1. Cloud Connectivity Support

DMMs were traditionally hand-held devices which displayed electronic testing information only on the device screen. There was no way to easily share this information with other people or push information to the internet. State-of-the-art DMMs, like that shown in Figure 1, use a simple embedded app to connect to the Initial State IoT data streaming service, which can monitor and log data streams directly from the DMM instrument. Users can set measurement thresholds and receive email and text alerts when a threshold is reached directly from the dashboard.

Figure 1. Dashboard and Cloud data sharing make signal analysis portable from instruments to mobile devices

Initial State software-as-a-service platform integration gives the DMM remote monitoring capabilities, and also real-time interactive dashboards for data visualization, triggering and the ability to share data—all without the need for a PC or external software. The remote access feature allows users to monitor and analyze electronic data from the DMM remotely in any browser including on mobile devices anywhere in the world. This capability is available also for multi-channel DMMs, the so called “data loggers”, like the DAQ6510 which supports scan cards for multiple signals monitoring.

2. Test Automation Readiness

DMMs have traditionally used the Standard Commands for Programmable Instruments (SCPI) programming interface as uniform and consistent language for the control of test and measurement instruments. Previously, this was the only programming method available on a DMM. However, modern DMMs need programming flexibility to automate measurements to save time and mostly to meet demanding throughput requirements.

Figure 2. Functionalities and measurements setup should be accessible either from intuitive UIs and from API and functions to program

Modern DMMs often allow users to write their own code in languages such as Python to control the unit. In addition, DMMs may include factory installed applications which let users customize the user interface, change the display or how information is automated. Keithley High-end bench DMMs contain an embedded microprocessor and includes a Test Script Programming (TSP) scripting language which allow users to enter control commands and write test scripts that can be downloaded and stored inside the instrument itself.

Using an external PC software application, like Kickstart Instrument PC Control Software mean users with no programming skills can anyway configure basic test setups and collect data from multiple other instruments (including DMMs, power supplies, SMU instruments, dataloggers, sensitive units like electrometers and even several models of Tektronix oscilloscopes).

Users can control up to eight instruments at the same time and retrieve millions of readings from each instrument, leaving the setup running for days and days, which is for instance a typical need in reliability test for semiconductors components. The software contains plotting and comparison tools that help discover anomalies and trends.

Figure 3. Tektronix Keithley software suite control panel allowing full bench control and measurements reporting

Users can save test configurations and export data for additional analysis or to share test updates. The key thing with these evolved software suites is that they are regularly maintained and improved, and the licensing modeling allows the use of a floating license as well as annual license purchases as a more affordable alternative to a perpetual licensing purchase.

Figure 4. 99 points sweeping list uploaded on a specified power supply channel

A test automation software suite can also enable capabilities that the user interface of instruments would make it impossible to configure; a clear example is on the control of multichannel sourcing units like DC bench power supplies. A PC software would make the ability to control channels independently on multi-channel power supplies in both list sweep and bias modes simpler, otherwise extremely time consuming if done by pressing buttons on the instrument interface.

3. Suitable to new applications

When selecting the right DMM for you, resolution and accuracy are the main parameters to consider. Resolution is the level of detail that is measurable and displayed on the DMM, typically a number consisting of an integer and a half such as 3 ½ up to 7 ½ digits. The resolution of a DMM depends on the embedded ADC (analog-to-digital converter) used and on the maximum number of its counts during a full conversion. While DMMs with high resolution typically have high accuracy, these two specifications are not the same. Accuracy depends on digitizer accuracy, but also on noise level, stability of internal references and tolerance of all the electronic components used to design the DMM itself among other qualities. Some Keithley modern DMMs integrate a 1-MS/s 18-bit digitizer that provides an oscilloscope-like view of the signal being measured and allows users to capture fast transients, typically needed in the IoT space, combined with high accuracy and resolution.

Figure 5. Fast Digitizers on modern DMMs can help tracking rapid signal changes

A fast digitizer can capture the current power drain in all the states of an IoT product from the low power sleep mode to the full power transmit mode and load current burst. Capturing a profile of the load current allows the user to calculate an average drain current value, which is key to assess battery life based on the capacity of the battery powering the IoT device. There are emerging applications like End of Line testing for EV battery cells that demand specific levels of accuracy and measurement stability over time for voltage measurements like OCV (open circuit voltage) or current measurements like battery leakage current testing. Not all DMMs proposed by the test market can fit the job within requirements set by battery manufacturers and can actually cover voltage, current and resistance measurements with the required accuracy and multiple channel support.

Summary

Digital multimeter (DMM) test instruments have been used for decades to measure electrical values. DMMs have now moved into the digital age with features such as cloud streaming and interactive dashboards, touch screen interfaces, programmability, remote software control and fast digitizer features. Using older DMMs may hold back engineers from testing at the speeds and with the flexibility they need for today’s increasingly complicated devices. From connected homes and buildings to advanced automotive solutions and wireless communications, new DMMs can help drive digital product innovation. In production environments, modern DMMs are evolving to support test automation needs, speed up test configuration and grant the reliability and precision that manufacturing supply chain demands.