In Search of the Wireless Multimeter? It’s Finally Here

If you watched the two-season ABC show “American Inventor” or its more successful BBC counterpart “Dragon’s Den,” it was heartwarming to see men and women from all walks of life come forward and introduce ideas that came from tinkering, or long-nurtured pet projects, or moments of inspiration-- insanity, in some cases. Some were ready for prime time -- television and otherwise -- and others were half-baked, if not absurd or overthought.

We’ve all heard the perennial saying, “Necessity is the mother of invention.” Google is ever ready to validate this notion, serving up earnestly-documented instructions on how to build any number of tools and contraptions that someone decided we really needed or just thought it would be cool to actually make. Ma ny of these, for better or for worse, never make it past the hacker phase.

Take the notion of a wireless digital multimeter (DMM) for example. What a great idea, you exclaim. Imagine a handheld multimeter that could test and measure like a standard DMM but also send its readings to a remote PC for realtime monitoring, datalogging, plotting and analysis. Why haven’t they made one of these? So, you google the term “wireless multimeter” to see what’s out there.

The first page of results leads off with instructions on how to build a DMM with a wireless remote display using a $5 no-name multimeter, Nokia cell phone display, transmitter/receiver circuits, and a dose of schematics.

Another impressive project was a veritable hacker/maker’s dream: visualize an Arduino- and XBee-based wireless meter project that can actually stream data to a PC. (These hackers also mention an elusive, unrealized “multimeter glove” idea which I’ll deem as this category’s official hacking holy grail, surrounded by a shroud of solder smoke.) 

In all, the available kits and one-off projects represent some inspiringly creative “out-of-the-box” thinking and fodder for what are clearly very satisfying projects to undertake. Until the resulting meters are actually “battle tested” in the field however, the jury is out on whether the jury-rigs are robust enough for real-world testing and measuring applications, in terms of accuracy, reliability, safety, and durability.

Prospects for a wireless DMM were looking dim. Then, there appeared to be a glimmer of light at the end of the jury-rigged, search-results tunnel. This fall, a major DMM maker introduced a meter that has a detachable display for remote, wireless viewing of readings. What you could previously read only on the fixed display of a DMM, you could now take with you and read from a distance.

Overall, it’s a clever step in the right direction but its usefulness comes up short of our quest: true remote streaming of data back to a computer for display or datalogging.

With slumped shoulders, I clicked the “back” button and returned to Google, our virtual Sherpa. My skeptical eyes brightened with the discovery of another company’s recent wireless DMM introduction. What’s more, it was actually called a “Wireless Multimeter and Datalogger.” It turns out that Extech Instruments, a 38-year-old company located in Waltham, Massachusetts, on the fabled “America’s Technology Highway,” has recently rolled out a DMM that offers wireless data streaming back to a PC for datalogging and realtime monitoring.

The Extech EX540 is a new addition to Extech’s popular 500 series of eight industrial multimeters, considered the “toughbook” of multimeters. Extech’s proven, rugged, waterproof design can withstand a 6-foot drop, making it the ideal starting point for a go-anywhere DMM.

The innovative new meter offers wireless connectivity to your laptop or PC using a USB receiver dongle cable with a range comparable to Bluetooth (10m/33 ft). The EX540 transmits real-time data for trending and analysis (using the included software) on one of two available frequencies (433 and 914 MHz).

Built to industrial-duty specs, the EX540 is far from a wireless one-trick pony. This true RMS DMM can datalog up to ten thousand readings internally and also reads voltage, current, resistance, capacitance, frequency (with dual-range sensitivity for electrical and electronic work), duty cycle (dwell), continuity, diode testing (2.8V), and even temperature (using its Type K bead probe).

Accuracy is a tough-to-beat 0.06% and the meter is backed by a Category IV overvoltage safety rating, protecting users even on outdoor wiring. The easy-to-read, 5-digit triple display provides multiple simultaneous readings and also features a useful bargraph to simulate analog, “needle-swing” readings. The test instrument’s maker offers peace of mind with a three-year warranty and available NIST calibration certification.

The wait is officially over. The Google quest is finally complete. And it’s about time. For the invaluable versatility and added safety of remote monitoring and datalogging, the wireless datalogging multimeter has finally descended from the realm of smoky hackerspace dreams to reality.  Now, about that multimeter glove…

Abbreviated version featured on ECN magazine
Related product info on GlobalSpec