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Triggering 2182A with 2602B

Posted: May 21st, 2015, 9:39 am
by Mathis
Im having trouble making a simple 4-point measurement setup with a 2602B (in 2400 emulation mode) sourcing stepped pulsed current, and having the 2182A measure the voltage. This system will measure the IV characteristics of superconductors, so I need the two to work via trigger. To source current up to 10 A I need pulses less than the 1.8 ms required by the 2601B. I'm trying to set them both up is SCPI since the 2601B is replacing a 2440.

The problem is that the original LabView VI written by a colleague of mine did not use the trigger, but instead just turned on the source, measured, and turned off the source. This means that the source is on for ~ .5 seconds, which is limiting us to 3 A DC with the 2601B.

I found an example trigger with two 2400s set up with triggers to take measurements, but both of them also act as a source. Link I tried to manipulate this code, a lot for the 2182A I think is unnecessary given that it does not source, but only measure. Also, I'm guessing that the trigger sequence will be slightly different.

I need the 2601B to source current in stepped pulses of 1.8 ms with a duty cycle of less than 1% and measure the current output. During the pulse, I also need the 2812A to measure the voltage. I'm guessing after the delay for the 2601B I need a trigger to the 2182A measure (sense).

Here is the SCPI code that I currently have from the VI. All of the code is in order of execution. I'm interested in knowing how to make this trigger work between these two units. I'm not very familiar with SCPI at all, and any help with this would be much appreciated.

:*RST; -- reset
:TRIG:CLE; -- clear triggers
:SYST:azer on; -- ensure auto zero
:form:elem curr; -- send out only current
:sour:cle:auto on; -- auto output on
:sour:cle:auto:mode tco; -- output off after trigger count

:*rst; -- reset

:arm:coun 1; -- perform 1 sweep per init
:arm:sour imm; -- immediately go to trigger layer
:arm:dir ACC; -- wait for trigger event
:arm:outp none; -- no outputs triggers from scan
:trig:coun 10; -- # of points in sweep
:trig:sour tlin; -- trigger via trigger link (will this work for trigger link from 2182A to 2601B digital i/o?)
:trig:dir acc; -- skip first trigger (why do I want to skip first trigger?)
:trig:outp del; -- output trigger after delay
:trig:olin 1; -- output trigger line (:trig:ilin 1; wont work for 2182A?)
:trig:del 0; -- trigger delay

:trig:sour ext; -- (:trig:inp sense; would not work. I am trying to receive trigger to measure.)

:sour:func curr; -- output current
:sens:func ‘curr’; -- measure current
:sour:curr:star 0.001; -- sweep start point
:sour:curr:stop 0.01; -- sweep endpoint
:sour:curr:step 0.001; -- sweep step size
:sour:curr:rang:auto on; -- autorange current
:sens:volt:rang:auto on; -- autorange voltage
:sour:del .01; -- set source delay
:sens:volt:prot 2; -- 2 V compliance
:sens:volt:nplc 1; -- nplc
:sour:curr:mode swe; -- perform sweep

:sens:volt:range:auto on; -- autorange voltage

:read?; -- take measurements

Re: Triggering 2182A with 2602B

Posted: May 21st, 2015, 12:35 pm
by Dale C
All this is good. But one thing.
The Model 2182A would not be able to make the measurement in 1.8msec.
The fastest the model 2182A can make a measurement is about 10msec or 100 per second.
So the 1.8msec pulse with have come and gone by the time the 2182A can measure.

Re: Triggering 2182A with 2602B

Posted: May 21st, 2015, 1:39 pm
by Mathis
Thanks for the quick response Dale.

Do you have any suggestions for what equipment could handle an IV measurement of a superconductor at up to 10 A? The maximum expected volt on the entire load is only 0.1 V with a 10 A source, but the voltage across the superconductor is on the order of micro volts. We have used the 2182A before to measure these small voltages with both a 2420 and a 2440 used as a DC current source, pulsed for about 250 ms. We would ideally like to reduce the pulse length as much as the nanovoltmeter will allow us, in order to reduce the power though the PCB superconductor mount in the cooled magnet . Since the sample space is cooled (usually at or below 20K) and there is a very small expected voltage, is there a SMU that can source 10 A with a pulse at about 10 ms?

Re: Triggering 2182A with 2602B

Posted: May 22nd, 2015, 5:31 am
by Dale C
Model 2651A could give you a 10A pulse for 10msec.
The data sheet is attached. Look at page four for this type of information.