I am trying to program the Keithley2400 in python using the pyvisa library via a usb-to-serial rs232 cable. My measurement is a IV sweep of a diode done every 10min for a total of 5days. So what I am trying to do is perform a IV sweep, source current and sense voltage in a 4-wire config, store the measured sweep data in the Keithley2400 buffer and read the buffer once it is finished measuring on to my laptop and store it with a timestamp. I could program a part of this but I am stuck and cannot complete the entire code and I have the following issues and questions:
1] The python code is attached (ki2400_IVsweep.py). After the "Ki2400.read()" statement, I get an error as
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"VisaIOError: VI_ERROR_ASRL_OVERRUN (-1073807252): An overrun error occurred during transfer. A character was not read from the hardware before the next character arrived."
2] I want to sweep the measurements from reverse bias to forward bias, therefore source negative current to positive current and hence sensing negative voltage to positive voltage respectively. How do I do that?
3] How do I add a software trigger so that when the measurement of one sweep is done, the ":FETCh?" command is written and then the Ki2400.read() statement is executed?