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A Review of the DMXCat by City Theatrical

One tool that has never found its way into my workbox is a DMX tester. Over the years I’ve tried a few in shops and at trade shows and never found one that quite fit into my workflow. In general, I’ve found that some of the popular models are either too fiddly to use, have poor visibility in low-light environments like a stage, and I even used one that required the user to memorize a series of colored lights and blinking patterns to figure out what was going on.

This seemed odd to me; after all, we live in an age where there’s an App For Everything. Why could our smartphones, tiny and capable computers most of us carry around on our person twenty-four hours a day, not be utilized as an interface for testing and controlling DMX devices? Today, we’re looking at the DMXCat device from City Theatrical, a widget that fills exactly this technological void I’ve been noticing.

The DMXCat is really two things, a physical DMX interface (dongle) for connecting to the DMX network to be communicated with, and the software that runs on your phone. The dongle is a small plastic box about the size of a pack of gum, with a single power button in the middle and a smaller button on the side for the integrated flashlight, and a female 5-pin DMX connector on a short cord. Charging the dongle is accomplished via a USB-A to Micro USB interface, a decision I particularly appreciated in this day of companies seemingly unable to resist putting proprietary connectors on their products. City Theatrical says that the charge on the DMXCat will last over twenty hours, though I did not use it continuously for long enough to test this. The dongle is very lightweight and compact, and completely unobtrusive on a belt or in a pocket.

The dongle connects to your phone via Bluetooth, and I had no trouble pairing the device with my phone. After paring, the application presents you with several functions, including DMX Controller, Fixture Controller, DMX Tester, RDM Controller, and a DIP switch calculator. (Note that I was testing the iPhone version of the software. The Android version will also present the user with a light meter and an RF spectrum analyzer, options which are unavailable on the iPhone.) The advantage of the wireless nature of this setup is readily apparent – not tethered to the physical DMX output, the technician is free to move about the stage, or plug in the device and not have to stand near the dimmers to see what’s happening with a light.

Firing up the DMX Controller section of the app, the user is presented with a view of the current DMX output of the dongle, which is visualized as a series of colored bars in rows, arranged in blocks of sixty-four. Tapping one of these blocks opens a more detailed view of the universe, showing precise numerical values for that block, and tapping again brings up a number pad for setting levels. This part of the app would be particularly useful for testing dimmers, or sending a precise value to a specific DMX channel or range of channels.

The next section of the application is the Fixture Controller. From here, the user is presented with a screen to find a personality for a variety of lighting fixtures, all of which are housed in an online database and regularly updated by City Theatrical. When the user selects a personality, it is downloaded onto the phone, and the user is then presented with virtual encoders to control the fixture. This download requires a data connection to work, but you can “Favorite” fixture personalities, which retains the personality file on your phone for use when you can’t access the network or the internet. I found using Fixture Controller very easy and intuitive, with the virtual encoders being easy to move both fast for quickly checking specific attributes, and slowly for more precise moves. Attributes that are meant to snap between discrete values (gobo channels, for instance) have convenient up / down arrows for switching between those values, a nice touch.

The DMX Tester provides four separate functions. DMX Analyzer shows technical information related to the DMX signal, including detailed signal timing information and received start codes. Transmit DMX allows the user to enter custom timings for these values, while a separate function displays all incoming DMX values. A Flicker-Finder function is also included which is intended to help diagnose and identify intermittent problems with the data network. Using the included 5-pin XLR turnaround, I connected the dongle to the output of my control console, and was able to monitor the output of the desk in realtime. Having various “levels” at which to view the DMX signal is intuitive and useful, from the “overall” view which shows an entire universe of channel levels with simple bars, to zooming all the way down to blocks of individual channels with their actual values displayed.

For the increasing number of fixtures that support RDM, the RDM Controller section of the application allows discovery, addressing, and reading of all the RMD data the fixture supports. Hooking up the DMXCat to another fixture I had in my house for testing, I was able to identify, set the address on, get full sensor readings, and perform all other RDM functions the light supported. While not intended for resetting addresses on multiple lights quickly, functionality like this can be a lifesaver for times when someone swaps a light and forgets to reset the address before sending the rig back into the air. While I only had one light in the chain, the unit will discover and generate a list of all connected RDM devices, and supports GET and SET for all PIDs (Parameter IDentifier), including custom user-defined ones. The RDM Controller also has a “DMX” button displayed next to all detected fixtures it finds. Clicking on this automatically downloads the correct fixture personality for the device and populates the start address for you, an intelligent feature that I greatly appreciated.

Overall, the DMXCat is one of the most intuitive and comprehensive DMX testers I’ve tried. Freeing the electronics from the yoke of simple low-resolution LCD displays makes an immense amount of sense, and the extras on the device – such as the DIP switch calculator within the app and the LED flashlight built into the dongle itself – show an understanding of what lighting technicians deal with every day in the field. Additionally, automatic downloads and address population of RDM-detected fixtures is a huge plus. The DMXCat dongle weighs a mere .3 lbs (.14 kg), and is 1.63” (41.4mm) wide by 3.75” (95.3mm) long, and .94”(23.9mm) high, and includes a belt clip with a safety attachment point, USB-A to Micro-USB charging cable, and a 5-pin XLR turnaround.

(This review was originally published in PLSN)

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