SWEEP Keithley

[BENIO]

Hello Guys,

I am using LV8.2 and I have built a SWEEP program for the Keithley 2400 .now I would like to aquire also voltage from HP DMM 34401A while sweeping with Keithley after every step.I need to see a comparator output toggling while I sweep a current.Thanks for your help!

[ThiCop]

Hello,

There's an NI Certified Instrument driver available for the HP 34401A (actually there are 2), so the acquiring of the voltage can be done by using one of both. Because you're using LV 8.2 you should choose the driver compatible with LV 8.0.

Do you mean that the comparator output should be connected to the acquired voltages?

Can you upload you code (or a part of it), so that I'm able to explain more detailed what you should do in your case?

[johnsold]

You may need to generate the sweep in your own code rather than using the sweep in the Keithley driver.  Calculate the voltage versus time values you want to generate.  At time t(i) write the voltage v(i) to the Keithley.  Then read the DMM and do your comparisons. At t(i+1) repeat.  This will only work if you have time to Write to the 2400 and read from the DMM between t(i) and  t(i+1).  If you need to sweep and measure faster than that, you probably need a different set of instruments.

Lynn 

[BENIO]

Hello Thierry,

I am using the sweep vi from Keithley in the SWEEP and Acquire measurement vi.So in the configure output sweep vi. I should insert the Volt acquisition VI from HP34401A in order to measure voltage for every step and insert a delay in between this untill the comparator output settles.

I n fact I need to generate a magnetic field and see the output toggling, so I need some delay between each I step.

Do you think it is possible?or should write myself an own code as suggested by Johnsold?

Thanks to answer.

[James_W]

As Lynn suggested, write the code yourself.

That way you can remove all the extra junk that the drivers include that you don't need and you can increase your acquisition rate if required as you can optimise your code.

(Generic drivers are never optimised for speed, they are optimised for flexibility).

James

[ThiCop]

As Lynn and James suggest the best way to guarantee that your code behaves like you want it to behave (and is optimised for speed) is to write the code yourself.

[ThiCop]

Hello,

So did you succeed in writing it?

[BENIO]

Hello Thierry, Sory to answer that late on your question. Yes I did write the code. would it be easier to use LabVIEW Signal Express to generate that sequence? Do you know where can I find the IVI for the KE2400?

[tbob]

Don't use Signal Express.  What you want to do is quite easy.  You want to set a voltage on the 2400 and then read it with the 34401.  Then repeat the cycle with a new voltage.  Technically it is called a sweep, but you don't need to use the sweep functions and you don't need to generate a signal.  It is very simple:

Initialize both meters.  Create a while loop.  Put in the Keithely write inside the loop followed by a Agilent read.  For the voltage setting you will need a shift register on the loop borders.  Initialize the register with your starting voltage.  Wire this to the Keithley write.  Use the Add function to increment the voltage value and feed the sum to the right side shift register.  Use a compare, like greater than or equal to, to stop the loop when the voltage reaches your stopping point.  Try coding this yourself.

[smercurio_fc]

Or, you could just do this:

 

Message Edited by smercurio_fc on 06-10-2010 01:28 PM