Application with Keithley 2260B-30-36 and Keithley 2701+7700

[DieLiz]

Hi All,

I have a Keithley 2260B-30-36 and a Keithley 2701+7700. I'm writing a code with LabVIEW 2018 and I need help for coding my application.

My application:
With the 2260B power supply I want to apply a voltage and a current to a 'resistor' controlling the voltage, in the meantime the 2701+7700 should scan 3 channels, save the voltage readings into the buffer, then read the data and plot them. While I ramp up the voltage (with a 2260B test sequence) I need to read the voltage across a shunt resistor (to calculate the exact current flowing thru) and across the 'resistor' (to measure the exact voltage across) with the 2701+7700. The voltage should ramp up to about 10/11V as fast as possible, stay at 10/11V for 3 seconds and shut off. The 2701+7700 should start the voltages readings simultaneously with the 2260B test sequence.

So far I was able to communicate with both instruments via ethernet and run the VIs examples founded into the LV drivers. The instruments communicate without errors and execute the code correctly. 

Next steps that I need help with:
-fig out how to load/run the test sequence into the 2260B.
-create one VI with both instruments and synchronize them together.

My idea so far:
-to load the test sequence into the 2260B I was thinking to use the USB drive with a .csv file. Do you know if and how I can do that directly with LV?
-to synchronize the beginning of the 2260B test sequence and the 2701 scan (of 3 channels) I can see to way. (1)Use an external I/O signal from the 2260B into the 2701 or (2) synchronize the instruments via software. Which one would be more precise and easier for me to fig out?

I would really appreciate any suggestion and would be happy to share my code once i'm done. Let me know if you need my code written so far or any other information from me.

This is my first LV application and even if its not easy, I'm having good time to figure out this big puzzle. FYI my experience with LV is limited to a Core1 self-thought online training and an online Instrument Control training. Any suggestion and help are greatly appreciated! 

[Gregory]

I just glanced through the programming manual for the Keithley 2260B and I didn't see anything about loading a test sequence, so it seems like you have to do that through the front panel of the instrument. However, you should be able to use the LabVIEW drivers to set voltages instead of using the test sequence. 

You can use the error wire between VIs to make sure that you first set the voltage and then take your measurement. This will be slower than if you had some hardware trigger between the two instruments and you could set one to record while the other sweeps, but it may be fast enough.

[DieLiz]

Thank you for your feedback Gregory. 

The 2260B has the test sequence, I've been using that function manually. I create a .csv with a spreadsheet, load it into the power supply and run it. I would like to be able to load and run a test sequence with LV. 

I'm trying to figure it out a SW trigger or an analog trigger because the sequence has to start simultaneously with the sweep. 

[cbutcher]

Looks like I replied to a comparatively old thread! Copying here since I expect this is the better location for an effectively new question... 

Sounds like a State Machine might be helpful for you.

If you have a csv with a series of settings and timings, you can certainly load that into LabVIEW and step through them as needed. I'd suggest parsing the csv to an array of clustered values (one cluster per set of settings and timings, so probably a row in the csv). Then use a for loop or similar to go through them.

For synchronisation, a hardware circuit/pulse will be more accurate but probably also more complicated. How accurate do you need to be? Probably you can get within milliseconds using software. If they have external trigger settings it might not be too complicated to use those though and I'd guess more precise.

[Gregory]

---

@DieLiz wrote:

The 2260B has the test sequence, I've been using that function manually. I create a .csv with a spreadsheet, load it into the power supply and run it. I would like to be able to load and run a test sequence with LV. 

I understand, but I did not see anything in the programming manual that suggested you could do that programmatically. You can contact the manufacturer to double check. But, it seems like you can either run your USB stick test sequence by pushing buttons on the instrument or re-create it with LabVIEW. Since you want to control the sequence in which things happen among multiple instruments, it seems like re-creating it in LabVIEW will be your best path forward.

[DieLiz]

Thank you cbutcher. I'll learn more about the state machine and post my code here. 

[DieLiz]

Thank you Gregory.

I've contacted Tektronic to find out more about it. I was actually on your same page, I'm able to run a test sequence manually but I did not find anything for doing that programmatically. Once I know more about it from the manufacturer ill post it here.

[DieLiz]

Hi folks,

I need help to merge these two VIs and synchronize the beginning of the channels scan with the start of the test sequence. 

Instrument:

Keithley 2260B-30-36

Keithley 2701+7700

Project: 

Control programmatically the 2260B and output the test sequence. In the meantime with the 2701+7700 scans the channels, store the reading and output the data on a file.

Question: how do I start the scan on the 2701+7700 at the same time the test sequence goes on with the 2260B?  

Thank you!

Diego

[DieLiz]

Hi Guys,

With the shelter-in-place order, I've had time to study LV and made some baby progress on my project. I attached the VIs here.

Now I would like to merge these two VIs and synchronize 2701 starting of the scan with the beginning of the 2260B test sequence. Do you have any suggestion for how could I do that?

Thank you.

Diego

[cstorey]

I'm trying to better understand your vague "merge" these two VIs. 

If I understand you want to perform the scan of all channels at every step in 2260 sequence?  Or do you want to just let the sequence run and repeatedly scan channels with a timestamp of the measurements?   What are your actual time delays for each step of the sequence?  (us, s, hours, days)  Can you supply an actual sequence file to examine?

Keithley provides a nice trigger model for their instruments, but implementation can get tricky if you need to rearm many times.  You can do the triggering in LabVIEW but there will be a variable delay between the two instruments.  How important is timing synchronicity?

Craig