JEC

The Rack Mount Multi-Out DMX Engine

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Jan 082019
 

We were contacted by an integrator whose DMX fixture installation was large and complicated. They were using a Control4 system and chose our RS-232 DMX Engine as the master output controller in their system. However, in their case the standard practice of daisy-chaining large groups of fixtures* together was impossible, due to the required physical layout, access to connected conduit, etc.

During a telephone consultation, we discussed installing multiple DMX Engines throughout their venue. Because of the required layout, this would have been quite expensive. When we learned that their timeline was fairly relaxed, it made sense to commission a rack-mount system with 12 outputs, 12 isolated output drivers, and genuine Neutrik EtherCON jacks for easy termination of their installed wiring. Our friendly metal shop across town returned two pair of blue-anodized chassis sets a few weeks later:

Click to Enlarge
Click to Enlarge

The system follows the now-standard pinout for DMX over CAT5 cable. We use the DATA 1 pair (orange) with both brown conductors grounded:

CAT5 cables wired to the 568-B standard can carry DMX data

This rack-mount DMX Engine functions exactly the same as its smaller red brethren. The command set is identical; only the form factor and output count have changed. Need one? Let us know.

*This was the subject of a tech support call earlier in the week. When playing in the DMX world, there are two numbers to keep track of: channel count and fixture count.

Channel count is fairly obvious: a full universe of DMX contains 512 separate channels. This means that 512 single AC dimmers could drive 512 discretely connected incandescent light bulbs. When the author got started in technical theatre, the entire venue was controlled by large, dusty, hum-emitting 6 KW dimmers. About 30 worked properly. The command ‘set all to full time zero’ provoked a physical, visceral reaction from offstage left.

If using RGB LED fixtures, a universe can discretely control 512 / 3 = 170 fixtures without any overlap. Some modern moving lights à la rock concert gobble up 100+ channels each, which means only five can be individually driven on a single universe.

Recently, we completed a Christmas art installation where a single tree required nearly 23,000 channels of data running at 50 frames per second. We used e1.31 / sACN (DMX over ethernet, more or less) as the control backbone.

Fixture count is a different beast altogether. It relates to the total electrical load on the differential bus (D+ and D-, the DMX data signals). Each fixture connected in a daisy chain increases the load, and if it’s too high, signaling can turn erratic and be difficult to troubleshoot. Here’s a great article which dives deeper into the math. In any case, the ‘standard’ load for an RS-485 receiver (and by extension, a connected DMX device) is 1/32, which means that 32 devices can be safely daisy-chained together and driven successfully by a single master controller. If fixture load isn’t explicitly called out in a device’s datasheet or instruction manual, assume 1/32 load.

For slightly more money, some manufacturers (including us, as has been required by clients from time to time) design DMX input stages with 1/256 load receivers, which allows up to 256 devices in a single daisy chain without introducing signal issues.

Bottom line: make sure both your channel count and fixture count are within acceptable ranges. If fixture count is too high, consider using what’s called an optosplitter, which receives a signal and then regenerates it multiple times across multiple outputs. Or call us and we can help with something custom.

A Handful of Weekend Wonders

 Case Study, DMX  Comments Off on A Handful of Weekend Wonders
May 242018
 

In addition to the standard products listed in our web store, we do quite a bit of custom / one-off work.  Here’s a collection of recent quick-turn projects we’ve recently shipped.  All images here can be enlarged with a click.

The DMX Triggered DMX Selector Switch

A theatre up north had several lighting control sources (a large lighting console, several wall panels, etc) plus safety rules which require certain channels be kept at a specific intensities 24/7.  Based on their sketch and pseudocode, we designed a five input DMX router.

For any input, setting a specific channel to a specific value lets that DMX source take control, and its full universe of data is passed to the ‘DMX Out’ jack.  In addition to switching between the five inputs, the system forces the safety channels to their proper values and sends the final signal downstream.

If you think about it, in this situation, a standard DMX merger running either ‘highest takes precedence’ or ‘most recent takes precedence’ wouldn’t work properly.  The system contains a USB interface for painless field firmware updates if they’re required.  Each DMX input is optically and galvanically isolated from its neighbor, which should keep lightning propagation to a minimum.

Side note #1: Our stock DMX receive circuitry has been installed in thousands of locations worldwide.  And in over a decade, we’ve never, ever received a report of it being damaged in any way.

A Countdown Timer / High Power UV Trigger System



Though not one of our usual DMX / MIDI / serial projects, we’d worked with staff at this childrens’ museum several times in the past.  It’s rewarding to deliver something which didn’t exist, anywhere in the world, until we made it so.

In a dark corner of the museum’s ‘color and light’ lab, an entire wall was painted with photoluminescent paint.  When excited by a xenon strobe light, flashlight or blacklight, the paint activates and glows green for several seconds, slowly fading away as the energy dissipates.

The designers envisioned a ‘photo booth’ where patrons could press a trigger button and then pose against the wall.  The paint is then activated by the light source, leaving a glowing silhouette.

We sourced a pair of 10W UV lights (395 nm and super intense, causing mild eyeball sunburns after twenty seconds of near-field exposure) and a 4″ illuminated pushbutton.

