Using GPIB interface with Keithley 2001 DMM. Need assistance in acquiring data from simple PV/battery circuit configuration.

[cappettoa]

I am currently running an experiment where I am trying to record data for voltage and current across a Li-ion battery connected in series with a PV panel and rectifier diode. I am trying to interface the Keithley 2001 DMM using GPIB-USB. All I want is to record data for voltage and current for x ammount of time. I have never used GPIB or LabVIEW before so I don't even know if I am going down the right path. I would really appreciate any help or guidance. Thanks. 

[JÞB]

Well first do go through the getting started exercizes that ship with LabVIEW.  

NEXT read the instructions that come from Keithley with your device.  PAY ATTENTION to Keithley's notes on interfacing with National Instruments software that are in that getting started guide.

Then check out the Instrument Driver Network  Its a good bet someone has used LabVIEW to work with that device over GPIB before you  There might even be examples!

You are going down the right path!

[pjr1121]

here is a link to the manual, http://www.mhzelectronics.com/ebay/manuals/keithley_2001_multimeter_manual.pdf  read chapter 4 for the commands you can send and what they do.

There are 2 options on how to proceed.

1. Use a for loop in labview to control the number of readings and use :READ? to perform a single measurement in each iteration of the for loop (export data using an auto-index output terminal to get an array).

2. Set up the buffer and have the meter record the values internally before returning the full buffer size.  This will allow the meter to make more measurements in a given time frame, assuming you don't exceed the buffer size.  This option requires a few more commands in setting up the buffer but will give you more resolution in your data; really depends on what your requirements are.

[Omar_II]

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@cappettoa wrote:

All I want is to record data for voltage and current for x ammount of time.

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Do you have 2 DMMs?

Are you switching the meter leads with some type of external relays?

Be careful trying to connect the meter to measure both voltage and current without doing damage to the meter (worst case) or just getting inaccurate readings.

Or are you reading the current across an external shut?

How fast do you need to take readings? Once a sec? 10 time a sec?

If you have two meters (advised) and it is required that the voltage and current measurements be taken at the same instance, for power calculations, that will require setting up triggers.

If you only have 1 meter, it will take time to switch between the two measurement. 2-3 measurements a sec.

[cappettoa]

Worst cas scenario, I have an O-Scope that can record voltage and I can use the Keithley to record the current. I want to take current readings from the Keithley every 10 seconds and take those data points and plot them in Matlab. I feel like this should be a very easy solution but my inexperience with LabVIEW is hindering me from getting the data I want. 

[crossrulz]

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@cappettoa wrote:

I want to take current readings from the Keithley every 10 seconds

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How much current?  What I would recommend is using a series resistor that you can measure the voltage drop.  I = V/R.  Something like a 1 Ohm will work really well if your current is in the mA range.

Measuring your current this way will allow you to safely switch between your voltage and current measurements in the DMM.

[Omar_II]

Every 10 sec is very do-able even with a PC running Windows.

You can do it with just 1 meter if you have some way of switching.

Or 2 meters or 1 meter and a scope.

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@cappettoa wrote:

I am trying to interface the Keithley 2001 DMM using GPIB-USB.

I have never used GPIB or LabVIEW before

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Do you have a GPIB-USB and GPIB cables to connect your meter to your PC?

Do you have LabVIEW loaded (with the VISA drivers)?

Open/Run NI MAX (Measurement & Automation Explorer)
Expand "Devices and Interfaces" and look for your GPIB-USB controler and click on it.

Click on "Scan for Instruments" and see if your meter is found.

If MAX can not find your meter, nothing in LabVIEW will!

Let us know when you have gotten that far.