DCPower measuring multiple samples from multiple channels

[Basjong53]

Hello, I'm trying to measure multiple channels simultaneously on a PXIe 4141 source meter unit. A second SMU (PXI 4112) pushes a current sequence that I have to measure with the 4141.

I have the following code to do this:

This code works well for slower measurements, but not for faster measurements (e.g. sample rate >1000kHz). The timing is simply inconsistent, probably due to the limited software timing. I've used this strategy before using the Fetch Multiple.vi, which can measure multiple samples for each subVI call, but is limited to 1 channel. The Measure Multiple can measure multiple channels, but only 1 sample at a time. 

So is there any way to measure multiple samples (say 100ms of data) from multiple channels with this SMU? I need to work in the millisecond region.

[jacob_ng]

You definitely won't be able to sample near 1 kHz, as the 4141 simply isn't capable. The measurement aperture time (the amount of time spent resolving each measurement) is defined in the help docs ("Properties Supported by the PXIe-4140/4141") as being 0.01666666 seconds. As such, the fastest you can sample is around 60 Hz.

[santo_13]

Of course, you can measure at 1kHz but not the way you've implemented.

Notes,

• Do not use measure on-demand
• Reduce aperture time
• Change measure when property to - on-demand or trigger
• If configured for trigger, use the other sourcing SMU to send the Start Trigger to this SMU's measure
• Configure the measurement record size to the number of samples you want

Now, with the above-said notes, your current sourcing SMU will send a trigger when it starts sourcing, this 4141 SMU will react to this trigger signal and start measuring to meet the measurement record size at aperture time intervals.

[jacob_ng]

@santo_13 Thanks for pointing this out! Silly me thinking the default aperture time was the minimum.

I re-approached the issue with this new perspective and was able to get 0.1Ms/s readout on my 4142.

@Basjong53 I found this article very helpful for realizing santo_13's advice : How Can I Achieve Maximum Sample Rate With My NI SMU ? - National Instruments