A multimeter for an electronics engineer is as essential as a stethoscope is for a physician. It is an extremely useful, indispensable diagnostic tool for electronics design professionals, students and hobbyists—but is there anything more to it? This article provides some insights into the latest trends in multimeters
A multimeter is a very handy electronics measuring tool that helps in determining several electrical properties. Today, multimeters are available with advanced measuring capabilities for measuring capacitance in farads (F), inductance in henries (H), conductance in siemens (S), frequency in hertz (Hz), percentage duty cycle and also decibels (dB). With an appropriate test probe, such as a thermocouple, the temperature can also be determined in degree centigrade (°C) or Fahrenheit (°F).
The simplest electrical measurement testing tool, multimeter, has been evolving as a high-end electrical and electronics testing equipment to serve complex testing needs. Moreover, the latest multimeters incorporate a higher level of integration, connectivity and advanced features.
The multimeters are either handheld or bench-top type. Handheld multimeters are primarily used for insulation and other measurements in field. Bench-top multimeters are used for higher-accuracy applications in research laboratories and electronics design houses.
The benefits of digital multimeters (DMMs) based on the increasingly popular modular platform, especially PCI eXtensions for instrumentation (PXI), are also discussed in this article.
Engineers and technicians often come across situations where they have to take readings from an operating machine, or from points high above the ground, or measure multiple points at the same time. Improving safety and productivity at work are very important. It appears that multimeters are evolving to meet these demands from the users.
Wireless technology is used to solve these issues, without compromising the safety of the user. It allows to link distantly located multiple modules to a PC, tablet or smartphone. This allows remote logging of measurements in real time, and subsequently makes analysis and troubleshooting easier.
There are also Bluetooth-enabled multimeters available in the market. Wireless adaptors allowing log data from multiple DMMs in your computer/smartphone are also available now. Addition of these features provides an edge to the new multimeters over the traditional multimeters.
Multimeter with a remote display is another interesting product developed in this category. It allows detachment of the display from the body of the instrument and take readings from a remote location.
Having highly scalable dense software architecture is very crucial for all the instruments. Hence in-line processing technology, such as field-programmable gate arrays (FPGAs) and real-time processors, are being adopted for multimeters. With the help of such technology, users can write an FPGA program to reconfigure the input/output (I/O) behaviour in order to define and design a particular multimeter as per requirement. Therefore, unlike the traditional multimeters, users can have a software-defined instrument rather than a vendor-defined one. The development time of a test system has been a great challenge and should be reduced considerably.
With regard to the wireless technology in the multimeter space, there are a growing number of software and mobile applications—some developed by vendors and the others by independent developers—to help analyse process and simplify user interface. It is important that the software controlling these instruments is highly integrated and efficient.
Nowadays, people expect more measurement capabilities than the traditional voltage, current and resistance measurements that were typically performed by a multimeter. Research is ongoing for including more measurement capabilities, quick and better integration and development of the intuitive abilities of the application. This R&D is focussing on the inclusion of additional measurements by integrating DMM with other sensors, measuring devices and switches.
Currently, more devices such as voltage and current amplifiers, source measure units (SMUs) and digitisers or oscilloscopes are combined with the typical DMM functionality.
The integration of several instruments into a single module helps in developing ‘managed test systems’ that allow users to combine traditional multimeter functions with other elements/functions such as system monitoring, diagnostics, data logging, configuration and calibration.
Now it is no longer a stand-alone DMM, instead it has additional capabilities of attached elements that are combined in a single instrument. Such DMMs allow the users to take readings from multiple points and make more enhanced digital measurements in order to characterise their systems much more accurately, thus increasing customer efficiency.
So what we can expect in the DMM space is the ability to create, design and develop very high-end specification instruments.
The need for such integrated products depends on the application field, the variety of the user’s job roles and their affordability. Now there is a provision for the users to buy a base instrument with limited and affordable set of functionality and upgrade the features in the future.
In brief, the attempt in R&D is to focus not just on a single multimeter but also on driving customer efficiency by enhancing multimeters’ capabilities for a variety of measurements.
Modular platforms combine dynamic and static instruments
Integrating multimeters with other instruments is difficult and extremely challenging, especially in the case of traditional box instrument, as they do not share a common platform.
If each instrument has its own power supply, timing, triggering and synchronisation signals, the only way they can be combined is through external cables as there is no integrated software that can bring them together. This is the reason we need a common, shared modular platform. Modular instruments provide a flexible, organised, software-defined solution for complex integrations.
The latest modular multimeter platforms, such as USB, PCI and PXI, allow the users to make various types of measurements by investing in one particular instrument. But this is possible only if all the combined instruments share a single platform.
In addition to making static DMM-type measurements, the engineers can also make dynamic measurements such as rise time, fall time, FFT and other frequency domain by using such platforms. Since DMM measurements are slower, combining them with faster measurements is always a challenge. But having modularity and a combination of different instruments into one instrument, we can combine the static and dynamic measurements together in a single platform.
Using certain technology, such as test script processor (TSP), of one particular brand can enhance system control. This technology provides ‘smart’ instruments the capability of performing distributed processing and control at the instrument level versus a central PC.
Improving user’s experience
From my discussions with multimeter vendors, I noticed that most of the vendors are trying to improve user experience rather than improving the specifications of the instrument. The idea behind this is to show how easily a user can use the instrument and how easily it can be integrated with the system. The manufacturers are trying to add more value in terms of the invincibility of that product.
Better-quality displays are very important aspect of improving graphic user interface (GUI). Full-colour, wider graphical displays can be found in some recent multimeters. There are products using organic light-emitting diode (OLED) displays with bright and easier screens for the users to see. But there is still a long way to go for improving customer experience.
Some of the latest models have several built-in features such as backlighting, charts, histograms, trends and statistics.
Another new feature is the ability to see ‘live’ measurements simultaneously from multiple modules on a single screen. For example, newer models often include the capability of simultaneously displaying two readings (for example, monitoring voltage and temperature at the same time), measurement trending or even histograms. This makes the GUI more intuitive.
Simplifying user interface is also a priority for developers, so that the tool can be easily handled both by experienced professionals and inexperienced users. As a part of this trend, we find that many multinational brands have been providing multimeters with a selection of local Indian languages such as Hindi, Tamil and Bengali. This is a rather interesting development for a basic product such as a multimeter, where a user is expected to simply read the values. This, I think, would greatly aid in improving user experience.
We also find instruments with increased safety, protection level and ruggedness. A safety aspect is seen in recent models, where you have non-contact voltage detection and measurement. This allows the user to know the presence of live wires in the working area even before the tool comes in contact with it. Robustness is important, particularly for handheld multimeters, because such devices are used by people on the move.
What does demand show?
True RMS multimeters are being widely adopted because nowadays people are more aware of the precise measurement requirements. Distributors say they have been observing, over the years, a growing demand for branded multimeters in the market. Users, generally, trust branded multimeters when it comes to the quality, reliability and customer services for the product.
Moreover, several branded multimeter models are now available at a low cost, and hence their demand has increased amongst hobbyists and DIY enthusiasts too. Reducing the voltage range, disabling current meter or reducing the form factor to create pocket-sized instruments are amongst the factors contributing to this reduction in price.
The author is a dancer, karaoke aficionado, and a technical correspondent at EFY. Find her on Twitter @AnuBomb.