In the days of analog control it was easy to figure out if a control cable was good or bad. A simple continuity checker was all you needed to know whether or not it would pass signal. In the days of digital control it’s not that simple.
If you were to peek inside of a DMX cable you would find at least two conductors (sometimes four) separated by insulation. That description also fits a capacitor, and a cable can indeed behave as one. For an analog signal it’s not a problem because to DC (which is close to what an analog control signal looks like) a capacitor is an open circuit. Therefore, it doesn’t adversely affect the signal. But for a high frequency digital signal, the capacitance of the cable can cause signal degradation and lead to control errors. And to insure that a control cable is low capacitance and that the solder joints are good, it takes a high frequency tester and not a simple continuity checker.
That’s where the Swisson XMT-120 DMX Measurement Tool comes in handy. But it’s not just a cable tester, it’s a multipurpose, handheld, battery-operated tool that can help you install, troubleshoot, and maintain DMX512 networks. It’s very intuitive and easy to use, and it has some unique features.
Physical
The unit fits nicely in your hand and has a solid feel. It’s about 4-3/4 inches long, 2-3/4 inches wide and 1-3/4 inches deep, and it weighs less than a pound with the battery in it. It’s constructed with powder-coated cast and extruded aluminum and it has a membrane switch front panel and a nicely sized backlit LCD display. The display light can be turned on and off to save battery time when it’s not needed. On the bottom there is one 5-pin male and one 5-pin female XLR panel-mount connector for the input and output and small low-voltage power input connector for auxiliary power. On top there is a battery compartment that takes a 9-volt battery.
Modes
When you first turn it on, it quickly displays the model number and a customizable name before it goes into the default mode (Receive DMX mode). There are six modes, including Receive DMX, Send DMX, Cable Tester, Sequence, Fixtures, and Options.
In Receive DMX mode the XMT-120 can be plugged into a DMX network or device to receive data and it will display data in percentages, decimal values or hexadecimal values. It can display one channel of data at a time with sequential access to each channel, a table of 50 channels of data, or a graph display showing all 512 channels at once. In the graphic display the individual levels are extremely small.
In Send DMX mode it outputs up to 512 channels of DMX but you have to change the levels one channel at a time, stepping through each channel with the navigation buttons. Once you land on a channel you can take the dimmer level to 0, half or full with the touch of a single button. Alternatively you can increment or decrement the DMX value with the “+” and “–” buttons.
Cable Test mode is interesting because it has a graphical display showing the five pins plus the shell forboth the input and output connectors. A line moves in sequence from the bottom pin to the top pin, and if there is a signal connection between the corresponding input and output pins, the line connects the two. It’s simple and effective.
In Sequence mode you can record up to 32 scenes of up to 100 steps each and play them back with variable sequencing speed and crossfade times. The scenes can be recorded in Send or Receive mode, so you can create your own scenes with the XMT-120 or you can capture them from another console.
The Patch Fixture mode allows you to assign a starting DMX address to up to 32 automated lights, name them, and assign names to each of the control parameters. This feature may not allow you to program and run a show, but it certainly could aid in the task of setting up, testing, and troubleshooting fixtures.
The Options mode has several interesting options. The first gives you the ability to name the XMT-120 unit, so you could enter your name or your company’s name, and when the unit is first turned on it will come up in the display. There is an option to store the current settings as the defaults and another to display the minimum and maximum values seen by a particular channel. I’m still trying to figure out the intent here, but I suppose it would be useful to check values of a channel that is not currently displayed. The other option in this menu needs no explanation. It’s an option to display the binary equivalent of any given channel. For example, if you select channel 13, it will display 00001101. I sure wish I had this the last time I had to set the DMX addresses in a rig full of Intellabeams or Dataflash.
Surprises
The unit comes with carrying pouch that has a belt clip on the back. It also has two adapters on either side of the pouch that somewhat resemble bullets in an ammunition belt. I had forgotten about them when I was trying out the cable test function. I only had a three-pin DMX cable and since the device only has five-pin connectors, I thought I was out of luck — until, that is, I remembered the three-to-five-pin adapters that come with it.
The XMT-120 is one of the handiest tools a lighting professional can have, whether you are an electrician, technician, programmer or stagehand. If you work around lighting systems, you can use it. It can get you out of a bind when you’re installing, testing, programming, or maintaining lighting systems. It’s rugged and compact and it has lots of useful features.
Swisson XMT-120 measurement tool
What it is: Multi-purpose DMX networking tool
Who it’s for: electricians, technicians, programmers, stagehands and anyone else who works around DMX systems
Pros: small, lightweight, versatile, and easy to use
Cons: graphic display is hard to read
Retail price: $356
