Keithley 2450 – Can’t read Voltage and Current in one SCPI query (firmware 1.7.3c)

[gva]

Hi everyone,

I’m using a Keithley 2450 SourceMeter (firmware 1.7.3c) and controlling it remotely via SCPI commands (through VISA).
My goal is to source a current and acquire both voltage and current in a single read operation to improve sampling speed.

However, I’ve run into a problem:

*RST :SOUR:FUNC CURR :SOUR:CURR 0.01 :SENS:FUNC "VOLT" :FORM:ELEM VOLT,CURR :OUTP ON :READ?

At the :FORM:ELEM VOLT,CURR line, the instrument throws
ERROR -113: "Undefined header",
and as a result, :READ? only returns one measurement (depending on the last selected sense function).

When I use two separate queries like this:

:SENS:FUNC "VOLT"; :READ?; :SENS:FUNC "CURR"; :READ?;

…it works correctly, but it slows the acquisition by about 2.5× — defeating the purpose of simultaneous measurement.

I also tried:

:SENS:FUNC "VOLT:DC","CURR:DC" → ERROR -1129 ("Command needs 1 parameter") :SYST:LANG SCPI2400 → ERROR -113 :READ?; :FETCH? → two identical (current-only) results

So it seems that on firmware 1.7.3c, the 2450 might not support multiple sense functions in one command — or perhaps I’m missing the correct syntax.

My question:
Has anyone managed to configure the 2450 to source current and measure both V and I in a single SCPI query?
If yes, could you please share the correct command sequence or a working example?

It would also be helpful to know if this behavior differs in later firmware versions.

Thanks in advance for any insights or test feedback!

Best regards

[santo_13]

Please check the instrument manual if that is even possible, I bet it may be because it has only one ADC that mux between the current sense and voltage sense modes and hence you can read only one at a time and you lose performance due to the switching alternating measurements.

I recommend reaching out to Keithley tech support to check if the hardware and firmware allows one to simultaneously measure both voltage and current.