Peter, Jon and I are building a Programmable Electronic Load. In this series, I'm using test automation to characterise the device. I'm now including an oscilloscope to add up to 4 additional measurements to the test recordings.
The process tests the load for a range of voltages and currents, and measures some points of interest. The results are logged to a spreadsheet. |
In the previous post, I documented the core test cycle.
It puts the instrument through a wide set of operation points, ramping both input voltage and loaded current from very low to the highest ranges, in any combination within the operational field.
I used the on-board ADCs to collect data from the instrument. This was enriched by info provided by the power supply.
But there are more points of interest. Various points in the control circuit are very interesting as data points.
They help to fully understand how the instrument behaves in practice. But they aren't connected to an ADC.
To measure them, an additional instrument is needed.
I don't have DMMs that are LabVIEW enabled (if you prefer me to do the measurements with a SCPI enabled DMM, send one. Address available on request 
).
The best option I have is a Rigol DS1054Z oscilloscope. It offers four extra voltage probes (channel 1 - 4) with reasonable precision.
Good enough to get a view on the instrument's internals.
This blog shows how I included the oscilloscope in the already existing test setup, as an optional instrument.
Optional
I don't want to use the scope each time I want to measure the efficiency of a device. The base setup should be easy to set up.
That's why the process can run with or without the scope included. A switch on the start page determines if the flow looks for the scope and takes measurements with it.
In the block diagram, you'll see that any process that uses the scope is in conditional blocks:
The results of the scope measurements are logged into a spreadsheet, next to the other measurements in the flow.
If the scope is not active, these columns exist in the file but are empty. I could alter the flow to not have these columns but didn't.
That's it. A little blog post that shows that you can make LabVIEW test setups flexible.
A quick setup if you are looking for a few datapoints.
More elaborate when you want to record additional points of interest.
| Related Blog |
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| Programmable Electronic Load - LabVIEW Test Automation: Characterise the Instrument |
