Keithley 2182A for long duration voltage reading

[CaptA]

Hi,

I wanted to make noise measurements of a system with a Keithley 2182A by doing a voltage acquisition for a given time and then doing the analysis.

For that I need to read voltages with the 2182A for a set amount of time and each readings need to be made at a constant time interval.

Does anyone know how I could do this ?

[Minions]

You need to read the manual on triggering.  It can be set to read either an internal or external trigger.  This can all be handled through SCPI programming of the instrument.

[CaptA]

That's what I was thinking off but I don't really understand how to use the triggering functions.

If I set a Trigger with time as the internal source, it will do as many measurments as I asked and then i just have to use the :FETCH ? command?

[cstorey]

You have 2 options,

A - you can use the instrument buffer to record up to 1024 readings

B - do single readings and then the total number of readings is unlimited.

As Minions suggested, you will need to look at the triggering.  I'd recommend using the timer trigger if you go with option #A.  Just make sure your interval between readings is longer than your integration time by 2-3x at least if you use auto-zero, auto-range, etc...  (i.e. If you use a 0.1s integration use a 0.5s timer between readings.)  There are lots of little delays in the actual measurement, and noise is increased if you try to read too fast without accounting for those delays.

Option A has exact timing, controlled by the instrument.  Option B timing can be done either by trigger source or by the PC bus and you will need to read/calculate the time as you measure.

[CaptA]

I think it would better to do option A, but I have been trying to test the triggering functions and I don't really get it, I will do some research.

 Thanks

[cstorey]

Are you using LabVIEW?  There's a 2182 driver and an example included with reading from the instrument data buffer.  You can use that example as a starting point, add triggering (timer) then make the delay long enough to collect all data before reading it back.  Something like..

Since I haven't read the manual and don't have this voltmeter this code is undebugged.