Last night I played with the pro version of the BenchVue multimeter application, without first reading any of the documentation, 'cause that's what most engineers do, right?
Turns out the interface is intuitive enough and peppered with enough pop up help bubbles that I was able to do some useful work right off the bat.
As mentioned in my blog post about my plan for evaluating BenchVue, I hooked up a 4 m string of WS2811 based RGB LEDs to a PIC microcontroller platform that is programmed to output various changing light patterns.
I connected a Keysight 34461A multimeter to measure end of string voltage. End of string voltage is of interest because there are 240 LEDs in the string and the amount of current drawn by the string varies significantly with the number of LEDS illuminated.
A common problem with long LED strings running at maximum brightness (especially with white light), is a noticeable dimming of the LEDs toward the end of the string due to voltage drop along the length of the string.
My interest was to see if I could use the pro version of the BenchVue multimeter app to quickly set up a data log of end of string voltage as I sent various illumination patterns to the string.
With only a few mouse clicks I was able to set the meter function, NPLC (number of power line crossings), and duration of the data log. A single click started a real time strip chart log on the screen.
I will provide more detail on the importance of selecting an appropriate NPLC setting in a subsequent blog. Suffice to say here that if you get it wrong the data gathered in the log can end up being useless.
I learned two important things from about two hours of playing with BenchVue last night. First, the basic features on the multmeter app are super easy to use and quite intuitive (to me). Second, data logging can reveal unexpected circuit behaviors. The end of string voltage pattern produced by one of the illumination patterns I tested was not what I expected. The beauty of the BenchVue data logging feature is that I was able to quickly and intuitively manipulate the multimeter and logging functions, which left the majority of my attention available to concentrate on investigating circuit behavior. That is the way tool operation should be experienced. Operation should be essentially transparent and automatic, allowing the tool user to concentrate on gaining insight into a problem.
I'll upload details about the test configuration I used and the unexpected end of string voltage pattern when I 'm back at my test bench.
Mark A
