Can labview programming take different measurement simultaneously on DMM?

[pidot97]

Hi, I am a student, and new on labview. I want to know can we code labview to take different measurements simultaneously on DMM. As an example, I want to take voltage and temperature simultaneously. I'm using Keithley 2000 multimeter. If can, how do we code the program?

[crossrulz · Accepted solution]

Simultaneously as in "at the exact same time"?  No.  It is a limitation on DMMs, they can only take 1 measurement at a time.  You can write a program to take a voltage measurement and then take a temperature measurement as quickly as possible.  A better route for you would probably to use a DAQ that can take the measurements a lot faster.  Even if the measurements are not simultaneous, they are fast enough that it won't really matter for what you want (definitely faster than the DMM route).

[GerdW · Accepted solution]

Hi pidot,

I want to know can we code labview to take different measurements simultaneously on DMM. As an example, I want to take voltage and temperature simultaneously. I'm using Keithley 2000 multimeter.

To answer that question you have to read the manual of your Keithley DMM: either it supports your requirement  or not…

If can, how do we code the program?

Learn LabVIEW.

Install the Keithley2000 device driver you will find in the IDNet.

Check the example coming with the device driver.

Apply your knowledge from reading the manual to create a VI according to your requirements…

[kaba2005]

Hi,

is it really neccessary to read voltage and temperature simultaneously? For most applications the temperature in changing relative slowly. Even if you acquire data with a delay of 2 or 3 seconds, it won't matter.

Regards 

Kay

[cstorey · Accepted solution]

Some electrometers (fancy DMMs) measure temperature with every reading but not the Keithley 2000. With the 2000 you either wire the thermocouple to the front/rear inputs and your voltage measurement to the opposite input or alternately you can use a switching card with thermocouple on one channel and voltage measurement on another.  Even with the switch card you need to reconfigure the DMM to first measure voltage on one input and temperature on the other.  Switching channels takes ~1-5ms, re configuring the measurement setup about 30ms. 

There are trade-offs to be made in all measurement setups.  Lets say you could measure temperature, switch channels and resetup the DMM and measure voltage 50-100ms later.  Close enough to simultaneous? 

But if you are measuring a 1mV signal and want 1nV accurracy (here you need auto-zeroing, auto-settling, some averaging, etc.. which makes the voltage measurement slower) then it will be more like 2-3s between temperature and voltage readings.  

All depends on what your requirements for *simultaneous*.  The code to do the measurements is pretty simple and we can help if you get stuck.  (Post your attempt here after looking at driver examples.)