Other topics about Controlling Peripherals
The E5071C macro function (E5071C VBA) can be used not only to automate measurements but also to control external measurement instruments connected via USB/GPIB interface by acting as a self-contained system controller (see An Overview of a Control System Based on the Macro Function).
The E5071C macro function (E5071C VBA) performs communications via the COM interface when controlling the E5071C itself, but it communicates via VISA (Virtual Instrument Software Architecture) when controlling external measurement instruments.