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Trigger models in 2450 vs 2600 series or 4200 SCS

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shyamu
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Joined: February 15th, 2020, 2:42 am
Country: Sweden

Trigger models in 2450 vs 2600 series or 4200 SCS

Post by shyamu » February 15th, 2020, 3:12 am

I have an application for which I now use the Keithley 2450 SMU as follows: I increase the set voltage in steps and measure current after each step, checking that the current is below a certain limit (specific to that particular voltage). If the current exceeds that value the output is turned off immediately. To achieve the fastest response time, I use a TSP script and have programmed the voltage stepping, and current limits into source and measure configuration lists and the entire logic is built into trigger model blocks. This works nicely, and every step-measure-check cycle takes about 450 ms.

Since the Series 2600 SMU can measure at even lower NPLC than the 2450, and can store reading to buffer using TSP scripts at least twice as fast as the 2450, I wanted to try and program a trigger model in the 2600 series that can do the same job--but faster than 500 ms. But I realised after reading the manual that the trigger model in the 2600 series is organised very differently, and does not have the trigger.model.setblock() with the various functionalities available in the 2450. For instance, I could not find how to do limit testing of current and take an action accordingly. I must say that I have no experience working with trigger models in anything other than the 2450.

I also have access to a 4200 SCS , and a cursory glance at its reference manual also led to the same conclusion as the 2600 series. Does anyone know whether programming a trigger model to do what I have described above is possible using a 2600 series or 4200 SCS ? If yes, can you point me to the functions that can help, or even better to example code blocks? Thanks a lot!

Andrea C
Keithley Applications
Keithley Applications
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Re: Trigger models in 2450 vs 2600 series or 4200 SCS

Post by Andrea C » February 21st, 2020, 12:17 pm

The trigger model of 2600B Series are quite different from the 2450.

The trigger blocks based implementation of 2450 has easy to implement support for exit on compliance (on event block).
The 2600B will be quite a bit different.

A couple questions:

Can you confirm that your 2600 model is either an A or a B vintage? The original 2600 without any letter suffix will be different yet again.

For the 2450 code that you have working, is it each source and measure operation that is requiring 450msec? That seems quite slow.
Or is it the entire sweep of N points is ~450msec?

shyamu
Posts: 2
Joined: February 15th, 2020, 2:42 am
Country: Sweden

Re: Trigger models in 2450 vs 2600 series or 4200 SCS

Post by shyamu » April 1st, 2020, 8:29 am

Hi Andrea,

Thanks for your response! The answers to your questions:

1) The 2600 series model we have is a 2602B.

2) There was a typo in my original post: I mean to write 450 micro seconds and ended up writing ms. So the time been consecutive "measure current" > "check current is below limit" steps is 450 microseconds using the 2450. If the voltage sourcing level is changed as well it takes a bit longer ~ 760 microseconds. I have source readback off. I do not know exactly how fast the source

Do you think I can get faster loop times using the 2602B?

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