GPIB control of SR830 lock-in : read/write problem

[aa35]

Hello,

I am having trouble  communicating the Keithley 6221 and SR860 lock in . Could you please share the code. 

email: aryalanil90210@gmail.com.

thanks

[Albert.Geven]

Hi

I'm willing to share what I have but maybe a better approach is to send what you are trying to accomplish.

So share your code as a vi, not a picture and I compare it with what I have and know.

[aa35]

Hi Albert,

Thanks for the reply. I am new to Labview. I am using Keithley 6221 to source ac current  and  SR860 lockin amplifier to measure the voltage. I have managed to make the block diagram (very raw) for the Keithley 6221 and SR860 lockin from the example and device drivers. The two devices are communicating. What i need to do in general is to set a value of current frequency and measure the voltage using lockin amplifier.   Then repeat it for different  frequencies. So I would like to modify my block diagram such that: 

1) i can input the frequencies as f_max, f_min, and in steps.(say fmin = 1 Hz, fmax = 100Hz, step =2 Hz)

2) and corresponding to each frequency value the lockin measures the voltages, and move to new frequency and so on until it reaches fmax.

3) be able to save the data  (frequency, voltage ).

I have attached the lab view file (again its very naive way).

I appreciate for your help.

Thanks

[Albert.Geven]

Hi

Please start your request in another topic, because this is unrelated to the original topic.

Tell me also which drivers you use and (links to the drivers)

And your example shows what to do.

Do you know you can save your vi with default settings?

In LabVIEW go to Edit/make current settings default and after that save the file.

In essence you have to modify the frequencies e.g. in a while of for loop

wait to stabilize and then measure and save the result for each item.

So after initializing both instruments enter a while loop

in that while set values, stabilize, measure 

next while loop do the same for the next value

until all values are done.

After the loop write the results to a text file.

the only needed flat sequence struct is the one with the wait, the others will be settings and meas vi's of the correct instruments

[YH_Huang]

Unlike a lot of guys here who naively suggest you to simply use whatever vi drivers available from instrument vendor/NI and solely rely on it, It is much better to carefully read the manual of each instrument and open the available driver vi to see the command and structure as an example.Built your own driver vi base on SCPI or whatever commands defined by vendor on manual and use VISA Write/Read.

I hate to say this, but vi drivers of keithley SMU/DMM/Current source(as well as instruments from other brand...) contains a lot of subtle bugs, some of them are typos in SCPI commands, some of them are strange data transfer structures which cause conflict condition(which make debugging really difficult...). Also, if you want to push the performance of your instrument to its designed value, those vi drivers won't help, they typically contains a lot of junk structure to slow down the operation, or just not include commands need to push the limit.

Maybe there are some really well written driver vis, but it definitely not something you can find on download page from NI, just use them as reference.

[Albert.Geven]

Hi Huang

Not to forget the number of updates in Keithley software in the instruments that are part of the reasons that instrument drivers behave differently on different machines with the same product ID but different updates.

And also not to forget the the SR830 is an instrument that is famous for its bad software architecture.

Instead of just blaming the drivers did you report those issues to the people trying to improve the NI-drivers?

I'm not really enthouiastic about the effort from within NI, but when I email them I almost always get a respons and see improvements in their drivers.

Their address is instrument.drivers@ni.com