The new 'Message View' in the 1480A application (download here) allows you to see the lowest-level information as it flows on the USB. In addition to USB data packets (shown as 'Data' in the 'Item' column in the 'Message View') there are also 'Event' and 'RxCmd' items available.

Events are inserted in the data stream by the 1480A hardware before sent to the PC. It marks certain important bus events such as Device Connection and/or Device Disconnection. There are also private events in the data stream that are used internally by the 1480A hardware. These are identified via a blank 'Decoded Information' column and can be ignored.

RxCmds are inserted by the NXP USB Transceiver that the 1480A unit uses to snoop on the USB. These RxCmds contain low-level bus information such as On-the-go power events, line state changes, device connection etc. The 'Decoded Information' column in the Message View decodes the information in the RxCmds received from the NXP transceiver.

For a detailed description of the meaning of the RxCmds please see the data sheet from NXP.