I need to get the return of the API command below.
Which probe should I use?
If the response shows "-" it mean analog video is present. If it shows "ON", Then The analog video is present.
I'm not sure if you are referring to which assertion when you mentioned probe here. If you are using Gateway, you can use the context variable:
Returns the body of the main/root MIME part, including any attachments; turns the message into a String.
Retrieving data ...