we cannot help that much with fixing your Labview application, but I recommend to try once SweepMe! together with the Keithley 2450 driver that we provide.
The basic version of SweepMe! and the driver can be used for free, so that you should be able to test whether you can source the voltage and read the current you like as usual or whether you see the same error with another software.
Such an error might hint to the fact that limits and ranges are set in the wrong command order. Here, I would make sure that you do not accidentally set the source limit of the current instead of the voltage, for example.
Also consider to use SweepMe! in general.
SweepMe! drivers are used by all users of our platform. If there is a bug, the solution will be available to all users. This means our drivers become more and more stable and are usually plug&play.
In contrast, programming your own individual software typically means that each person needs to figure out on their own how to send the commands in the correct order.
In addition to what Axel already said, don’t forget that you cannot set the sourcing value and the compliance limit totally independing from each other. There are usually restrictions regarding the ratio of the source value and the measurement range.
Excerpt from the 2450 manual
The source limits (also known as compliance) prevent the instrument from sourcing a voltage or current over a set value.
[…]
This limit can also be restricted by the measurement range. If a specific measurement range is set, the limit must be more than 0.1 % of the measurement range. If not, an event is generated and the limit is automatically changed to an appropriate value for the selected range. If you set the measurement range to be automatically selected, the measurement range does not affect the limit.
If you attempt to change the source limit to a value that is not appropriate for the selected source range, the source limit is not changed and a warning is generated. You must change the source range before you can select the new limit. The lowest allowable limit is based on the load and the source value. For example, if you are sourcing 1 V to a 1 k resistor, the lowest allowable limit is 1 mA (1 V/1 k = 1 mA). Setting a limit lower than 1 mA limits the source.
The reason behind this is that the SMU does current and voltage monitoring only based on voltage monitoring, in the case of current via a shunt resistor. For both values to be monitored simultaneously, they both need to fit in the dynamic range of the ADC at once, hence the limitation.
