The USB500 AG can also be used as a USB generator.
In host mode, it provides the VBUS
supply, applies bus states, and sends packets
and waits for responses, but all under control
of your script.
In device mode, it emulates plug-in, waits
for the appropriate bus states and packets,
and responds with the required data, all exactly
as you specify.
To see the detailed interactions on the bus,
use any USB analyser.
The advantage of using a Packet-Master unit
for the analyser is that the powerful GraphicUSB
application is able to control both the analyser
and the generator simultaneously.