USB HID to Serial Interface with ready configured DB25 pin female (for PC com2) and DB9 pin female (for PC com1) adapters. N.B. operates at a fixed 9600 baud 8-bit, no parity and requires serial device to have hardware flow control to avoid overflow / data loss.
The HID (Human Interface Device) interface takes advantage of inbuilt drivers in Windows (98 SE onwards) and Mac OS (9 and X onwards) where the data received at the serial interface is passed to the current application as if it had been entered at the keyboard.