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:READ? return in simultaneous voltage and current measurement

Posted: January 11th, 2019, 4:39 am
by JeanSu
Hi everyone,
I have a Keithley 2410, which I address using my own Python program. I am applying a fixed voltage and want to measure the real voltage (not the set one) and the current. The problem is that I do not understand the returned values from the :READ? command.

Code: Select all

WRITE: ":SOUR:FUNC VOLT"
WRITE: ":SOUR:VOLT:RANG:AUTO 0;:SOUR:VOLT:RANG 20"
WRITE: ":SOUR:VOLT:LEV 0.5"
WRITE: ":SENS:CURR:PROT 1
WRITE: ":FUNC 'VOLT', 'CURR'"
WRITE: "OUTPUT ON"
WRITE: ":READ?"
Return value: +4.998975E-01 (the applied 0.5V),+4.992652E-03 (current over 100Ohm resistor) ,+9.910000E+37 (?),+1.346539E+04(?),+2.355600E+04(?)

Does anybody know what these values stand for or where I can read about the return value? I already looked through the UserManual but didn't find anything.
Thanks in advance for your help!

Re: :READ? return in simultaneous voltage and current measurement

Posted: January 16th, 2019, 5:37 am
by Andrea C
You can send a format command for which data elements should be returned in response to the ":READ?" command.

Default is:
:FORM:ELEM VOLT,CURR,RES,TIME,STAT

If one of the parameters is not measured, e.g. resistance in your case, but is still in the format specifier for return, the instrument will report 9.91E37 to indicate not a number (NAN).

Re: :READ? return in simultaneous voltage and current measurement

Posted: January 29th, 2019, 1:01 am
by JeanSu
perfect. thank you for your answer!