing the large, slow and inconvenient Windows XP computer with a DecaBox.  The new system would receive DMX, impersonate Liason and drive the GRX-PRG (and by extension, the downstream Graphic Eye boxes) as if the stock installation had never been touched.

The theatre approved our design, so we shipped up a DecaBox containing this custom firmware.

It took two or perhaps three minutes to connect the new hardware and set the start channel.  The custom firmware we provided worked instantly and flawlessly.  12 consecutive channels of DMX are monitored.  Any time one of them changes, the appropriate control string is sent to the -PRG interface.

Et voilà!  The lighting designer has complete and convenient control of every fixture in the space.

And in the client’s own words:

“We run a small community performing arts center in an old historic fire station and needed a way to have our DMX light board communicate commands with our RS-232 based house lighting.
The DecaBox was the solution we needed. We called, outlined the situation, ordered  and received the unit in a few days and had it up and running perfectly in no time. I was surprised at how a seemingly insurmountable problem was dealt with at such a reasonable cost with so little effort. Thanks so much for the quality product and service Engineering Solutions!”All the Best,~Matt @ The Firehouse Performing Arts Center

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