Dual-Port Power Serial

HP 638947-001 is an optional two-port powered serial expansion card for adding serial connectivity to compatible HP retail systems.

It provides two additional powered serial ports. On the HP RP3, the service manual identifies the added connections as COM 3 and COM 4, which can extend the system's serial port capacity for supported peripherals. HP lists the card among the RP3 expansion cards and also includes it in the parts documentation for the rp5800 Retail System.

This is a specific expansion card, rather than a standalone serial cable or a general-purpose adapter. The confirmed model references are HP RP3 and HP rp5800 Retail System.