Can I control the TTR500A Programmatically? 

Can I control the TTR500A Programmatically? 

Yes, the TTR500A can be controlled Programmatically.

Here is a link to the Programmers manual which contains all the SCPI commands: https://www.tek.com/vna/ttr500-manual-5

In order to communicate with the TTR500A VectorVu-PC software needs to be running and connected to the unit. The address to communicate with the TTR500A will be a GPIB8 address which is a virtual GPIB address. This communicates to the VectorVu-PC software which communicates to the TTR500A unit.