Using Keithley 2410 Sourcemeter and Keithley 6485 Picoammeter Simultaneously

[Plasma Guy]

Hi,

I am new to LabVIEW and I am trying to write a program that will ouput a voltage sweep from 0-100V on the 2410 sourcemeter and at the same time read in the current measured by the 6485 picoammeter.  I have each Keithley box connected via RS-232 to an NI USB to RS-232 converter box.  The NI converter box is connected to my computer via USB.  In my LabVIEW, the instrument libraries that I have are "KE6485", "KE2400" and "Keithley 24XX".  I am totally unfamiliar with VISA and IVI.  The only labview device control I have experience with is NI DAQmx.   

Should I be using the functions in "KE2400" or "Keithley 24XX"?  How come there is a "Read" function in the KE2400 library but no "Write" function?  Also, is it even possible synchronize the two instruments so that I am reading in current values from the 6485 unit while at the same time outputting voltage values from the 2410 unit?

I have searched for tutorials or instructions that utilize the functions in these libraries, but I haven't had much luck finding something that I could use as a starting point for learning how to interface with the Keithley instruments.  If anyone could provide a link to a good tutorial, I would greatly appreciate it.

If it helps, here is a short description of my setup:  The 2410 is connected to an electrical lead on a device called a retarding potential analyzer (RPA) which is immersed in a radio frequency generated plasma inside a vacuum chamber.  As the voltage to the RPA is swept from 0-100V, the current (which comes from a separate electrical lead on the RPA) is measured by the 6485 picoammeter.  The current values from the RPA are expected to be on the order of picoamps.

Thanks!

-PG

[Dennis_Knutson]

I think I can answer some of your questions.

Synchronization between two instruments is usually a function of hardware. Some instruments may output a pulse that can be used to trigger another instrument. I've only briefly used the 24xx and that was quite a while ago. You should probably check the manual or contact Keithley. If the 2410 does not output an external signal when it steps the voltage, you may have to ramp it in software. For example, increment the voltage in a loop that sets the voltage and then command the picoammeter to take a reading. Keep incrementing until the voltage limit is reached.

I don't know which driver you should be using as I don't know the differences.

There are numerous write functions in the driver but they are low level VISA Writes. There is a separate Read VI because after doing a low level read, the returned data needs to be parsed and formatted.

Typically, the only documentation about a driver is what is included in each VI itself. Make sure you have Context Help turned on. As you move your mouse over a VI's icon or a control/indicator, the help window should give at least a brief description. Most of the knowledge has to come from understanding the instrument manual.

[nitad54448]

Hi

I think one possibility is to use the trigger cable connector (see the rear of the instruments); or (the one use often) the function GET on the board (group execute trigger).

regards

[Albert.Geven]

Hi

Be careful with the GET. You have to be sure that the setup times of the 2410 are met, before you read the picoamps.