PC multimeter

[giorgos]

Today as i was searching into agilent site , this item attracted my attention http://cp.literature.agilent.com/litweb/pdf/5990-9035EN.pdf
This category is completely strange for me. My main conclusion is that the exclusive destination of theese meters , is laboratory use. My questions are many. Accuracy of these meters is depending of pc performance/characteristics? Advantages/disadvantages comparing with standard bench meters?
Any opinions about this?

[Kiriakos GR]

Your confusion is justified, they look like PC cards, but they are not.

Those are modular = there is a mother box,  and it can host many of those.

Why some one to need them?  In the industry we use single current sensors (ring type) so to measure Amperes, the output of those sensors are few mV. 

By adding many of those cards you can monitor many cables at the same time, and you can build your own alarm system against overloads. 

[Phyllomedusa]

Well, advantages are mostly that it's interchangeable (fast) and modular. Take your PC with labview or sth. else and keep it running.
For that reason, it is nice if you need a lot of data (logging), want to process the data (for example the temperature drift of a component under test) or for batch testing where you test a lot of components and build a rig to just plug them in...or just fast measurements.

....so you see, it's not just the USB device, it's also the Software. They are pretty accurate, but not as accurate as a really good Benchtop Multimeter. The PC has less influence, but depending on your needs you may have problems with USB data rates or so. Not a concern for private users I guess.
We use some of these (Redlab....much cheaper and OK, Multichannel) to log data on our Ground Truth and Profiling Station. We opted for a USB device because we can readout the Sensor with a voltage output, calculate the data and statistics from that reading and store it on a PC as backup and send the data to our Server for further processing.

For normal use and experiments, it is nicer to use a Benchtop. Often they offer a USB or GPIB option so that you can connect the Benchtop meter to your PC for automated measurements. Then you'll have more or less the same as that USB device but not that fast.

There are also stand alone System which are modular like a USB setup, but don't need a PC. Have a look for that VXI, PXI, LXI Stuff..... pretty interesting stuff, but expensive and too much for normal needs