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Keithley 2401 limiting a 2400 to 21 V when working together

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DrPiotr
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Keithley 2401 limiting a 2400 to 21 V when working together

Post by DrPiotr » August 1st, 2014, 7:31 am

Hello,

we are trying to write a VI for controlling a few pieces of equipment for transistor characterisation. A low voltage 2401 (21 V max) is to be used to measure gate leakage current only, whereas a 200 V Keithley 2400 is meant to source/measure drain current. However, the 2400 is not allowed to go above 21 V, which is the max voltage for the 2401. I believe that the low voltage 2401 is limiting the more powerful 2400. I will greatly appreciate help on this issue.

Dale C
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Re: Keithley 2401 limiting a 2400 to 21 V when working toget

Post by Dale C » August 6th, 2014, 8:43 am

The Model 2400 can output up to 200V. But only to 100mA.
Usually, the 21V limit is because the current compliance is set to higher than 100mA, possibly on the 1A range.
This also is true for the current compliance and the current measurement range.
So try to set the current compliance and current measurement range to the 100mA on the 100mA range.

DrPiotr
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Joined: March 6th, 2014, 5:58 am
Country: United Kingdom

Re: Keithley 2401 limiting a 2400 to 21 V when working toget

Post by DrPiotr » August 7th, 2014, 1:38 am

Thank you for replying. On the 2400 I have the compliance and current set both to 10 uA, whereas on the 2401 it is 1 uA for both. Despite this, I still get an error :(

Dale C
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Re: Keithley 2401 limiting a 2400 to 21 V when working toget

Post by Dale C » August 7th, 2014, 6:29 am

OK, so this is not a range compliance issue or current compliance issue.
Odd that one unit is limiting the other.
Can you post a diagram?
And maybe the code?

DrPiotr
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Joined: March 6th, 2014, 5:58 am
Country: United Kingdom

Re: Keithley 2401 limiting a 2400 to 21 V when working toget

Post by DrPiotr » August 7th, 2014, 6:39 am

Now I think it might not even be a Labview issue. The same thing happens when I operate both SMUs just using the buttons on their screens (right after turning them on and not Labview). They are both connected to a computer via a double RS-232/USB cable. What do you think?

Dale C
Keithley Applications
Keithley Applications
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Re: Keithley 2401 limiting a 2400 to 21 V when working toget

Post by Dale C » August 7th, 2014, 12:30 pm

Not sure what the double RS-232 connection is doing.
I would disconnect it from each unit and try from the front panel your application.
I would not expect anything different but you never know.
After you try that, disconnect the 2400 from the 2401.
See if the 200 can output the 200V. Do not forget about the 100mA limit for greater than 22V.
If it cannot, then the unit has some service issue.
If it can then there is some interaction with 2401.

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