National Instruments has released VirtualBench, an all-in-one instrument that integrates a mixed-signal oscilloscope, function generator, digital multimeter, programmable DC power supply and digital I/O. We got a sneak preview at the device and a chance to test NI's claims that it provides the most common functionality affordably and opens up new possibilities for how engineers use benchtop instruments.
As engineers are used to working in a very mobile and agile way, the idea of replacing physical instrumentation with a virtual set up will appeal to many. Therefore, I was keen to test out some of the claims myself - in particular the claims that it provides the most common functionality affordably and can also open up possibilities for how engineers use benchtop instruments.
The VirtualBench comprises an all-in-one instrument that integrates a mixed-signal oscilloscope, function generator, digital multimeter, programmable DC power supply and digital I/O. However, it has an interesting twist – users will be able to interact with the VirtualBench through software applications on PCs or iPads.
When the next-generation iPad launches later this year, it could be a very ubiquitous workhorse for electronics research and production test benches and, particularly, for the mobile trouble-shooter. The compact 10 by 8in (250 x 200mm) footprint combines six conventional test bench instruments reducing the space typically required to accommodate them. There is, apparently, also an all-important cost saving to be had.
After connection to a mains supply and hook-up of the USB cable to a laptop, the NI Virtual Bench springs quickly into action. On pressing the power button, the unit uploads its operating software on to the laptop with no prior preparation and, after agreeing to the licence, the operating screen is instantly displayed.
The location of the instruments on the screen mirrors their location on the front of the NI Virtual Bench. The oscilloscope trace dominates the screen and can be made to fill it at the touch of a button.
The interaction with the display uses the usual laptop or mouse controls – click cursor on buttons to activate items; click and drag sliders to increase/decrease amplitudes, frequencies, etc.; scroll to increase/decrease values; up/down arrow keys to increase/decrease specific digits; highlight and overwrite numerical values.
The oscilloscope and function generator were tested together by linking a coax cable between fgen output BNC and CH2 input. CH1 input was connected to the integral 1kHz test signal. The function generator was switched on and adjusted to an arbitrary magnitude and offset value.
The oscilloscope is quickly kicked into life by selecting the ‘auto’ option for set-up (rather than ‘default’). It sets the amplitude and time axis at reasonable values for the signal being observed and sets triggering on automatic at middle amplitude. Thereafter it is easy to adjust for your specific needs.
A long expanded thumbnail of the trace appears at the top of the screen, central on the trigger point, with the main screen portion highlighted. The main screen portion is approximately a 13:1 zoom-in on the expanded trace. A second analogue channel can be added and a third ‘math’ channel set-up (A+B, A-B or A*B) or digital channels added (any or all of the 32 channels from the logic analyser, the 8 channels from the I/O plus clocks and function generator triggers). Two cursors can be added and moved as desired.
Cursors can be for time; track or voltage. The time cursor can be further set for channels 1, 2 or ‘math’; logic analyser (four, 8-bit words); clocks 1 & 2; digital I/O 8-bit word; and ‘misc’. There is a ‘measurement’ window displayed from the icon.
The interface contains a host of digital data on frequency, period, pulse widths, duty cycles, rise and fall times, voltage amplitudes, pk-pk, mean, rms and much more besides. There is so much information, the window has to be scrolled to reveal all of it. This window can be moved around the screen to allow other relevant information to be seen simultaneously.
The little camera icon takes a snapshot of the screen as a .png file, which is time-stamped. There is, however, no feature to allow you to add text to define what was being tested at the time, so you had better have some notes to allow you to make sense of the .png files at a later date. The data on the ‘measurement’ window is not captured during a .png snap. There is, handily, an adjacent icon which triggers a snapshot Excel .csv file, capturing some 600 lines of data at a 4microsec sample rate with equal capture before and after the trigger point.
The power supplies and digital multimeter were checked relative to each other. The multimeter indicated the power supply set values to be within 3mV, while the power supplies are adjustable and had been set at nominal +5V and +/-20Vdc. It should be noted that the +/-20V supplies are ‘floating’ compared with instrument earth, but can of course be connected to earth.
The logic analyser comes with push on connectors suitable for connecting to test pins on PCBs – 32 signals plus two clocks can be monitored. Add the I/O signals and three from the function generator for a total of 45 digital signals to be displayed on the ‘scope. A pattern from the same 45 signals can be used as the trigger, making this a powerful tool for signal analysis.
Beyond this, the NI VirtualBench can be interfaced with and automated by LabVIEW.
NI says that the VirtualBench app for iPad will be available in the App Store later this summer.
John Hamilton MIET is a chartered engineer with more than 40 years experience and currently runs his own consultancy, Kappa Konsultants Ltd
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