Keithley 2450 Driver Error

Natan · March 24, 2026, 1:31pm

Hi SweepMe Team. I am having problems to run transfer curves using keithley 2450 as a gate and Keitlhey 2400 as source/drain. It showed an error message related with driver “Driver has axception. Value Error… not enough values to unpack (expected 2, got 1) and in the equipment “Error -113, Undefined SCPI header”. See the picture of debug. Can you help me to solve the problem?

Axel · March 24, 2026, 1:52pm

Hi Natan,

it looks like you already have a communication with the Keithley 2450 established, but it fails to interprete the returned values.

The Keithley 2450 supports multiple protocols (commands sets).

It looks like you are having trouble with SCPI or SCPI2400 command set/language.

According to the webpage of the SweepMe! driver, please try to change the command set to “TSP” in the menu of the instrument and check again:
https://sweep-me.net/device/25/Keithley_2450

If this solves the problem, I would not spend further effort in bugfixing it, becauses TSP is the recommended language. The driver automatically detects which language is used:

github.com/SweepMe/instrument-drivers

src/SMU-Keithley_2450/main.py

63f3c42ba


      
          def get_GUIparameter(self, parameter: dict) -> None:
              """Receive the values of the GUI parameters that were set by the user in the SweepMe! GUI."""
              self.four_wire = parameter["4wire"]
              self.route_out = parameter["RouteOut"]
              self.source = parameter["SweepMode"]
              self.protection = parameter["Compliance"]
              self.speed = parameter["Speed"]
              self.range = parameter["Range"]
              self.average = int(parameter["Average"])
          
          def connect(self) -> None:
              """Connect to the device. This function is called only once at the start of the measurement."""
              self.port.write("*LANG?")
              self.language = self.port.read()  # TSP, SCPI, SCPI2400
              # set language with *LANG SCPI, *LANG TSP, *LANG SCPI2400 and reboot, ask for language *LANG?
          
              if self.language == "SCPI":
                  self.language = "SCPI2400"
          
          def initialize(self) -> None:
              """Initialize the device. This function is called only once at the start of the measurement."""

Please note that other software that interfaces with the Keithley 2450 might no longer work or must be configured for TSP language as well.

Thanks for adding your problem to the forum! Let us know if it works.

Best, Axel

Natan · March 24, 2026, 2:22pm

Hi, Axel.

It works. I have changed the command set to TSP!

Thank you very much.