Features USB to Straight-Through RS232 Serial Adapter Integrated 2500Vrms Optical Isolation Circuits 500W Bi-Directional Surge Protection Circuits The ICUSB2321FIS 1-Port FTDI USB to Serial RS232 Adapter Cable with Optical Isolation converts an available USB 1.1 or 2.0 port into an RS232 DB9 port that can be used to connect, monitor and control your serial devices. The USB to serial adapter features integrated optical isolation circuits and surge protection to protect your critical, sensitive control equipment against electrical damage, making it a viable solution for costly industrial serial devices.