Add an RS232 serial port with circuit isolation to your laptop or desktop computer through USB 1 Port FTDI USB to Serial RS232 Adapter Cable with Isolation USB to RS232 Serial Adapter Cable USB to Serial Cable USB to Serial RS232 Cable USB to DB9 USB to Serial Adapter with Optical Isolation FTDI Adapter FTDI USB UART Serial Adapter Circuit isolation provides protection for sensitive and expensive industrial equipment Portable USB-Powered design requires no bulky power adapter