Hi. I’m Bill Griffith, an application engineer from Agilent Technologies, and today we’re
going to be doing some USB data logging and we’re going to be using the 34972 and three
different methods using USB to log data. So let’s start with using a USB cable that’s
connected to the rear of the 34972 and we’re going to connect it to the PC. I’ve already
downloaded two pieces of software from Agilent Technologies, the Agilent Connection Expert
along with Agilent’s BenchLink Data Logger software. Both are free and can be downloaded
from the 34972A Web page. I’ve installed them on the PC and I’ve gone ahead and opened
the BenchLink Data Logger software.
To set it up, I’m going to start with the tab the furthest to the left which is Configure
the Instrument. So from here I can go ahead and add my instrument, which I’ve already
done. I can move on to the next tab to configure the channels. So in the first channel, I’ve
hooked up a thermistor. The way the Agilent 34972 works is it uses a universal channel
and so I can connect my DUT or sensor to any channel and then in the software go ahead
and select what type of voltage or resistance or frequency I should measure on that channel.
And again, I have a thermistor so I’m going to scroll down and pick a 10K thermistor. So
this channel is configured.
My next channel is just a straight DC voltage, so I’m going to keep the defaults.
My third channel is also a DC voltage but I’m going to scale this channel and so I’m
going to go across here and I can enter a scale value of 37.5 and an offset of -37.5. Since
I’m no longer measuring in straight DC volts, I can also change my label to be something
that makes more sense to my measurement, so I’ve gone ahead and made that change.
From here, I can go ahead and then set up my scan on the next tab and so we will go ahead
and set up our scan for three seconds and I’m going to go ahead and scan continuously
until I choose to stop. All right, we will go ahead and start the scan and then finally
we can bring up our last tab which is a graph, so in real time, we’re actually going to
see our data plotted so you can make sure that everything is going well with our data
logging. And when we get enough data, we can go ahead and stop our scan. So all the data
is now on the PC, so we’re able to share the data. We’re able to document the data
very easily with the BenchLink Data Logger software.
The second method of USB data logging we’re going to do is to combine using the BenchLink
Data Logger along with our USB stick. So let me go ahead and insert our USB stick. One
of the really nice features of the BenchLink Data Logger software is it makes it easy to
set up a lot of channels, so if you’re using a lot of channels, it makes sense to use the
BenchLink Data Logger software. And in the case of having the PC not near the instrument,
using the USB stick can really help transfer that configuration over to the 34972.
So let’s go ahead and save the configuration that we’ve set up on our BenchLink Data Logger
software. So I’m going to go ahead and create a configuration file. It is asking about the
format that we can save the data to the USB stick once it is plugged into the 34972. So
it has the capability of if you go over the file size of 64K bytes, of breaking the file
into smaller pieces. This was important for older versions of Excel that can only take
a file size of 64K or less. In addition to that, we get to set a delimiter. I’m going to
choose comma separated delineation which is good for Excel.
So now I’m going to go ahead and save my configuration file. I’m going to save it to the USB stick.
Okay, go ahead and overwrite the one I currently have. So once we’ve saved our configuration
file to our USB stick, we can remove it from the PC and transfer it over to our 34972.
We will go to the USB drive menu and here we can select to log the readings to the USB
stick, which is enabled. Another choice is we can export the readings that are in the
nonvolatile memory to the USB stick. We are not going to do that. We can change the format
of the readings. This is we’re we get to set if we want to break it into small files
or just keep it in one large file and also the comma separated delineation.
But what we want to do is we want to import our configuration. So I’m going to go ahead
and select that. I’m going to change the file name to our configuration file. So now the
34972 is configured from our USB stick that we downloaded from the software earlier. So
from here we can go ahead and start our scan from the 34972. So I’m going to go ahead and
start a scan and one of the nice features is I can actually monitor the individual channels
to make sure that the data we’re collecting is correct and while I’m monitoring these
channels, it does not affect the scan that’s in progress. I can even go in and view the
readings in memory all while the scan is in process so this does not affect the scan in
any way. So once the scan is completed we can stop it and now our data is on our USB
stick and we can bring it back to our PC.
Our third method for USB data logging is to set up from the front panel. So this is a
good thing to do when we don’t have a lot of channels. So for our current example, we
only have three channels so we’ll go ahead and set it up from the front panel. So we’ll
start by configuring our first channel, which is again, a temperature measurement. So we will
go ahead and select temperature. We will select thermistor and we will also select 10K ohms.
So that channel is set up. We will measure degrees C with .1 degree resolution.
Moving on to Channel 2, we will accept the defaults as just a DC voltage measurement
and Channel No. 3 is also a DC volt measurement, so we will accept the defaults but I do want
to add scaling, so I can do that from the front panel. We’re going to set a gain. Itís
already programmed in at 37.5 and we’re going to set an offset. Again, itís already programmed
in -37.75. We will set a label that’s a little bit more meaningful. Once again, itís programmed
in. Great. So now our channels are configured.
We could go ahead and set an alarm from the front panel but we’re not going to do that
for this video. Instead we’re going to go ahead and jump to our scan interval, so we can go
ahead and set our scan interval up. So we can select how many seconds between scans.
I’ve selected three. I’ve also selected continuous, so will continue to make measurements
until we stop it. So now we can start our scan. So now we’re scanning every three seconds
and the data is being stored in our USB stick.
Another nice feature about the 34972 is if you lose power because of a power failure,
the unit will come back up and as soon as it comes back up, it will start data logging
again. And the nice thing about it is that all the readings are time stamped so itís
easy to identify that gap, so you have your data before the power failure and your data
after it and you will have that gap in between with the time stamps.
So let’s go ahead and stop our scan now. Okay and we can go ahead and remove our USB
stick with our data on it and we will go back to the PC. I want to show you what the files
look like on the USB stick. As you can see, it saves both the data file and it also saves
the configuration. So if you open it up, you can actually see the type of hardware that
was used to make the measurement and so that you can recreate it easily.
The second file is the one that actually contains the data. Last night I took some data, so
I set the scan to happen every one minute. I measured both the temperature and the humidity
and from that I was able to create a graph. So you can see the temperature falling. It
started at 80 degrees Fahrenheit and dropped down to about 70 and during that same period
of time, the humidity started at about 35 percent and rose to just over 50 percent.
So in summary, thereís three different methods to use USB and data logging with the 34972.
If you have lots of channels and the PC is close to your 34972, use a direct connection.
If your data acquisition box is remote, you can use the USB stick to configure your 34972.
And finally, if you just have a couple of channels, it is really easy to set up from
the front panel and capture your readings on the USB stick and then bring it to your
PC and upload it into common applications such as Excel.
So I hope you found this useful. Thank you very much.