How do I read data from a DMM or DC Power Supply at a specified rate?

[Anil Kandangath]

I have a PXI system with 4071 DMMs and 4110 DC Power Supplies. I want to be able to measure the power consumption of my DUT as it performs various operations. This is what my process flow looks like:

1. Configure DMM and Power Supply 

2. Wait for DUT to go into a certain mode

3. Start  Acquiring data from DMM and PS.

4. Wait for DUT to get out of this mode

5. Stop Acquiring data from DMM and PS.

Since the duration of step #4 is uncertain, I cannot tell the units to collect a predetermined number of samples and give it back to me. Instead I have to take readings as long as it's required. 

I'm attaching screenshots of my setup and read process. The reading is done inside a timed loop which is running at 1kHz.

The problem is that using niDMM Read Multi-Point or niDCPower Measure Multiple takes 5-9ms before I get a reading, so I'm not really getting 1ms resolution in my data. I'm sure there are other folks who have had the need to read data from these devices with better time-resolution, so if anyone can point me in the correct direction, it would be great. I'm pretty sure I'm not doing the correct thing here.

[Anna_K.]

Hello Anil,

I would like to see if I can help you out, let me get some advice from our RT programming team and get back to you with some tips.

Regards,

Anna K.

[Dennis_Knutson]

What is really confusing to me is why you are even using the multi-point function when you set the sample count to 1. If you want multiple points, request multiple samples and let the DMM acquire them at a rate you specify. If you want a single sample, use the normal Read. You also need to pay attention to how fast the DMM can acquire. If you want the fastest sample rates, you might be a lot better off with a DAQ board.