I felt that standard 7-segment displays looked mechanical and dated, but a quick search online returned a slightly stylized 7 segment font – ‘Modern Mini’ in bold italic.  The ~5 degree slant looked fun, and I liked how the segments jauntily meshed together.

 

It took a few steps in the CAD program, but the digits were converted to vector data.  On the shop’s laser cutter, we created a 7-segment display measuring 300 x 200 mm.   The display was loaded with LEDs whose brightness and color can be arbitrary controlled, segment by segment.   The finished assembly is a sandwich of several acrylic layers, using black, clear and white stock.  The segments are inlaid in the black layer, then covered with a clear protective layer.  The layers allow the light for each segment to be channeled, diffused and displayed in a pleasing way.

Also, the giant pushbutton contains a white LED which can be set to any intensity.

Our custom circuit board include a small display for changing and storing settings (UV / flash exposure time, countdown time and ‘timeout’ time).  It was somewhat overbuilt, supporting 4 contact closure inputs, 4 buffered logic level outputs, a pair of high power output stages and 4 SSR (solid state relay) outputs, in addition to connections for the countdown display and a smattering of indicator lights.

During normal operation, the display reads ‘5’ in green, and the pushbutton pulses slowly, à la sleeping iMac, drawing attention to itself in a tasteful way.  When the button is pressed, the white LED turns off and the countdown begins.  At time zero, the UV sources pulse for their specified time, the display switches to blue and begins begins counting down from the ‘lockout’ value, giving patrons a chance to enjoy their artwork as the phosphorescence slowly fades away.

Once the lockout time has passed, the pushbutton resumes its quiet pulsing, the display switches back to green and waits patiently for input.

Side note #2: The blue / green color scheme was chosen in a nod to the industrial designers at Disney. Green means go, blue means wait.  Red signifies danger and problems, so don’t bother the public unnecessarily.

 

 

 Posted by at 4:53 pm

The Ethernet DMX Engine

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Feb 262018
 

It’s finally (almost) here.  We’re planning a release date in early Q2 2018.  The Ethernet DMX Engine will feature a nearly identical command set as our current RS-232 version.

As we make final decisions regarding the panel layout and connections, we’d love your feedback.  Please take a few seconds and visit this very short survey:

Features – The Ethernet DMX Engine

 Posted by at 7:33 pm

DMX Multi-Zone Universe – A White Paper

 Case Study, DMX, RS232  Comments Off on DMX Multi-Zone Universe – A White Paper
Mar 092017
 



Mike Slattery, CTO over at TEKVOX in Dallas, wrote a short white paper about how our DMX Engine can easily control fixtures in multiple physical zones, and shows how the Engine’s ‘mask’ command makes it simple to adjust the look in each zone without affecting surrounding areas.

He writes from a Crestron background, but the principles apply to every major control platform.

Take a look! DMX Multi-Zone Universe [PDF]

 

 

 

 Posted by at 5:47 pm

DMX Control of a Daktronics Venus 7000 Video Controller

 Case Study, DMX, RS232  Comments Off on DMX Control of a Daktronics Venus 7000 Video Controller
Feb 142017
 

Canucks Arena & Video Ribbon. Photo from GLOBETREKIMAGES / 604 NOW FLICKR POOL

This was a fun one.  Turns out, the Daktronics Venus 7000 video controller can be trained to play content based on incoming RS-232 messages.  And, the trusty DecaBox can receive DMX and output all manner of RS-232 content.  When the dust settled, we ended up shipping a somewhat-modified version of our DMX to ASCII firmware.

Here’s the story, straight from the customer:

Recently, I was given this task of creating a lighting board to Daktronics Venus7000 lighting trigger and started out by looking at my relevant device ‘gozintas and gozoutas’ (ins and outs). 

I do not dabble too much in lighting control technology although I knew we are using a Grand MA on PC. I do provide in-house second tier support on our Daktronics LED systems and servers so I also knew that I needed to create some simple ASCII data strings on an RS-232 serial port. 

After asking the Google, I was able to find some articles about converting DMX to serial. This is the link that came up: http://response-box.com/gear/decabox-protocol-bridge-overview/ and this Decabox looked like the exact piece of ‘glue’ needed to convert lighting transitions to a Daktronics triggers. 

I took a bit of a chance and purchased the Decabox, (John Chapman at Engineering Solutions Inc. was also very helpful in that he returned my call and assisted me in determining a data scheme). I went back a to Daktronics Engineering and they were good with John’s proposed data string.  

Shortly after submitting my order, I received the Decabox which John had  pre-programmed and we were ready to test. We were very quickly able to see the appropriate serial data in our Dak server room and soon after got Dak to remotely configure the serial listen port. 

Success! 

This has solved an ongoing issue with playback synchronization of Daktronics content playback, and our house lighting.  We now have consistent and repeatable triggers during our game start opening sequences, whereas before we relied on an intercom countdown to mouse click (which was not very tight!). 

I would not only recommend this device, but also have kudos for John Chapman’s support and timely follow ups to our questions. 

GS | Broadcast Technician
Canucks Sports & Entertainment | February 2017

Need something similar? Contact us and let’s get started.

 

 Posted by at 11:07 pm