Ge Ze

Yes, I saw this thread.. My own Keithley 2400, 2700 devices do not make this error. (same logical code, sequence) Also, I work with RS232. In the event of an error in the code, the error would occur at startup in every cycle. This error sometimes occurs after 30 measurements, then after 500 measurements, and then at the 502nd measurement. Of course I used the NI trace software :-) -113 :-)

Random measurement drop err. -113 Undefined Header - Tektronix and Keithley  forum link... 

The measurement runs fine in labview. It measures fine. Then random Beep and measures "0". It prints an error. The keithley is 2000, but I have seen several threads on the old forum about this error. Was there a solution? THY