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Advances in test instruments' user interface (Part 2)

Posted: 30 Jun 2014     Print Version  Bookmark and Share

Keywords:Keithley  touchscreens  GUI  source measure unit  SMU 

Read Part 1 of this series here.

Keithley's approach to usability involves minimising the number of front panel buttons and knobs while transferring many functional controls to the reconfigurable capacitive touchscreen display. The design team placed high emphasis on the level of information provided through the touchscreen, including allowing the user to confirm easily how the instrument is configured. The user can tell at a glance the instruments measurement range, the source value, and the pre-set current limit.

The touchscreens buttons work in conjunction with the physical buttons and the quick- navigation control knob to help users navigate instrument operation with confidence. The push buttons provide quick access to menus, quick configurations and function selection, triggering, and the context-sensitive on-screen help. The control knob allows operating the on-screen controls mechanically without the need to touch the display for situations in which screen contact is impractical. The knob also allows selecting menus, tabbing through editable fields, and increasing or decreasing values.

The Model 2450s five-inch touchscreen has three display regions. The on-screen buttons indicate the configuration settings, including the measurement range and set values. When the instrument is in Auto-Ranging mode, the display will also indicate the range on which the instrument is operating.

Flat menu structures
Many test vendors continue to design instruments with multi-level menu structures, which can be confusing to navigate. Instruments that use soft-key architectures sometimes force users to go as much as six layers deep to reach the desired selection. Keithleys touchscreen GUI eliminates this confusion with a flat menu architecture that ensures any configurable parameter is just two on-screen touches or pushbutton presses away.

As shown previously, the Model 2450s main menu screen makes instrument navigation an intuitive experience by representing many functions and parameters graphically.

For example, to create a simple current vs. voltage (I-V) sweep on the Model 2450, the user simply presses the front-panel MENU button, then selects Sweep from the Source column.

The touchscreens swipe capability simplifies revealing detailed measurement information quickly without the need to navigate a confusing menu structure.

It takes only two steps to reach the screen for creating a sweep, with no need to go back and forth between multiple displays and menu levels.

Productivity improvements
To verify the productivity of this new approach to instrument configuration, we comparedthe Model 2450s usability with that of another source measure unit (SMU) instrument that uses a soft-key architecture. We created four common user scenarios to assess how many steps were required to set up each SMU from the front panel. All tests were performed starting from the instruments power-up default setting.


1. Digital Voltmeter Operation
 • Set up the instrument to behave just like an autoranging digital voltmeter.
2. Ohmmeter Operation
 • Set up the instrument to behave just like an autoranging digital ohmmeter to make a 4-wire resistance measurement.
3. Source V, Measure I. Then Source I, Measure V
 • Set up the instrument to source 10V, set the current limit to 200mA, and then measure the current.
 • Set up the instrument to source 10mA, set the voltage limit to 20V, and then measure the voltage.
4. I-V Sweep
 • Create a linear sweep from 10V to +10V with a step size of 100mV and an I-Limit (compliance) value of 100mA. Set a source delay time of 500ms.

The results of the four tests are outlined in the following table.

Table: Results of four user scenarios.

Configuring measurements using Keithleys touchscreen SMU takes substantially fewer steps than the competitive SMU that uses a soft-key approach for typical use cases, making it possible to achieve significant productivity gains quickly.

Bench instruments that employ a software-definable touchscreen system will improve productivity, allow a faster time to measurements, and offer a lower cost of test than traditional hard-key and soft-key front panel interfaces. By using a touchscreen approach and maintaining consistency in the location and functions of pushbuttons and touch buttons, users will be able to move quickly from one instrument type to another with minimal training. Even those who use the instrument infrequently can get back up to speed quickly simply by using the instrument.

With more information about the instrument setup and measurement condition literally at users fingertips, new interactive instrument will enable scientists and engineers to learn faster, work smarter, invent easier.

About the author
Jonathan Tucker is a Senior Marketing and Product Manager for Keithley Instruments, which is part of the Tektronix test and measurement portfolio. He joined Keithley in 1987. During his tenure, he has served in a variety of positions, including manufacturing test engineer, applications engineer, applications manager, product manager, and business development manager. He holds a BSEE from Cleveland State University (Cleveland, Ohio) and an MBA from Kent State University (Kent, Ohio). He was a 2007 recipient of the Nano Science and Technology Institutes (NSTI) Fellow Award for outstanding contributions towards the advancement of the Nanotechnology, Microtechnology, and Biotechnology community. Jonathan is a Senior Member of IEEE and was recently the IEEE Nanotechnology Council Standards Committee Chairman. His technical interests include nanotechnology, amateur radio, software defined radio technology, and JAVA/HTML web programming.

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