Javier Navarro Montilla

Hi Jake,

An update on the issue: I have noticed that the Query(SYST:COMM:SER:ENT?) function only reads 16 values from the 2182A buffer. Hence by repeating Query(SYST:COMM:SER:ENT?) several times I can retrieve all the data from 2182A buffer. I have updated my code (see attached) to repeat as many times as required the function  Query(SYST:COMM:SER:ENT?) until the 2182A buffer is empty. It seems to work quite nicely for a sweep with maximum 100 points. When I try with 150 points or more, I always find a -363 error message in 6221, which consists of an input buffer overrun. As I mentioned previously, I know the capacity of 2182A buffer is up to 1024, and I set up the buffer to have the same dimension as the number of points that I want to measure. Where does this buffer overrun comes from?

P/S: I have tried to set the flow control to 'XON' as from my understanding this should prevent any overrun in the input buffer of 6221, however the error -363 doesn't disappear.

Hi Jake,

Thank you very much for your answer. That is exactly what I suspected, that in order to do a query from 2182A I needed to send the query to 2182A and then read the output of the RS232 link with the SYST:COMM:SER:ENT? command. However, using this method I cannot implement a sweep with more than 16 points, which is very inconvenient. Basically, using the code that I previously shared, everything works perfectly fine if the number of points for the sweep is smaller than 16. If I increase the number of points to 17, the variable 'voltage_meas' where I store the data read from Query(SYST:COMM:SER:ENT?) (see attached 'voltage_meas_17_points.png') only shows 16 values instead of 17 as we would expect. In addition, the first ('3\n') and last ('+8.21553742E) measured values do not correspond to voltage values. If I further increase the number of points to 25, we observe the same result (see attached 'voltage_meas_25_points.png') with only 16 read values, where the first and the last one do not correspond to voltage values. 

From the 2182A manual I know the maximum number of points that can be stored in 2182A buffer is 1024, hence I don't believe the problem comes from 2182A. The maximum size of the 6221 buffer is 65536 and I have tried to set it up so it corresponds to the number of points of my sweep, hence I neither think the problem comes from 6221 buffer. I suspect that the element limiting the number of data that can be read is the RS232 cable. However, if I use the example software KI622O.exe provided by Keithley, I am capable to perform a sweep with up to 1024 points using exactly the same setup described before (GPIB from 6221 to the PC and RS232 + Tlink between 6221 and 2182A). Therefore, I believe there must be a way to perform the sweep with high number of points using this setup. The reason why I do not use the KI6220.exe software is because I cannot save the measured voltage values, which is critical for my experiment.

I hope you can help me on how to increase the number measured points. Let me know if further information is required.

Thank you very much.
Javier