Keithley 2182 NV Fast Response Problem !

[becidea]

Dear All,

 I am using K2182A nanovoltmeter for my experiments. I wish to use both channel one after another. But the time delay between these two measurements are very high. I don't know the reason but I also couldn't not make a single voltage measurement using ch1 fast.

I attached the vi I am using. I am looking forward your response.

best.

[johnsold]

I do not have the Keithley subVIs, but I suspect that the name of the subVI "Keithley 2182 One Shot Measure-ch1-ch2.vi" may be a clue. One shot measurements on many instruments are the slowest way of making measurements. Also doing a hard reset and GPIB Clear on each call is likely very slow.

GPIB instruments generally are not fast at switching channels, changing ranges (autoranging), and so on. If the instrument is capable of configuring the two channels for different types of measurements and then reading both channels together, that may be faster.

Set up a VI which does all the configuration. Then put a two-channel read in a loop. After the loop ends, do the Clear.

Using the VISA functions are generally preferred to the lower-level GPIB functions unless there is a specific reason to do so.

Lynn

[becidea]

Hi,

I measure at the same time but I also don't know simultanous measuremen of Ch1 and Ch2

I attached a library of K2182. There is "one shut measurement". I am measuring temperature by ch2 and voltage ch1. I made one vi with case struture. both vi I added to be chosen.

Can you give an example which explains your idea. I mead how to do that, then i will apply to my vi

best

[becidea]

Hi,


I am using MEASure and READ commands but both of them are very very slow.

I also have K182 -old one- G0X command is very very fast to read. As soon as you send command, you read the voltage.

I am asking any advice to read as fast as possible.

Best.

[amezam]

Hello Becidea,

I’m linking the User’s Manual for the Keithley 2182 Nanovoltmeter. I would like you to check the following sections:

-          Programming Example on page 2-21, which describes how to do a measurement for voltage CH1 and temperature CH2

-          Delay Information on page 7-4, you could check if there’s a delay enabled or if it could be the nominal delay it takes the relay to settle before making the measurement

-          Examples Section on page H-5, the first one is called One-Shot Reading, DC Volts, No Trigger, Fastest Rate. You could try it and check if you keep getting this behavior.

Check if you are able to do faster measurements with the device following their instructions. You could also try posting on Keithley’s forum for support regarding this device.

Best Regards,

Alina M

Applications Engineering

National Instruments 

[johnsold]

Becidea,

You have mentioned "fast" and "slow" but have not given any quantitative data.  How fast do you need to read?  How slow is too slow?

Thanks, Alina, for the link to the manual.

Lynn 

[becidea]

Hi Johnsold,

Slow means about 3 sec for each measurements-that is in my system-, and also 3 sec delay between two measurements of voltage and temperature.

Fast means les than sec.

Best.

[johnsold]

The subVI "Keithley 2182 One Shot Measure-ch1-ch2.vi" is not in the kei2182 LLB. There is a one shot VI there but it only reads one channel.

After looking at the manual and the rest of the program, I notice that the Aperture appears to be set to 1 second.  It also looks like the command to set the aperture does not follow the syntax as shown on page 14-9 of the manual.

After reading Alina's suggestions and the specifications, it appears that you may need to do some fine tuning of the program to make sure that parameters are set to the fastest values. NPLC, aperture, filter, digits, and possibly others can have significant effects on speed.  It may take some time to find the combination of setting which produce the best compromise between speed and accuracy for your application.  And really only you can do that.

Lynn

[becidea]

Thank you very much for your advices.

I will check the parameters and try to see which one gives me the best result

Best.