On both the older 4200-SCS that you have and our 4200A-SCS, there is the KXCI interface.
This is the Keithley eXternal Command Interface or KXCI.
Close KITE or Clarius and invoke KXCI.
But first visit KCON and config the LAN or GPIB interface.
Attached is an application note on using Python with 4200A-SCS.