I had a problem of communicating with keithley. I have two python codes to control keithley via two gpib cables connected to my computer, they both work well when they work along. But when I tried to run them using single computer to control two keithley, there are problems like the code stuck forever or timeout. Since two gpib cables have two different ports, so I tried to add command “IDN?” to let two keithley identify themselves, but problem is still there. Do you have any suggestion? Thanks!